1
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Kim ED, Wu X, Lee S, Tibbs GR, Cunningham KP, Di Zanni E, Perez ME, Goldstein PA, Accardi A, Larsson HP, Nimigean CM. Propofol rescues voltage-dependent gating of HCN1 channel epilepsy mutants. Nature 2024; 632:451-459. [PMID: 39085604 DOI: 10.1038/s41586-024-07743-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 06/20/2024] [Indexed: 08/02/2024]
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels1 are essential for pacemaking activity and neural signalling2,3. Drugs inhibiting HCN1 are promising candidates for management of neuropathic pain4 and epileptic seizures5. The general anaesthetic propofol (2,6-di-iso-propylphenol) is a known HCN1 allosteric inhibitor6 with unknown structural basis. Here, using single-particle cryo-electron microscopy and electrophysiology, we show that propofol inhibits HCN1 by binding to a mechanistic hotspot in a groove between the S5 and S6 transmembrane helices. We found that propofol restored voltage-dependent closing in two HCN1 epilepsy-associated polymorphisms that act by destabilizing the channel closed state: M305L, located in the propofol-binding site in S5, and D401H in S6 (refs. 7,8). To understand the mechanism of propofol inhibition and restoration of voltage-gating, we tracked voltage-sensor movement in spHCN channels and found that propofol inhibition is independent of voltage-sensor conformational changes. Mutations at the homologous methionine in spHCN and an adjacent conserved phenylalanine in S6 similarly destabilize closing without disrupting voltage-sensor movements, indicating that voltage-dependent closure requires this interface intact. We propose a model for voltage-dependent gating in which propofol stabilizes coupling between the voltage sensor and pore at this conserved methionine-phenylalanine interface in HCN channels. These findings unlock potential exploitation of this site to design specific drugs targeting HCN channelopathies.
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Affiliation(s)
- Elizabeth D Kim
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA
| | - Xiaoan Wu
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Sangyun Lee
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA
| | - Gareth R Tibbs
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA
| | - Kevin P Cunningham
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA
- School of Life Sciences, University of Westminster, London, UK
| | - Eleonora Di Zanni
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA
| | - Marta E Perez
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Peter A Goldstein
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA
| | - Alessio Accardi
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY, USA
| | - H Peter Larsson
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA.
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden.
| | - Crina M Nimigean
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA.
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY, USA.
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2
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Vukalović J, Marinković BP, Rosado J, Blanco F, García G, Maljković JB. Investigating theoretical and experimental cross sections for elastic electron scattering from isoflurane. Phys Chem Chem Phys 2024; 26:985-991. [PMID: 38088093 DOI: 10.1039/d3cp05052a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2024]
Abstract
We present a comprehensive analysis of elastic electron scattering from isoflurane in the intermediate energy range of 50-300 eV. This research is motivated by the significant impact of this molecule on global warming effects. We conducted this investigation through experimental measurements using a crossed-beam apparatus and covering a wide angular range from 25 to 125 degrees. Relative differential cross sections (DCSs) were obtained and subsequently normalized on an absolute scale by using the relative flow technique, with argon as the reference gas. These DCS values were then extrapolated and integrated to determine the experimental integral cross sections (ICSs). Additionally, we employed the independent atom model and the screening corrected additivity rule with incorporated Interference effects (IAM-SCAR+I) to calculate the theoretical differential and integral cross-sections. Remarkably, the calculated cross sections align closely with the experimental measurements across the entire energy and angular range. Furthermore, this study involved a comparison of the DCSs for isoflurane with previously published DCS values for two other volatile anesthetics, sevoflurane and halothane.
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Affiliation(s)
- Jelena Vukalović
- Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, Belgrade, 11080, Serbia.
- Faculty of Science, University of Banja Luka, Mladena Stojanovic'a 2, 78000 Banja Luka, Republic of Srpska, Bosnia and Herzegovina.
| | - Bratislav P Marinković
- Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, Belgrade, 11080, Serbia.
| | - Jaime Rosado
- Departamento de Física Atómica Molecular y Nuclear, Facultad de Ciencias Físicas, Universidad Complutense, Avda. Complutense s/n, E-28040 Madrid, Spain
| | - Francisco Blanco
- Departamento de Física Atómica Molecular y Nuclear, Facultad de Ciencias Físicas, Universidad Complutense, Avda. Complutense s/n, E-28040 Madrid, Spain
| | - Gustavo García
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 121, 28006 Madrid, Spain
| | - Jelena B Maljković
- Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, Belgrade, 11080, Serbia.
