1
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Plasencia DM, Rodgers LH, Knighton AR, Eckenhoff RG, White ER. Antagonism of propofol anesthesia by alkyl-fluorobenzene derivatives. Sci Rep 2024; 14:15943. [PMID: 38987614 PMCID: PMC11236999 DOI: 10.1038/s41598-024-66672-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Accepted: 07/03/2024] [Indexed: 07/12/2024] Open
Abstract
Despite their frequent use across many clinical settings, general anesthetics are medications with lethal side effects and no reversal agents. A fluorinated analogue of propofol has previously been shown to antagonize propofol anesthesia in tadpoles and zebrafish, but little further investigation of this class of molecules as anesthetic antagonists has been conducted. A 13-member library of alkyl-fluorobenzene derivatives was tested in an established behavioral model of anesthesia in zebrafish at 5 days post fertilization. These compounds were examined for their ability to antagonize propofol and two volatile anesthetics, as well as their interaction with the anesthetic-binding model protein apoferritin. Two compounds provided significant antagonism of propofol, and when combined, were synergistic, suggesting more than one antagonist sensitive target site. These compounds did not antagonize the volatile anesthetics, indicating some selectivity amongst general anesthetics. For the compounds with the most antagonistic potency, similarities in structure and binding to apoferritin may be suggestive of competitive antagonism; however, this was not supported by a Schild analysis. This is consistent with multiple targets contributing to general anesthesia, but whether these are physiologic antagonists or are antagonists at only some subset of the many anesthetic potential targets remains unclear, and will require additional investigation.
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Affiliation(s)
- Diana M Plasencia
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Liam H Rodgers
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Alexys R Knighton
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Roderic G Eckenhoff
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - E Railey White
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA.
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2
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Microtubules as a potential platform for energy transfer in biological systems: a target for implementing individualized, dynamic variability patterns to improve organ function. Mol Cell Biochem 2023; 478:375-392. [PMID: 35829870 DOI: 10.1007/s11010-022-04513-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 06/24/2022] [Indexed: 02/07/2023]
Abstract
Variability characterizes the complexity of biological systems and is essential for their function. Microtubules (MTs) play a role in structural integrity, cell motility, material transport, and force generation during mitosis, and dynamic instability exemplifies the variability in the proper function of MTs. MTs are a platform for energy transfer in cells. The dynamic instability of MTs manifests itself by the coexistence of growth and shortening, or polymerization and depolymerization. It results from a balance between attractive and repulsive forces between tubulin dimers. The paper reviews the current data on MTs and their potential roles as energy-transfer cellular structures and presents how variability can improve the function of biological systems in an individualized manner. The paper presents the option for targeting MTs to trigger dynamic improvement in cell plasticity, regulate energy transfer, and possibly control quantum effects in biological systems. The described system quantifies MT-dependent variability patterns combined with additional personalized signatures to improve organ function in a subject-tailored manner. The platform can regulate the use of MT-targeting drugs to improve the response to chronic therapies. Ongoing trials test the effects of this platform on various disorders.
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3
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Joseph TT, Bu W, Lin W, Zoubak L, Yeliseev A, Liu R, Eckenhoff RG, Brannigan G. Ketamine Metabolite (2 R,6 R)-Hydroxynorketamine Interacts with μ and κ Opioid Receptors. ACS Chem Neurosci 2021; 12:1487-1497. [PMID: 33905229 PMCID: PMC8154314 DOI: 10.1021/acschemneuro.0c00741] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
![]()
Ketamine is an anesthetic,
analgesic, and antidepressant whose
secondary metabolite (2R,6R)-hydroxynorketamine
(HNK) has N-methyl-d-aspartate-receptor-independent
antidepressant activity in a rodent model. In humans, naltrexone attenuates
its antidepressant effect, consistent with opioid pathway involvement.
No detailed biophysical description is available of opioid receptor
binding of ketamine or its metabolites. Using molecular dynamics simulations
with free energy perturbation, we characterize the binding site and
affinities of ketamine and metabolites in μ and κ opioid
receptors, finding a profound effect of the protonation state. G-protein
recruitment assays show that HNK is an inverse agonist, attenuated
by naltrexone, in these receptors with IC50 values congruous
with our simulations. Overall, our findings are consistent with opioid
pathway involvement in ketamine function.
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Affiliation(s)
- Thomas T. Joseph
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Weiming Bu
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Wenzhen Lin
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Department of Biochemistry and Molecular Biology, Guangxi Medical University, Nanning, Guangxi 530021, China
| | - Lioudmila Zoubak
- National Institute of Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20852, United States
| | - Alexei Yeliseev
- National Institute of Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20852, United States
| | - Renyu Liu
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Roderic G. Eckenhoff
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Grace Brannigan
- Center for Computational and Integrative Biology and Department of Physics, Rutgers University, Camden, New Jersey 08102, United States
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4
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White ER, Leace DM, Bedell VM, Bhanu NV, Garcia BA, Dailey WP, Eckenhoff RG. Synthesis and Characterization of a Diazirine-Based Photolabel of the Nonanesthetic Fropofol. ACS Chem Neurosci 2021; 12:176-183. [PMID: 33355437 PMCID: PMC7948515 DOI: 10.1021/acschemneuro.0c00667] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The mechanisms of general anesthetics have been debated in the literature for many years and continue to be of great interest. As anesthetic molecules are notoriously difficult to study due to their low binding affinities and multitude of binding partners, it is advantageous to have additional tools to study these interactions. Fropofol is a hydroxyl to fluorine-substituted propofol analogue that is able to antagonize the actions of propofol. Understanding fropofol's ability to antagonize propofol would facilitate further characterization of the binding interactions of propofol that may contribute to its anesthetic actions. However, the study of fropofol's molecular interactions has many of the same difficulties as its parent compound. Here, we present the synthesis and characterization of ortho-azi-fropofol (AziFo) as a suitable photoaffinity label (PAL) of fropofol that can be used to covalently label proteins of interest to characterize fropofol's binding interactions and their contribution to general anesthetic antagonism.
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Affiliation(s)
- E Railey White
- Perelman School of Medicine, Department of Anesthesiology and Critical Care, University of Pennsylvania, John Morgan Building, 3620 Hamilton Walk, Philadelphia, Pennsylvania 19104, United States
| | - David M Leace
- Perelman School of Medicine, Department of Anesthesiology and Critical Care, University of Pennsylvania, John Morgan Building, 3620 Hamilton Walk, Philadelphia, Pennsylvania 19104, United States
| | - Victoria M Bedell
- Perelman School of Medicine, Department of Anesthesiology and Critical Care, University of Pennsylvania, John Morgan Building, 3620 Hamilton Walk, Philadelphia, Pennsylvania 19104, United States
| | - Natarajan V Bhanu
- Perelman School of Medicine, Department of Biochemistry and Biophysics, Smilow Center for Translational Research, University of Pennsylvania, 3400 Civic Center Boulevard, Philadelphia, Pennsylvania 19104, United States
| | - Benjamin A Garcia
- Perelman School of Medicine, Department of Biochemistry and Biophysics, Smilow Center for Translational Research, University of Pennsylvania, 3400 Civic Center Boulevard, Philadelphia, Pennsylvania 19104, United States
| | - William P Dailey
- Department of Chemistry, University of Pennsylvania, 231 S. 34th Street, Philadelphia, Pennsylvania 19104, United States
| | - Roderic G Eckenhoff
- Perelman School of Medicine, Department of Anesthesiology and Critical Care, University of Pennsylvania, John Morgan Building, 3620 Hamilton Walk, Philadelphia, Pennsylvania 19104, United States
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5
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Bi D, Yang J, Hong JY, Parikh P, Hinds N, Infanti J, Lin H, Weiser BP. Substrate-Dependent Modulation of SIRT2 by a Fluorescent Probe, 1-Aminoanthracene. Biochemistry 2020; 59:3869-3878. [PMID: 32941003 PMCID: PMC7880049 DOI: 10.1021/acs.biochem.0c00564] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Sirtuin isoform 2 (SIRT2) is an enzyme that catalyzes the removal of acyl groups from lysine residues. SIRT2's catalytic domain has a hydrophobic tunnel where its substrate acyl groups bind. Here, we report that the fluorescent probe 1-aminoanthracene (AMA) binds within SIRT2's hydrophobic tunnel in a substrate-dependent manner. AMA's interaction with SIRT2 was characterized by its enhanced fluorescence upon protein binding (>10-fold). AMA interacted weakly with SIRT2 alone in solution (Kd = 37 μM). However, when SIRT2 was equilibrated with a decanoylated peptide substrate, AMA's affinity for SIRT2 was enhanced ∼10-fold (Kd = 4 μM). The peptide's decanoyl chain and AMA co-occupied SIRT2's hydrophobic tunnel when bound to the protein. In contrast, binding of AMA to SIRT2 was competitive with a myristoylated substrate whose longer acyl chain occluded the entire tunnel. AMA competitively inhibited SIRT2 demyristoylase activity with an IC50 of 21 μM, which was significantly more potent than its inhibition of other deacylase activities. Finally, binding and structural analysis suggests that the AMA binding site in SIRT2's hydrophobic tunnel was structurally stabilized when SIRT2 interacted with a decanoylated or 4-oxononanoylated substrate, but AMA's binding site was less stable when SIRT2 was bound to an acetylated substrate. Our use of AMA to explore changes in SIRT2's hydrophobic tunnel that are induced by interactions with specific acylated substrates has implications for developing ligands that modulate SIRT2's substrate specificity.
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Affiliation(s)
- David Bi
- Department of Molecular Biology, Rowan University School of Osteopathic Medicine, Stratford, New Jersey 08084, United States
| | - Jie Yang
- Department of Molecular Biology, Rowan University School of Osteopathic Medicine, Stratford, New Jersey 08084, United States
| | - Jun Young Hong
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Prashit Parikh
- Department of Molecular Biology, Rowan University School of Osteopathic Medicine, Stratford, New Jersey 08084, United States
| | - Nicole Hinds
- Department of Molecular Biology, Rowan University School of Osteopathic Medicine, Stratford, New Jersey 08084, United States
| | - Joseph Infanti
- Department of Molecular Biology, Rowan University School of Osteopathic Medicine, Stratford, New Jersey 08084, United States
| | - Hening Lin
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States.,Howard Hughes Medical Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Brian P Weiser
- Department of Molecular Biology, Rowan University School of Osteopathic Medicine, Stratford, New Jersey 08084, United States
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6
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Lv Y, Dai W, Ge A, Fan Y, Hu G, Zeng Y. Aquaporin-4 knockout mice exhibit increased hypnotic susceptibility to ketamine. Brain Behav 2018; 8:e00990. [PMID: 29745050 PMCID: PMC5991570 DOI: 10.1002/brb3.990] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 02/07/2018] [Accepted: 03/11/2018] [Indexed: 11/06/2022] Open
Abstract
PURPOSE This study examines anesthetic/hypnotic effects of ketamine in AQP4 knockout (KO) and wild-type (WT) mice with the particular focus on neurotransmission. MATERIALS AND METHODS Ketamine (100 mg/kg) was intraperitoneally injected in 16 WT and 16 KO mice. The hypnotic potencies were evaluated by the loss of the righting reflex (LORR). The amino acids neurotransmitter levels in prefrontal cortex were measured by microdialysis. RESULTS This study demonstrated that AQP4 knockout significantly shortened the latency compared with WT mice (98.0 ± 4.2 vs. 138.1 ± 15.0 s, p < .05) and prolonged duration of LORR (884.7 ± 58.6 vs. 562.0 ± 51.7 s, p < .05) compared with WT mice in LORR induced by ketamine. Microdialysis showed that lack of AQP4 markedly decreased glutamate level within 20 min (p < .05) and increased γ-aminobutyric acid (GABA) level within 30-40 min (p < .05) after use of ketamine. Moreover, the levels of taurine were remarkably higher in KO mice than in WT mice, but no obvious differences in aspartate were observed between two genotypes. CONCLUSION AQP4 deficiency led to more susceptibility of mice to ketamine, which is probably due to the modulation of specific neurotransmitters, hinting an essential maintenance of synaptic activity mediated by AQP4 in the action of ketamine.
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Affiliation(s)
- Yunluo Lv
- Department of Anesthesiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Wangshu Dai
- The Comprehensive Cancer Centre of Drum Tower Hospital, Medical School of Nanjing University, Clinical Cancer Institute of Nanjing University, Nanjing, China
| | - Ai Ge
- Department of Respiratory Medicine, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yi Fan
- Jiangsu Key Laboratory of Neurodegeneration, Department of Pharmacology, Nanjing Medical University, Nanjing, China
| | - Gang Hu
- Jiangsu Key Laboratory of Neurodegeneration, Department of Pharmacology, Nanjing Medical University, Nanjing, China
| | - Yinming Zeng
- Jiangsu Province Institute of Anesthesiology, Xuzhou Medical University, Xuzhou, China
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7
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Fluorescent Anesthetics. Methods Enzymol 2018; 603:93-101. [PMID: 29673536 DOI: 10.1016/bs.mie.2018.02.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Methods for using exogenous fluorophore and general anesthetic 1-aminoanthracene (1-AMA) and its photoactive derivative 1-azidoanthracene (1-AZA) are provided. 1-AMA potentiates GABAA chloride currents and immobilizes Xenopus laevis tadpoles. Cellular and tissue anesthetic distribution can be imaged for quantifying "on-pathway" and "off-pathway" targets. 1-AZA shares targets with 1-AMA and offers further optoanesthetic spatial and temporal control upon near-UV laser irradiation. Furthermore, 1-AZA adduction provides screening of possible relevant anesthetic protein targets and binding site characterization. We highlight several useful imaging and binding assays to demonstrate utility of 1-AMA and its derivative 1-AZA.
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8
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Abstract
Anesthetics interact with a broad range of different targets, including both soluble and membrane-bound proteins. Understanding these interactions at the molecular level requires detailed structural knowledge of anesthetic-protein complexes, and one of the most productive routes to such knowledge is X-ray crystallography. In this chapter we discuss the application of this technique to the analysis of complexes of anesthetics with soluble proteins. The model protein apoferritin is highlighted, and protocols are presented for obtaining diffraction-quality crystals of this protein in complex with different general anesthetics.
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9
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Craddock TJA, Kurian P, Preto J, Sahu K, Hameroff SR, Klobukowski M, Tuszynski JA. Anesthetic Alterations of Collective Terahertz Oscillations in Tubulin Correlate with Clinical Potency: Implications for Anesthetic Action and Post-Operative Cognitive Dysfunction. Sci Rep 2017; 7:9877. [PMID: 28852014 PMCID: PMC5575257 DOI: 10.1038/s41598-017-09992-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 08/01/2017] [Indexed: 12/29/2022] Open
Abstract
Anesthesia blocks consciousness and memory while sparing non-conscious brain activities. While the exact mechanisms of anesthetic action are unknown, the Meyer-Overton correlation provides a link between anesthetic potency and solubility in a lipid-like, non-polar medium. Anesthetic action is also related to an anesthetic's hydrophobicity, permanent dipole, and polarizability, and is accepted to occur in lipid-like, non-polar regions within brain proteins. Generally the protein target for anesthetics is assumed to be neuronal membrane receptors and ion channels, however new evidence points to critical effects on intra-neuronal microtubules, a target of interest due to their potential role in post-operative cognitive dysfunction (POCD). Here we use binding site predictions on tubulin, the protein subunit of microtubules, with molecular docking simulations, quantum chemistry calculations, and theoretical modeling of collective dipole interactions in tubulin to investigate the effect of a group of gases including anesthetics, non-anesthetics, and anesthetic/convulsants on tubulin dynamics. We found that these gases alter collective terahertz dipole oscillations in a manner that is correlated with their anesthetic potency. Understanding anesthetic action may help reveal brain mechanisms underlying consciousness, and minimize POCD in the choice and development of anesthetics used during surgeries for patients suffering from neurodegenerative conditions with compromised cytoskeletal microtubules.
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Affiliation(s)
- Travis J A Craddock
- Departments of Psychology & Neuroscience, Computer Science, and Clinical Immunology, and the Clinical Systems Biology Group, Institute for Neuro-Immune Medicine, Nova Southeastern University, Fort Lauderdale, Florida, USA.
| | - Philip Kurian
- National Human Genome Center and Department of Medicine, Howard University College of Medicine, and Computational Physics Laboratory, Howard University, Washington, DC, USA
| | - Jordane Preto
- Department of Experimental Oncology, Cross Cancer Institute, Edmonton, Alberta, Canada
| | - Kamlesh Sahu
- Department of Physics, University of Alberta, Edmonton, Alberta, Canada
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Canada
| | - Stuart R Hameroff
- Departments of Anesthesiology and Psychology, Center for Consciousness Studies, The University of Arizona Health Sciences Center, Tucson, Arizona, USA
| | | | - Jack A Tuszynski
- Department of Experimental Oncology, Cross Cancer Institute, Edmonton, Alberta, Canada
- Department of Physics, University of Alberta, Edmonton, Alberta, Canada
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10
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Qiu L, Lin J, Liu Q, Wang S, Lv G, Li K, Shi H, Huang Z, Bertaccini EJ. The Role of the Hydroxyl Group in Propofol-Protein Target Recognition: Insights from ONIOM Studies. J Phys Chem B 2017; 121:5883-5896. [PMID: 28548837 DOI: 10.1021/acs.jpcb.7b02079] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Propofol (PFL, 1-hydroxyl-2,6-diisopropylbenzene) is currently used widely as one of the most well-known intravenous anesthetics to relieve surgical suffering, but its mechanism of action is not yet clear. Previous experimental studies have demonstrated that the hydroxyl group of PFL plays a dominant role in the molecular recognition of PFL with receptors that lead to hypnosis. To further explore the mechanism of anesthesia induced by PFL in the present work, the exact binding features and interaction details of PFL with three important proteins, human serum albumin (HSA), the pH-gated ion channel from Gloeobacter violaceus (GLIC), and horse spleen apoferritin (HSAF), were investigated systematically by using a rigorous three-layer ONIOM (M06-2X/6-31+G*:PM6:AMBER) method. Additionally, to further characterize the possible importance of such hydroxyl interactions, a similar set of calculations was carried out on the anesthetically inactive fropofol (FFL, 1-fluoro-2,6-diisopropylbenzene) in which the fluorine was substituted for the hydroxyl. According to the ONIOM calculations, atoms in molecules (AIM) analyses, and electrostatic potential (ESP) analyses, the significance of hydrogen bond, halogen bond, and hydrophobic interactions in promoting proper molecular recognition was revealed. The binding interaction energies of PFL with different proteins were generally larger than FFL and are a significant determinant of their differential anesthetic efficacies. Interestingly, although the hydrogen-bonding effect of the hydroxyl moiety was prominent in propofol, the substitution of the 1-hydroxyl by a fluorine atom did not prevent FFL from binding to the protein via a halogen-bonding interaction. It therefore became clear that multiple specific interactions rather than just hydrogen or halogen bonds must be taken into account to explain the different anesthesia endpoints caused by PFL and FFL. The contributions of key residues in ligand-receptor binding were also quantified, and the calculated results agreed with many available experimental observations. This work will provide complementary insights into the molecular mechanisms of anesthetic action for PFL from a robust theoretical point of view. This will not only assist in interpreting experimental observations but will also help to develop working hypotheses for further experiments and future drug design.
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Affiliation(s)
- Ling Qiu
- Key Laboratory of Nuclear Medicine, Ministry of Health, & Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine , Wuxi 214063, P. R. China.,Department of Anesthesia, Stanford University School of Medicine , 300 Pasteur Drive, Stanford, California 94305, United States
| | - Jianguo Lin
- Key Laboratory of Nuclear Medicine, Ministry of Health, & Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine , Wuxi 214063, P. R. China
| | - Qingzhu Liu
- Key Laboratory of Nuclear Medicine, Ministry of Health, & Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine , Wuxi 214063, P. R. China
| | - Shanshan Wang
- Key Laboratory of Nuclear Medicine, Ministry of Health, & Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine , Wuxi 214063, P. R. China
| | - Gaochao Lv
- Key Laboratory of Nuclear Medicine, Ministry of Health, & Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine , Wuxi 214063, P. R. China
| | - Ke Li
- Key Laboratory of Nuclear Medicine, Ministry of Health, & Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine , Wuxi 214063, P. R. China
| | - Haiming Shi
- Key Laboratory of Nuclear Medicine, Ministry of Health, & Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine , Wuxi 214063, P. R. China
| | - Zhengkun Huang
- Key Laboratory of Nuclear Medicine, Ministry of Health, & Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine , Wuxi 214063, P. R. China
| | - Edward J Bertaccini
- Department of Anesthesia, Stanford University School of Medicine , 300 Pasteur Drive, Stanford, California 94305, United States.,Palo Alto VA Health Care System, 112A, PAVAHCS , 3801 Miranda Avenue, Palo Alto, California 94304, United States
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11
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Woll KA, Peng W, Liang Q, Zhi L, Jacobs JA, Maciunas L, Bhanu N, Garcia BA, Covarrubias M, Loll PJ, Dailey WP, Eckenhoff RG. Photoaffinity Ligand for the Inhalational Anesthetic Sevoflurane Allows Mechanistic Insight into Potassium Channel Modulation. ACS Chem Biol 2017; 12:1353-1362. [PMID: 28333442 DOI: 10.1021/acschembio.7b00222] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Sevoflurane is a commonly used inhaled general anesthetic. Despite this, its mechanism of action remains largely elusive. Compared to other anesthetics, sevoflurane exhibits distinct functional activity. In particular, sevoflurane is a positive modulator of voltage-gated Shaker-related potassium channels (Kv1.x), which are key regulators of action potentials. Here, we report the synthesis and validation of azisevoflurane, a photoaffinity ligand for the direct identification of sevoflurane binding sites in the Kv1.2 channel. Azisevoflurane retains major sevoflurane protein binding interactions and pharmacological properties within in vivo models. Photoactivation of azisevoflurane induces adduction to amino acid residues that accurately reported sevoflurane protein binding sites in model proteins. Pharmacologically relevant concentrations of azisevoflurane analogously potentiated wild-type Kv1.2 and the established mutant Kv1.2 G329T. In wild-type Kv1.2 channels, azisevoflurane photolabeled Leu317 within the internal S4-S5 linker, a vital helix that couples the voltage sensor to the pore region. A residue lining the same binding cavity was photolabeled by azisevoflurane and protected by sevoflurane in the Kv1.2 G329T. Mutagenesis of Leu317 in WT Kv1.2 abolished sevoflurane voltage-dependent positive modulation. Azisevoflurane additionally photolabeled a second distinct site at Thr384 near the external selectivity filter in the Kv1.2 G329T mutant. The identified sevoflurane binding sites are located in critical regions involved in gating of Kv channels and related ion channels. Azisevoflurane has thus emerged as a new tool to discover inhaled anesthetic targets and binding sites and investigate contributions of these targets to general anesthesia.
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Affiliation(s)
- Kellie A. Woll
- Department of Anesthesiology & Critical Care, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, Philadelphia, Pennsylvania 19104, United States
- Department
of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, Philadelphia, Pennsylvania 19104, United States
| | - Wesley Peng
- Department
of Chemistry, University of Pennsylvania School of Arts and Sciences, 231 S. 34th Street, Philadelphia, Pennsylvania 19104, United States
| | - Qiansheng Liang
- Department of Neuroscience and Vickie and
Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College, Thomas Jefferson University, 900 Walnut Street, JHN 417, Philadelphia, Pennsylvania 19107, United States
| | - Lianteng Zhi
- Department of Neuroscience and Vickie and
Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College, Thomas Jefferson University, 900 Walnut Street, JHN 417, Philadelphia, Pennsylvania 19107, United States
| | - Jack A. Jacobs
- Department
of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, Philadelphia, Pennsylvania 19104, United States
| | - Lina Maciunas
- Department
of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129, United States
| | - Natarajan Bhanu
- Epigenetics Program,
Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, 3400 Civic Center, Building 421, Philadelphia, Pennsylvania 19104, United States
| | - Benjamin A. Garcia
- Epigenetics Program,
Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, 3400 Civic Center, Building 421, Philadelphia, Pennsylvania 19104, United States
| | - Manuel Covarrubias
- Department of Neuroscience and Vickie and
Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College, Thomas Jefferson University, 900 Walnut Street, JHN 417, Philadelphia, Pennsylvania 19107, United States
| | - Patrick J. Loll
- Department
of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129, United States
| | - William P. Dailey
- Department
of Chemistry, University of Pennsylvania School of Arts and Sciences, 231 S. 34th Street, Philadelphia, Pennsylvania 19104, United States
| | - Roderic G. Eckenhoff
- Department of Anesthesiology & Critical Care, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, Philadelphia, Pennsylvania 19104, United States
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12
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Guo J, Xu N, Yao Y, Lin J, Li R, Li JW. Efficient expression of recombinant human heavy chain ferritin (FTH1) with modified peptides. Protein Expr Purif 2017; 131:101-108. [DOI: 10.1016/j.pep.2016.06.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Revised: 05/27/2016] [Accepted: 06/13/2016] [Indexed: 11/26/2022]
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13
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Woll KA, Murlidaran S, Pinch BJ, Hénin J, Wang X, Salari R, Covarrubias M, Dailey WP, Brannigan G, Garcia BA, Eckenhoff RG. A Novel Bifunctional Alkylphenol Anesthetic Allows Characterization of γ-Aminobutyric Acid, Type A (GABAA), Receptor Subunit Binding Selectivity in Synaptosomes. J Biol Chem 2016; 291:20473-86. [PMID: 27462076 PMCID: PMC5034043 DOI: 10.1074/jbc.m116.736975] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 07/25/2016] [Indexed: 12/19/2022] Open
Abstract
Propofol, an intravenous anesthetic, is a positive modulator of the GABAA receptor, but the mechanistic details, including the relevant binding sites and alternative targets, remain disputed. Here we undertook an in-depth study of alkylphenol-based anesthetic binding to synaptic membranes. We designed, synthesized, and characterized a chemically active alkylphenol anesthetic (2-((prop-2-yn-1-yloxy)methyl)-5-(3-(trifluoromethyl)-3H-diazirin-3-yl)phenol, AziPm-click (1)), for affinity-based protein profiling (ABPP) of propofol-binding proteins in their native state within mouse synaptosomes. The ABPP strategy captured ∼4% of the synaptosomal proteome, including the unbiased capture of five α or β GABAA receptor subunits. Lack of γ2 subunit capture was not due to low abundance. Consistent with this, independent molecular dynamics simulations with alchemical free energy perturbation calculations predicted selective propofol binding to interfacial sites, with higher affinities for α/β than γ-containing interfaces. The simulations indicated hydrogen bonding is a key component leading to propofol-selective binding within GABAA receptor subunit interfaces, with stable hydrogen bonds observed between propofol and α/β cavity residues but not γ cavity residues. We confirmed this by introducing a hydrogen bond-null propofol analogue as a protecting ligand for targeted-ABPP and observed a lack of GABAA receptor subunit protection. This investigation demonstrates striking interfacial GABAA receptor subunit selectivity in the native milieu, suggesting that asymmetric occupancy of heteropentameric ion channels by alkylphenol-based anesthetics is sufficient to induce modulation of activity.
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Affiliation(s)
- Kellie A Woll
- From the Departments of Anesthesiology and Critical Care and Pharmacology and
| | | | - Benika J Pinch
- the Department of Chemistry, University of Pennsylvania School of Arts and Sciences, Philadelphia, Pennsylvania 19104
| | - Jérôme Hénin
- the Laboratoire de Biochimie Théorique, Institut de Biologie Physico-Chimique, CNRS UMR 8251 and Université Paris Diderot, 5013 Paris, France, and
| | - Xiaoshi Wang
- the Epigenetics Program, Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104
| | - Reza Salari
- the Center for Computational and Integrative Biology and Department of Physics, Rutgers University, Camden, New Jersey 08102
| | - Manuel Covarrubias
- the Department of Neuroscience and Farber Institute for Neuroscience, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
| | - William P Dailey
- the Department of Chemistry, University of Pennsylvania School of Arts and Sciences, Philadelphia, Pennsylvania 19104
| | - Grace Brannigan
- the Center for Computational and Integrative Biology and Department of Physics, Rutgers University, Camden, New Jersey 08102
| | - Benjamin A Garcia
- the Epigenetics Program, Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104
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Affiliation(s)
| | - Ivan J. Dmochowski
- Department of Chemistry University of Pennsylvania 231 S. 34thSt. Philadelphia PA 19104
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15
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Woll KA, Weiser BP, Liang Q, Meng T, McKinstry-Wu A, Pinch B, Dailey WP, Gao WD, Covarrubias M, Eckenhoff RG. Role for the propofol hydroxyl in anesthetic protein target molecular recognition. ACS Chem Neurosci 2015; 6:927-35. [PMID: 25799399 DOI: 10.1021/acschemneuro.5b00078] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Propofol is a widely used intravenous general anesthetic. We synthesized 2-fluoro-1,3-diisopropylbenzene, a compound that we call "fropofol", to directly assess the significance of the propofol 1-hydroxyl for pharmacologically relevant molecular recognition in vitro and for anesthetic efficacy in vivo. Compared to propofol, fropofol had a similar molecular volume and only a small increase in hydrophobicity. Isothermal titration calorimetry and competition assays revealed that fropofol had higher affinity for a protein site governed largely by van der Waals interactions. Within another protein model containing hydrogen bond interactions, propofol demonstrated higher affinity. In vivo, fropofol demonstrated no anesthetic efficacy, but at high concentrations produced excitatory activity in tadpoles and mice; fropofol also antagonized propofol-induced hypnosis. In a propofol protein target that contributes to hypnosis, α1β2γ2L GABAA receptors, fropofol demonstrated no significant effect alone or on propofol positive allosteric modulation of the ion channel, suggesting an additional requirement for the 1-hydroxyl within synaptic GABAA receptor site(s). However, fropofol caused similar adverse cardiovascular effects as propofol by a dose-dependent depression of myocardial contractility. Our results directly implicate the propofol 1-hydroxyl as contributing to molecular recognition within protein targets leading to hypnosis, but not necessarily within protein targets leading to side effects of the drug.
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Affiliation(s)
| | | | - Qiansheng Liang
- Department
of Neuroscience, Sidney Kimmel Medical College, Thomas Jefferson University, 900 Walnut Street, JHN 417, Philadelphia, Pennsylvania 19107, United States
| | - Tao Meng
- Department of Anesthesiology, Qilu Hospital, Shandong University, 107 Wenhua Xi Road, Jinan, 250012 P. R. China
- Department of Anesthesiology
and Critical Care Medicine, Johns Hopkins University School of Medicine, 600 N. Wolfe Street, Baltimore, Maryland 21287, United States
| | | | - Benika Pinch
- Department of Chemistry, University of Pennsylvania School of Arts and Sciences, 231 S. 34th Street, Philadelphia, Pennsylvania 19104, United States
| | - William P. Dailey
- Department of Chemistry, University of Pennsylvania School of Arts and Sciences, 231 S. 34th Street, Philadelphia, Pennsylvania 19104, United States
| | - Wei Dong Gao
- Department of Anesthesiology
and Critical Care Medicine, Johns Hopkins University School of Medicine, 600 N. Wolfe Street, Baltimore, Maryland 21287, United States
| | - Manuel Covarrubias
- Department
of Neuroscience, Sidney Kimmel Medical College, Thomas Jefferson University, 900 Walnut Street, JHN 417, Philadelphia, Pennsylvania 19107, United States
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Lochner M, Thompson AJ. A review of fluorescent ligands for studying 5-HT3 receptors. Neuropharmacology 2015; 98:31-40. [PMID: 25892507 DOI: 10.1016/j.neuropharm.2015.04.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Revised: 04/01/2015] [Accepted: 04/07/2015] [Indexed: 12/19/2022]
Abstract
The use of fluorescence is a valuable and increasingly accessible means of probing the pharmacology and physiology of cells and their receptors. To date, the use of fluorescence-based methods for 5-HT3 receptor research has been quite limited and, although a variety of approaches have been described, these are broadly distributed throughout the literature. In this review we condense these findings into a single, accessible source of reference with the hope of promoting the use of these valuable molecular probes. This article is part of the Special Issue entitled 'Fluorescent Tools in Neuropharmacology'.
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Affiliation(s)
- Martin Lochner
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012, Bern, Switzerland.
| | - Andrew J Thompson
- Department of Pharmacology, Tennis Court Road, Cambridge, CB2 1PD, UK.
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Abstract
BACKGROUND The development of novel anesthetics has historically been a process of combined serendipity and empiricism, with most recent new anesthetics developed via modification of existing anesthetic structures. METHODS Using a novel high-throughput screen employing the fluorescent anesthetic 1-aminoanthracene and apoferritin as a surrogate for on-pathway anesthetic protein target(s), we screened a 350,000 compound library for competition with 1-aminoanthracene-apoferritin binding. Hit compounds meeting structural criteria had their binding affinities for apoferritin quantified with isothermal titration calorimetry and were tested for γ-aminobutyric acid type A receptor binding using a flunitrazepam binding assay. Chemotypes with a strong presence in the top 700 and exhibiting activity via isothermal titration calorimetry were selected for medicinal chemistry optimization including testing for anesthetic potency and toxicity in an in vivo Xenopus laevis tadpole assay. Compounds with low toxicity and high potency were tested for anesthetic potency in mice. RESULTS From an initial chemical library of more than 350,000 compounds, we identified 2,600 compounds that potently inhibited 1-aminoanthracene binding to apoferritin. A subset of compounds chosen by structural criteria (700) was successfully reconfirmed using the initial assay. Based on a strong presence in both the initial and secondary screens the 6-phenylpyridazin-3(2H)-one chemotype was assessed for anesthetic activity in tadpoles. Medicinal chemistry efforts identified four compounds with high potency and low toxicity in tadpoles, two were found to be effective novel anesthetics in mice. CONCLUSION The authors demonstrate the first use of a high-throughput screen to successfully identify a novel anesthetic chemotype and show mammalian anesthetic activity for members of that chemotype.
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Pagano T, Carcamo N, Kenny JE. Investigation of the fluorescence quenching of 1-aminoanthracene by dissolved oxygen in cyclohexane. J Phys Chem A 2014; 118:11512-20. [PMID: 25427103 DOI: 10.1021/jp5094806] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
This study provides a detailed investigation of the fluorescence quenching mechanisms of the fluorophore, 1-aminoanthracene, by dissolved oxygen in cyclohexane. Dynamic/collisional quenching dominates in the system studied, but there is also a small component of static quenching. Stern-Volmer plots revealed that the dynamic quenching constant is 0.445 ± 0.014 mM(-1) and represents ∼95% of total quenching in the system. The static quenching rate constant is 0.024 ± 0.001 mM(-1), and mechanisms by complex formation and "sphere of action" static quenching were examined. Compensation of steady-state fluorescence data for solvent loss during the gradual deoxygenation period of the experiment was found to be important in order to conduct a thorough evaluation of the different quenching mechanisms of the system. The enhancement factors, (F(o)/F) and (τ(o)/τ), for 1-aminoanthracene were determined to be 2.20 ± 0.01 and 2.08 ± 0.01, respectively, and the diffusion-controlled bimolecular rate constant was found to be 2.1 × 10(10) ± 0.2 × 10(10) M(-1) s(-1). The work involved the development of a novel instrumental setup that simultaneously measures several important spectroscopic parameters (steady-state fluorescence intensity, absorbance, fluorescence lifetime, and dissolved oxygen concentration) for the careful study of oxygen quenching mechanisms of 1-aminoanthracene in a cyclohexane solution.
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Affiliation(s)
- Todd Pagano
- Department of Science & Mathematics/Laboratory Science Technology program, Rochester Institute of Technology/National Technical Institute for the Deaf , Rochester, New York 14623, United States
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H-ferritin-nanocaged doxorubicin nanoparticles specifically target and kill tumors with a single-dose injection. Proc Natl Acad Sci U S A 2014; 111:14900-5. [PMID: 25267615 DOI: 10.1073/pnas.1407808111] [Citation(s) in RCA: 350] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
An ideal nanocarrier for efficient drug delivery must be able to target specific cells and carry high doses of therapeutic drugs and should also exhibit optimized physicochemical properties and biocompatibility. However, it is a tremendous challenge to engineer all of the above characteristics into a single carrier particle. Here, we show that natural H-ferritin (HFn) nanocages can carry high doses of doxorubicin (Dox) for tumor-specific targeting and killing without any targeting ligand functionalization or property modulation. Dox-loaded HFn (HFn-Dox) specifically bound and subsequently internalized into tumor cells via interaction with overexpressed transferrin receptor 1 and released Dox in the lysosomes. In vivo in the mouse, HFn-Dox exhibited more than 10-fold higher intratumoral drug concentration than free Dox and significantly inhibited tumor growth after a single-dose injection. Importantly, HFn-Dox displayed an excellent safety profile that significantly reduced healthy organ drug exposure and improved the maximum tolerated dose by fourfold compared with free Dox. Moreover, because the HFn nanocarrier has well-defined morphology and does not need any ligand modification or property modulation it can be easily produced with high purity and yield, which are requirements for drugs used in clinical trials. Thus, these unique properties make the HFn nanocage an ideal vehicle for efficient anticancer drug delivery.
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Miller PS, Aricescu AR. Crystal structure of a human GABAA receptor. Nature 2014; 512:270-5. [PMID: 24909990 PMCID: PMC4167603 DOI: 10.1038/nature13293] [Citation(s) in RCA: 531] [Impact Index Per Article: 53.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Accepted: 03/28/2014] [Indexed: 01/01/2023]
Abstract
Type-A γ-aminobutyric acid receptors (GABAARs) are the principal mediators of rapid inhibitory synaptic transmission in the human brain. A decline in GABAAR signalling triggers hyperactive neurological disorders such as insomnia, anxiety and epilepsy. Here we present the first three-dimensional structure of a GABAAR, the human β3 homopentamer, at 3 Å resolution. This structure reveals architectural elements unique to eukaryotic Cys-loop receptors, explains the mechanistic consequences of multiple human disease mutations and shows an unexpected structural role for a conserved N-linked glycan. The receptor was crystallized bound to a previously unknown agonist, benzamidine, opening a new avenue for the rational design of GABAAR modulators. The channel region forms a closed gate at the base of the pore, representative of a desensitized state. These results offer new insights into the signalling mechanisms of pentameric ligand-gated ion channels and enhance current understanding of GABAergic neurotransmission.
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Affiliation(s)
- Paul S Miller
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - A Radu Aricescu
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
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21
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Bu W, Pereira LM, Eckenhoff RG, Yuki K. Stereoselectivity of isoflurane in adhesion molecule leukocyte function-associated antigen-1. PLoS One 2014; 9:e96649. [PMID: 24801074 PMCID: PMC4011845 DOI: 10.1371/journal.pone.0096649] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 04/09/2014] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Isoflurane in clinical use is a racemate of S- and R-isoflurane. Previous studies have demonstrated that the effects of S-isoflurane on relevant anesthetic targets might be modestly stronger (less than 2-fold) than R-isoflurane. The X-ray crystallographic structure of the immunological target, leukocyte function-associated antigen-1 (LFA-1) with racemic isoflurane suggested that only S-isoflurane bound specifically to this protein. If so, the use of specific isoflurane enantiomers may have advantage in the surgical settings where a wide range of inflammatory responses is expected to occur. Here, we have further tested the hypothesis that isoflurane enantioselectivity is apparent in solution binding and functional studies. METHODS First, binding of isoflurane enantiomers to LFA-1 was studied using 1-aminoanthracene (1-AMA) displacement assays. The binding site of each enantiomer on LFA-1 was studied using the docking program GLIDE. Functional studies employed the flow-cytometry based ICAM binding assay. RESULTS Both enantiomers decreased 1-AMA fluorescence signal (at 520 nm), indicating that both competed with 1-AMA and bound to the αL I domain. The docking simulation demonstrated that both enantiomers bound to the LFA-1 "lovastatin site." ICAM binding assays showed that S-isoflurane inhibited more potently than R-isoflurane, consistent with the result of 1-AMA competition assay. CONCLUSIONS In contrast with the x-ray crystallography, both enantiomers bound to and inhibited LFA-1. S-isoflurane showed slight preference over R-isoflurane.
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Affiliation(s)
- Weiming Bu
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Luis M. Pereira
- Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Boston, Massachusetts, United States of America
- Department of Anaesthesia, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Roderic G. Eckenhoff
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Koichi Yuki
- Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Boston, Massachusetts, United States of America
- Department of Anaesthesia, Harvard Medical School, Boston, Massachusetts, United States of America
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Weiser BP, Woll KA, Dailey WP, Eckenhoff RG. Mechanisms revealed through general anesthetic photolabeling. CURRENT ANESTHESIOLOGY REPORTS 2013; 4:57-66. [PMID: 24563623 DOI: 10.1007/s40140-013-0040-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
General anesthetic photolabels are used to reveal molecular targets and molecular binding sites of anesthetic ligands. After identification, the relevance of anesthetic substrates or binding sites can be tested in biological systems. Halothane and photoactive analogs of isoflurane, propofol, etomidate, neurosteroids, anthracene, and long chain alcohols have been used in anesthetic photolabeling experiments. Interrogated protein targets include the nicotinic acetylcholine receptor, GABAA receptor, tubulin, leukocyte function-associated antigen-1, and protein kinase C. In this review, we summarize insights revealed by photolabeling these targets, as well as general features of anesthetics, such as their propensity to partition to mitochondria and bind voltage-dependent anion channels. The theory of anesthetic photolabel design and the experimental application of photoactive ligands are also discussed.
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Affiliation(s)
- Brian P Weiser
- Department of Anesthesiology & Critical Care, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, Philadelphia, PA 19104 ; Department of Pharmacology, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, Philadelphia, PA 19104
| | - Kellie A Woll
- Department of Anesthesiology & Critical Care, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, Philadelphia, PA 19104 ; Department of Pharmacology, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, Philadelphia, PA 19104
| | - William P Dailey
- Department of Chemistry, University of Pennsylvania School of Arts and Sciences, 231 S. 34th Street, Philadelphia, PA 19104
| | - Roderic G Eckenhoff
- Department of Anesthesiology & Critical Care, University of Pennsylvania Perelman School of Medicine, 3620 Hamilton Walk, Philadelphia, PA 19104
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Yuki K, Bu W, Xi J, Shimaoka M, Eckenhoff R. Propofol shares the binding site with isoflurane and sevoflurane on leukocyte function-associated antigen-1. Anesth Analg 2013; 117:803-811. [PMID: 23960033 DOI: 10.1213/ane.0b013e3182a00ae0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND We previously demonstrated that propofol interacted with the leukocyte adhesion molecule leukocyte function-associated antigen-1 (LFA-1) and inhibited the production of interleukin-2 via LFA-1 in a dependent manner. However, the binding site(s) of propofol on LFA-1 remains unknown. METHODS First, the inhibition of LFA-1's ligand binding by propofol was confirmed in an enzyme-linked immunosorbent assay (ELISA) ELISA-type assay. The binding site of propofol on LFA-1 was probed with a photolabeling experiment using a photoactivatable propofol analog called azi-propofol-m. The adducted residues of LFA-1 by this compound were determined using liquid chromatography-mass spectrometry. In addition, the binding of propofol to the ligand-binding domain of LFA-1 was examined using 1-aminoanthracene (1-AMA) displacement assay. Furthermore, the binding site(s) of 1-AMA and propofol on LFA-1 was studied using the docking program GLIDE. RESULTS We demonstrated that propofol impaired the binding of LFA-1 to its ligand intercellular adhesion molecule-1. The photolabeling experiment demonstrated that the adducted residues were localized in the allosteric cavity of the ligand-binding domain of LFA-1 called "lovastatin site." The shift of fluorescence spectra was observed when 1-AMA was coincubated with the low-affinity conformer of LFA-1 ligand-binding domain (wild-type [WT] αL I domain), not with the high-affinity conformer, suggesting that 1-AMA bound only to WT αL I domain. In the 1-AMA displacement assay, propofol decreased 1-AMA fluorescence signal (at 520 nm), suggesting that propofol competed with 1-AMA and bound to the WT αL I domain. The docking simulation demonstrated that both 1-AMA and propofol bound to the lovastatin site, which agreed with the photolabeling experiment. CONCLUSIONS We demonstrated that propofol bound to the lovastatin site in LFA-1. Previously we showed that the volatile anesthetics isoflurane and sevoflurane bound to this site. Taken together, the lovastatin site is an example of the common binding sites for anesthetics currently used clinically.
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Affiliation(s)
- Koichi Yuki
- Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, 300 Longwood Ave., Boston, MA 02115.
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Emerson DJ, Weiser BP, Psonis J, Liao Z, Taratula O, Fiamengo A, Wang X, Sugasawa K, Smith AB, Eckenhoff RG, Dmochowski IJ. Direct modulation of microtubule stability contributes to anthracene general anesthesia. J Am Chem Soc 2013; 135:5389-98. [PMID: 23484901 DOI: 10.1021/ja311171u] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Recently, we identified 1-aminoanthracene as a fluorescent general anesthetic. To investigate the mechanism of action, a photoactive analogue, 1-azidoanthracene, was synthesized. Administration of 1-azidoanthracene to albino stage 40-47 tadpoles was found to immobilize animals upon near-UV irradiation of the forebrain region. The immobilization was often reversible, but it was characterized by a longer duration consistent with covalent attachment of the ligand to functionally important targets. IEF/SDS-PAGE examination of irradiated tadpole brain homogenate revealed labeled protein, identified by mass spectrometry as β-tubulin. In vitro assays with aminoanthracene-cross-linked tubulin indicated inhibition of microtubule polymerization, similar to colchicine. Tandem mass spectrometry confirmed anthracene binding near the colchicine site. Stage 40-47 tadpoles were also incubated 1 h with microtubule stabilizing agents, epothilone D or discodermolide, followed by dosing with 1-aminoanthracene. The effective concentration of 1-aminoanthracene required to immobilize the tadpoles was significantly increased in the presence of either microtubule stabilizing agent. Epothilone D similarly mitigated the effects of a clinical neurosteroid general anesthetic, allopregnanolone, believed to occupy the colchicine site in tubulin. We conclude that neuronal microtubules are "on-pathway" targets for anthracene general anesthetics and may also represent functional targets for some neurosteroid general anesthetics.
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Affiliation(s)
- Daniel J Emerson
- Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, USA
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Chitilian HV, Eckenhoff RG, Raines DE. Anesthetic drug development: Novel drugs and new approaches. Surg Neurol Int 2013; 4:S2-S10. [PMID: 23653886 PMCID: PMC3642742 DOI: 10.4103/2152-7806.109179] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Accepted: 08/08/2012] [Indexed: 12/17/2022] Open
Abstract
The ideal sedative–hypnotic drug would be a rapidly titratable intravenous agent with a high therapeutic index and minimal side effects. The current efforts to develop such agents are primarily focused on modifying the structures of existing drugs to improve their pharmacodynamic and pharmacokinetic properties. Drugs currently under development using this rational design approach include analogues of midazolam, propofol, and etomidate, such as remimazolam, PF0713, and cyclopropyl methoxycarbonyl-etomidate (MOC-etomidate), respectively. An alternative approach involves the rapid screening of large libraries of molecules for activity in structural or phenotypic assays that approximate anesthetic and target receptor interactions. Such high-throughput screening offers the potential for identifying completely novel classes of drugs. Anesthetic drug development is experiencing a resurgence of interest because there are new demands on our clinical practice that can be met, at least in part, with better agents. The goal of this review is to provide the reader with a glimpse of the novel anesthetic drugs and new developmental approaches that lie on the horizon.
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Affiliation(s)
- Hovig V Chitilian
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA
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Casalini T, Masi M, Perale G. Drug eluting sutures: A model for in vivo estimations. Int J Pharm 2012; 429:148-57. [DOI: 10.1016/j.ijpharm.2012.03.024] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Revised: 03/12/2012] [Accepted: 03/13/2012] [Indexed: 10/28/2022]
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Homma R, Yamashita H, Funaki J, Ueda R, Sakurai T, Ishimaru Y, Abe K, Asakura T. Identification of bitterness-masking compounds from cheese. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2012; 60:4492-4499. [PMID: 22502602 PMCID: PMC3399598 DOI: 10.1021/jf300563n] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Revised: 04/07/2012] [Accepted: 04/13/2012] [Indexed: 05/31/2023]
Abstract
Bitterness-masking compounds were identified in a natural white mold cheese. The oily fraction of the cheese was extracted and further fractionated by using silica gel column chromatography. The four fractions obtained were characterized by thin-layer chromatography and nuclear magnetic resonance spectroscopy. The fatty acid-containing fraction was found to have the highest bitterness-masking activity against quinine hydrochloride. Bitterness-masking activity was quantitated using a method based on subjective equivalents. At 0.5 mM, the fatty acid mixture, which had a composition similar to that of cheese, suppressed the bitterness of 0.008% quinine hydrochloride to be equivalent to that of 0.0049-0.0060% and 0.5 mM oleic acid to that of 0.0032-0.0038% solution. The binding potential between oleic acid and the bitter compounds was estimated by isothermal titration calorimetry. These results suggest that oleic acid masked bitterness by forming a complex with the bitter compounds.
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Affiliation(s)
- Ryousuke Homma
- Department of Applied
Biological Chemistry, Graduate School of Agricultural
and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Haruyuki Yamashita
- Department of Applied
Biological Chemistry, Graduate School of Agricultural
and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Junko Funaki
- International College
of Arts and Sciences, Fukuoka Women’s
University, 1-1-1 Kasumigaoka, Higashi-ku, Fukuoka 813-8529,
Japan
| | - Reiko Ueda
- Department of Applied
Biological Chemistry, Graduate School of Agricultural
and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Takanobu Sakurai
- General Research Institute of Food Science and Technology, Nissin Foods Holdings Company, Ltd., 7-4-1 Nojihigashi, Kusatsu-shi, Shiga 525-0058, Japan
| | - Yoshiro Ishimaru
- Department of Applied
Biological Chemistry, Graduate School of Agricultural
and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Keiko Abe
- Department of Applied
Biological Chemistry, Graduate School of Agricultural
and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Tomiko Asakura
- Department of Applied
Biological Chemistry, Graduate School of Agricultural
and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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Liu R, Bu W, Xi J, Mortazavi SR, Cheung-Lau JC, Dmochowski IJ, Loll PJ. Beyond the detergent effect: a binding site for sodium dodecyl sulfate (SDS) in mammalian apoferritin. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2012; 68:497-504. [PMID: 22525747 PMCID: PMC3335284 DOI: 10.1107/s0907444912002740] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Accepted: 01/21/2012] [Indexed: 11/10/2022]
Abstract
Although sodium dodecyl sulfate (SDS) is widely used as an anionic detergent, it can also exert specific pharmacological effects that are independent of the surfactant properties of the molecule. However, structural details of how proteins recognize SDS are scarce. Here, it is demonstrated that SDS binds specifically to a naturally occurring four-helix bundle protein: horse apoferritin. The X-ray crystal structure of the apoferritin-SDS complex was determined at a resolution of 1.9 Å and revealed that the SDS binds in an internal cavity that has previously been shown to recognize various general anesthetics. A dissociation constant of 24 ± 9 µM at 293 K was determined by isothermal titration calorimetry. SDS binds in this cavity by bending its alkyl tail into a horseshoe shape; the charged SDS head group lies in the opening of the cavity at the protein surface. This crystal structure provides insights into the protein-SDS interactions that give rise to binding and may prove useful in the design of novel SDS-like ligands for some proteins.
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Affiliation(s)
- Renyu Liu
- Department of Anesthesia and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Weiming Bu
- Department of Anesthesia and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Jin Xi
- Department of Anesthesia and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Shirin R. Mortazavi
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
| | - Jasmina C. Cheung-Lau
- Department of Anesthesia and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Ivan J. Dmochowski
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Patrick J. Loll
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
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Recognition of anesthetic barbiturates by a protein binding site: a high resolution structural analysis. PLoS One 2012; 7:e32070. [PMID: 22359658 PMCID: PMC3281113 DOI: 10.1371/journal.pone.0032070] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 01/23/2012] [Indexed: 01/30/2023] Open
Abstract
Barbiturates potentiate GABA actions at the GABAA receptor and act as central nervous system depressants that can induce effects ranging from sedation to general anesthesia. No structural information has been available about how barbiturates are recognized by their protein targets. For this reason, we tested whether these drugs were able to bind specifically to horse spleen apoferritin, a model protein that has previously been shown to bind many anesthetic agents with affinities that are closely correlated with anesthetic potency. Thiopental, pentobarbital, and phenobarbital were all found to bind to apoferritin with affinities ranging from 10–500 µM, approximately matching the concentrations required to produce anesthetic and GABAergic responses. X-ray crystal structures were determined for the complexes of apoferritin with thiopental and pentobarbital at resolutions of 1.9 and 2.0 Å, respectively. These structures reveal that the barbiturates bind to a cavity in the apoferritin shell that also binds haloalkanes, halogenated ethers, and propofol. Unlike these other general anesthetics, however, which rely entirely upon van der Waals interactions and the hydrophobic effect for recognition, the barbiturates are recognized in the apoferritin site using a mixture of both polar and nonpolar interactions. These results suggest that any protein binding site that is able to recognize and respond to the chemically and structurally diverse set of compounds used as general anesthetics is likely to include a versatile mixture of both polar and hydrophobic elements.
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Giansanti V, Santamaria G, Torriglia A, Aredia F, Scovassi AI, Bottiroli G, Croce AC. Fluorescence properties of the Na⁺/H⁺exchanger inhibitor HMA (5-(N,N-hexamethylene)amiloride) are modulated by intracellular pH. Eur J Histochem 2012; 56:e3. [PMID: 22472891 PMCID: PMC3352132 DOI: 10.4081/ejh.2012.e3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Revised: 11/21/2011] [Accepted: 11/24/2011] [Indexed: 11/22/2022] Open
Abstract
HMA (5-(N,N-hexamethylene)amiloride), which belongs to a family of novel amiloride derivatives, is one of the most effective inhibitors of Na+/H+ exchangers, while uneffective against Na+ channels and Na+/Ca2+ exchangers. In this study, we provided evidence that HMA can act as a fluorescent probe. In fact, human retinal ARPE19 cells incubated with HMA show an intense bluish fluorescence in the cytoplasm when observed at microscope under conventional UV-excitation conditions. Interestingly, a prolonged observation under continuous exposure to excitation lightdoes not induce great changes in cells incubated with HMA for times up to about 5 min, while an unexpected rapid increase in fluorescence signal is observed in cells incubated for longer times. The latter phenomenon is particularly evident in the perinuclear region and in discrete spots in the cytoplasm. Since HMA modulates intracellular acidity, the dependence of its fluorescence properties on medium pH and response upon irradiation have been investigated in solution, at pH 5.0 and pH 7.2. The changes in both spectral shape and amplitude emission indicate a marked pH influence on HMA fluorescence properties, making HMA exploitable as a self biomarker of pH alterations in cell studies, in the absence of perturbations induced by the administration of other exogenous dyes.
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31
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Krasowski MD, Hopfinger AJ. The discovery of new anesthetics by targeting GABAAreceptors. Expert Opin Drug Discov 2011; 6:1187-201. [DOI: 10.1517/17460441.2011.627324] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Abstract
Over the last several decades, the average age of patients has steadily increased, whereas the use of general anesthesia and deep sedation has grown largely outside the operating room environment. Currently available general anesthetics and delivery models represent limitations in addressing these trends. At the same time, research has tremendously expanded the knowledge of how general anesthetics produce their beneficial effects and also revealed evidence of previously unappreciated general anesthetic toxicities. The goal of this review is to highlight these important developments and describe translational research on new general anesthetics with the potential to improve and reshape clinical care.
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Affiliation(s)
- Stuart A Forman
- Department of Anesthesia, Critical Care & Pain Medicine, Massachusetts General Hospital, Jackson 4, MGH, 55 Fruit Street, Boston, MA 02114, USA.
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33
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Vanderweyde T, Bednar MM, Forman SA, Wolozin B. Iatrogenic risk factors for Alzheimer's disease: surgery and anesthesia. J Alzheimers Dis 2011; 22 Suppl 3:91-104. [PMID: 20858967 DOI: 10.3233/jad-2010-100843] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Increasing evidence indicates that patients develop post-operative cognitive decline (POCD) following surgery. POCD is characterized by transient short-term decline in cognitive ability evident in the early post-operative period. This initial decline might be associated with increased risk of a delayed cognitive decline associated with dementia 3 to 5 years post-surgery. In some studies, the conversion rates to dementia are up to 70% in patients who are 65 years or older. The factors responsible for the increased risk of dementia are unclear; however, clinical studies investigating the prevalence of POCD and dementia following surgery do not show an association with the type of anesthesia or duration of surgery. Epidemiological studies from our group support this observation. The adjusted Hazard Ratios for developing dementia (or AD specifically) after prostate or hernia surgery were 0.65 (95% CI, 0.51 to 0.83, prostate) and 0.65 (95% CI, 0.49 to 0.85, hernia) for cohorts of subjects exposed to general anesthesia compared to those exposed only to local anesthesia. Animal studies suggest that prolonged exposure to some volatile-inhalational anesthetics increase production of amyloid-β and vulnerability to neurodegeneration, but these results are weakened by the absence of clinical support. Inflammation and a maladaptive stress response might also contribute to the pathophysiology of this disorder. Future research needs to identify predisposing factors, and then strategies to protect against POCD and subsequent dementia. The field also needs to adopt a more rigorous approach to codifying the frequency and extent of early and delayed post-operative cognitive decline.
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Affiliation(s)
- Tara Vanderweyde
- Department of Pharmacology, Boston University School of Medicine, MA 021182526, USA
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34
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Falconer RJ, Collins BM. Survey of the year 2009: applications of isothermal titration calorimetry. J Mol Recognit 2010; 24:1-16. [DOI: 10.1002/jmr.1073] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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35
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Hall MA, Xi J, Lor C, Dai S, Pearce R, Dailey WP, Eckenhoff RG. m-Azipropofol (AziPm) a photoactive analogue of the intravenous general anesthetic propofol. J Med Chem 2010; 53:5667-75. [PMID: 20597506 PMCID: PMC2917171 DOI: 10.1021/jm1004072] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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Propofol is the most commonly used sedative-hypnotic drug for noxious procedures, yet the molecular targets underlying either its beneficial or toxic effects remain uncertain. In order to determine targets and thereby mechanisms of propofol, we have synthesized a photoactivateable analogue by substituting an alkyldiazirinyl moiety for one of the isopropyl arms but in the meta position. m-Azipropofol retains the physical, biochemical, GABAA receptor modulatory, and in vivo activity of propofol and photoadducts to amino acid residues in known propofol binding sites in natural proteins. Using either mass spectrometry or radiolabeling, this reagent may be used to reveal sites and targets that underlie the mechanism of both the desirable and undesirable actions of this important clinical compound.
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Affiliation(s)
- Michael A Hall
- Department of Anesthesiology and Critical Care, University of Pennsylvania School of Medicine, Philadelphia,Pennsylvania, USA
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36
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Hénin J, Brannigan G, Dailey WP, Eckenhoff R, Klein ML. An atomistic model for simulations of the general anesthetic isoflurane. J Phys Chem B 2010; 114:604-12. [PMID: 19924847 DOI: 10.1021/jp9088035] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An atomistic model of isoflurane is constructed and calibrated to describe its conformational preferences and intermolecular interactions. The model, which is compatible with the CHARMM force field for biomolecules, is based on target quantities including bulk liquid properties, molecular conformations, and local interactions with isolated water molecules. Reference data is obtained from tabulated thermodynamic properties and high-resolution structural information from gas-phase electron diffraction, as well as DFT calculations at the B3LYP level. The model is tested against experimentally known solvation properties in water and oil, and shows quantitative agreement. In particular, isoflurane is faithfully described as lipophilic, yet nonhydrophobic, a combination of properties critical to its pharmacological activity. Intermolecular interactions of the model are further probed through simulations of the binding of isoflurane to a binding site in horse spleen apoferritin (HSAF). The observed binding mode compares well with crystallographic data, and the calculated binding affinities are compatible with experimental results, although both computational and experimental measurements are challenging and provide results with limited precision. The model is expected to be useful for detailed simulations of the elementary molecular processes associated with anesthesia. Full parameters are provided as Supporting Information.
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Affiliation(s)
- Jérôme Hénin
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, CNRS, Marseille, France.
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37
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Eckenhoff RG, Xi J, Shimaoka M, Bhattacharji A, Covarrubias M, Dailey WP. Azi-isoflurane, a Photolabel Analog of the Commonly Used Inhaled General Anesthetic Isoflurane. ACS Chem Neurosci 2010; 1:139-145. [PMID: 20228895 PMCID: PMC2837340 DOI: 10.1021/cn900014m] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2009] [Accepted: 09/28/2009] [Indexed: 11/30/2022] Open
Abstract
Volatility and low-affinity hamper an ability to define molecular targets of the inhaled anesthetics. Photolabels have proven to be a useful approach in this regard, although none have closely mimicked contemporary drugs. We report here the synthesis and validation of azi-isoflurane, a compound constructed by adding a diazirinyl moiety to the methyl carbon of the commonly used general anesthetic isoflurane. Azi-isoflurane is slightly more hydrophobic than isoflurane, and more potent in tadpoles. This novel compound inhibits Shaw2 K(+) channel currents similarly to isoflurane and binds to apoferritin with enhanced affinity. Finally, when irradiated at 300 nm, azi-isoflurane adducts to residues known to line isoflurane-binding sites in apoferritin and integrin LFA-1, the only proteins with isoflurane binding sites defined by crystallography. This reagent should allow rapid discovery of isoflurane molecular targets and binding sites within those targets.
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Affiliation(s)
| | - Jin Xi
- Department of Anesthesiology & Critical Care, School of Medicine
| | - Motomu Shimaoka
- Immune Disease Institute; Molecular & Cellular Medicine, Children’s Hospital Boston, and Department of Anesthesia, Harvard Medical School, Boston, Massachusetts
| | - Aditya Bhattacharji
- Department of Pathology, Anatomy & Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Manuel Covarrubias
- Department of Pathology, Anatomy & Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania
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38
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Zhang Y, Raudah S, Teo H, Teo GWS, Fan R, Sun X, Orner BP. Alanine-shaving mutagenesis to determine key interfacial residues governing the assembly of a nano-cage maxi-ferritin. J Biol Chem 2010; 285:12078-86. [PMID: 20139406 DOI: 10.1074/jbc.m109.092445] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The fundamental process of protein self-assembly is governed by protein-protein interactions between subunits, which combine to form structures that are often on the nano-scale. The nano-cage protein, bacterioferritin from Escherichia coli, a maxi-ferritin made up of 24 subunits, was chosen as the basis for an alanine-shaving mutagenesis study to discover key amino acid residues at symmetry-related protein-protein interfaces that control protein stability and self-assembly. By inspection of these interfaces and "virtual alanine scanning," nine mutants were designed, expressed, purified, and characterized using transmission electron microscopy, size exclusion chromatography, dynamic light scattering, native PAGE, and temperature-dependent CD. Many of the selected amino acids act as hot spot residues. Four of these (Arg-30, which is located at the two-fold axis, and Arg-61, Tyr-114, and Glu-128, which are located at the three-fold axis), when individually mutated to alanine, completely shut down detectable solution formation of 24-mer, favoring a cooperatively folded dimer, suggesting that they may be oligomerization "switch residues." Furthermore, two residues, Arg-30 and Arg-61, when changed to alanine form mutants that are more thermodynamically stable than the native protein. This investigation into the structure and energetics of this self-assembling nano-cage protein not only can act as a jumping off point for the eventual design of novel protein nano-structures but can also help to understand the role that structure plays on the function of this important class of proteins.
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Affiliation(s)
- Yu Zhang
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore
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39
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Vemparala S, Domene C, Klein ML. Computational studies on the interactions of inhalational anesthetics with proteins. Acc Chem Res 2010; 43:103-10. [PMID: 19788306 DOI: 10.1021/ar900149j] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Despite the widespread clinical use of anesthetics since the 19th century, a clear understanding of the mechanism of anesthetic action has yet to emerge. On the basis of early experiments by Meyer, Overton, and subsequent researchers, the cell's lipid membrane was generally concluded to be the primary site of action of anesthetics. However, later experiments with lipid-free globular proteins, such as luciferase and apoferritin, shifted the focus of anesthetic action to proteins. Recent experimental studies, such as photoaffinity labeling and mutagenesis on membrane proteins, have suggested specific binding sites for anesthetic molecules, further strengthening the proteocentric view of anesthetic mechanism. With the increased availability of high-resolution crystal structures of ion channels and other integral membrane proteins, as well as the availability of powerful computers, the structure-function relationship of anesthetic-protein interactions can now be investigated in atomic detail. In this Account, we review recent experiments and related computer simulation studies involving interactions of inhalational anesthetics and proteins, with a particular focus on membrane proteins. Globular proteins have long been used as models for understanding the role of protein-anesthetic interactions and are accordingly examined in this Account. Using selected examples of membrane proteins, such as nicotinic acetyl choline receptor (nAChR) and potassium channels, we address the issues of anesthetic binding pockets in proteins, the role of conformation in anesthetic effects, and the modulation of local as well as global dynamics of proteins by inhaled anesthetics. In the case of nicotinic receptors, inhalational anesthetic halothane binds to the hydrophobic cavity close to the M2-M3 loop. This binding modulates the dynamics of the M2-M3 loop, which is implicated in allosterically transmitting the effects to the channel gate, thus altering the function of the protein. In potassium channels, anesthetic molecules preferentially potentiate the open conformation by quenching the motion of the aromatic residues implicated in the gating of the channel. These simulations suggest that low-affinity drugs (such as inhalational anesthetics) modulate the protein function by influencing local as well as global dynamics of proteins. Because of intrinsic experimental limitations, computational approaches represent an important avenue for exploring the mode of action of anesthetics. Molecular dynamics simulations-a computational technique frequently used in the general study of proteins-offer particular insight in the study of the interaction of inhalational anesthetics with membrane proteins.
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Affiliation(s)
- Satyavani Vemparala
- The Institute of Mathematical Sciences, C.I.T Campus, Taramani, Chennai 600 113, India
| | - Carmen Domene
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3QZ U.K
| | - Michael L. Klein
- Center for Molecular Modeling and Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323
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40
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Lea WA, Xi J, Jadhav A, Lu L, Austin CP, Simeonov A, Eckenhoff RG. A high-throughput approach for identification of novel general anesthetics. PLoS One 2009; 4:e7150. [PMID: 19777064 PMCID: PMC2746312 DOI: 10.1371/journal.pone.0007150] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Accepted: 08/23/2009] [Indexed: 11/18/2022] Open
Abstract
Anesthetic development has been a largely empirical process. Recently, we described a GABAergic mimetic model system for anesthetic binding, based on apoferritin and an environment-sensitive fluorescent probe. Here, a competition assay based on 1-aminoanthracene and apoferritin has been taken to a high throughput screening level, and validated using the LOPAC(1280) library of drug-like compounds. A raw hit rate of approximately 15% was reduced through the use of computational filters to yield an overall hit rate of approximately 1%. These hits were validated using isothermal titration calorimetry. The success of this initial screen and computational triage provides feasibility to undergo a large scale campaign to discover novel general anesthetics.
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Affiliation(s)
- Wendy A. Lea
- NIH Chemical Genomics Center, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Jin Xi
- Department. of Anesthesiology & Critical Care, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Ajit Jadhav
- NIH Chemical Genomics Center, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Louis Lu
- Department. of Anesthesiology & Critical Care, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Christopher P. Austin
- NIH Chemical Genomics Center, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Anton Simeonov
- NIH Chemical Genomics Center, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail: (RGE); (AS)
| | - Roderic G. Eckenhoff
- Department. of Anesthesiology & Critical Care, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
- * E-mail: (RGE); (AS)
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41
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Vedula LS, Brannigan G, Economou NJ, Xi J, Hall MA, Liu R, Rossi MJ, Dailey WP, Grasty KC, Klein ML, Eckenhoff RG, Loll PJ. A unitary anesthetic binding site at high resolution. J Biol Chem 2009; 284:24176-84. [PMID: 19605349 DOI: 10.1074/jbc.m109.017814] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Propofol is the most widely used injectable general anesthetic. Its targets include ligand-gated ion channels such as the GABA(A) receptor, but such receptor-channel complexes remain challenging to study at atomic resolution. Until structural biology methods advance to the point of being able to deal with systems such as the GABA(A) receptor, it will be necessary to use more tractable surrogates to probe the molecular details of anesthetic recognition. We have previously shown that recognition of inhalational general anesthetics by the model protein apoferritin closely mirrors recognition by more complex and clinically relevant protein targets; here we show that apoferritin also binds propofol and related GABAergic anesthetics, and that the same binding site mediates recognition of both inhalational and injectable anesthetics. Apoferritin binding affinities for a series of propofol analogs were found to be strongly correlated with the ability to potentiate GABA responses at GABA(A) receptors, validating this model system for injectable anesthetics. High resolution x-ray crystal structures reveal that, despite the presence of hydrogen bond donors and acceptors, anesthetic recognition is mediated largely by van der Waals forces and the hydrophobic effect. Molecular dynamics simulations indicate that the ligands undergo considerable fluctuations about their equilibrium positions. Finally, apoferritin displays both structural and dynamic responses to anesthetic binding, which may mimic changes elicited by anesthetics in physiologic targets like ion channels.
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Affiliation(s)
- L Sangeetha Vedula
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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42
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Structure-based shape pharmacophore modeling for the discovery of novel anesthetic compounds. Bioorg Med Chem 2009; 17:5133-8. [DOI: 10.1016/j.bmc.2009.05.060] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2009] [Revised: 05/18/2009] [Accepted: 05/22/2009] [Indexed: 11/24/2022]
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