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3
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Sharma A, Kumar V, Chakraborty S. Micro-Solvation of Propofol in Propylene Glycol-Water Binary Mixtures: Molecular Dynamics Simulation Studies. J Phys Chem B 2023; 127:11011-11022. [PMID: 37972382 DOI: 10.1021/acs.jpcb.3c04932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Abstract
The water microstructure around propofol plays a crucial role in controlling their solubility in the binary mixture. The unusual nature of such a water microstructure can influence both translational and reorientational dynamics, as well as the water hydrogen bond network near propofol. We have carried out all-atom molecular dynamics simulations of five different compositions of the propylene glycol (PG)/water binary mixture containing propofol (PFL) molecules to investigate the differential behavior of water microsolvation shells around propofol, which is likely to control the propofol solubility. It is evident from the simulation snapshots for various compositions that the PG at high molecular ratio favors the water cluster and extended chainlike network that percolates within the PG matrix, where the propofol is in the dispersed state. We estimated that the radial distribution function indicates higher ordered water microstructure around propofol for high PG content, as compared to the lower PG content in the PG/water mixture. So, the hydrophilic PG regulates the stability of the water micronetwork around propofol and its solubility in the binary mixture. We observed that the translational and rotational mobility of water belonging to the propofol microsolvation shell is hindered for high PG content and relaxed toward the low PG molecular ratio in the PG/water mixture. It has been noticed that the structural relaxation of the hydrogen bond formed between the propofol and the water molecules present in the propofol microsolvation shell for all five compositions is found to be slower for high PG content and becomes faster on the way to low PG content in the mixture. Simultaneously, we calculated the intermittent residence time correlation function of the water molecules belonging to the microsolvation shell around the propofol for five different compositions and found a faster short time decay followed up with long time components. Again, the origin of such long time decay is primarily from the structural relaxation of the microsolvation shell around the propofol, where the high PG content shows the slower structural relaxation that turns faster as the PG content approaches to the other end of the compositions. So, our studies showed that the slower structural relaxation of the microsolvation shell around propofol for a high PG molecular ratio in the PG/water mixture correlate well with the extensive ordering of the water microstructure and restricted water mobility and facilitates the dissolution process of propofol in the binary mixture.
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Affiliation(s)
- Anupama Sharma
- Department of Computational Sciences, School of Basic Sciences, Central University of Punjab, Bathinda 151401, India
| | - Vishal Kumar
- Department of Computational Sciences, School of Basic Sciences, Central University of Punjab, Bathinda 151401, India
| | - Sudip Chakraborty
- Department of Computational Sciences, School of Basic Sciences, Central University of Punjab, Bathinda 151401, India
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4
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Kim G, Kim H, Jang IS. Trichloroethanol, an active metabolite of chloral hydrate, modulates tetrodotoxin-resistant Na + channels in rat nociceptive neurons. BMC Anesthesiol 2023; 23:145. [PMID: 37120567 PMCID: PMC10148498 DOI: 10.1186/s12871-023-02105-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 04/22/2023] [Indexed: 05/01/2023] Open
Abstract
BACKGROUND Chloral hydrate is a sedative-hypnotic drug widely used for relieving fear and anxiety in pediatric patients. However, mechanisms underlying the chloral hydrate-mediated analgesic action remain unexplored. Therefore, we investigated the effect of 2',2',2'-trichloroethanol (TCE), the active metabolite of chloral hydrate, on tetrodotoxin-resistant (TTX-R) Na+ channels expressed in nociceptive sensory neurons. METHODS The TTX-R Na+ current (INa) was recorded from acutely isolated rat trigeminal ganglion neurons using the whole-cell patch-clamp technique. RESULTS Trichloroethanol decreased the peak amplitude of transient TTX-R INa in a concentration-dependent manner and potently inhibited persistent components of transient TTX-R INa and slow voltage-ramp-induced INa at clinically relevant concentrations. Trichloroethanol exerted multiple effects on various properties of TTX-R Na+ channels; it (1) induced a hyperpolarizing shift on the steady-state fast inactivation relationship, (2) increased use-dependent inhibition, (3) accelerated the onset of inactivation, and (4) retarded the recovery of inactivated TTX-R Na+ channels. Under current-clamp conditions, TCE increased the threshold for the generation of action potentials, as well as decreased the number of action potentials elicited by depolarizing current stimuli. CONCLUSIONS Our findings suggest that chloral hydrate, through its active metabolite TCE, inhibits TTX-R INa and modulates various properties of these channels, resulting in the decreased excitability of nociceptive neurons. These pharmacological characteristics provide novel insights into the analgesic efficacy exerted by chloral hydrate.
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Affiliation(s)
- Gimin Kim
- Department of Pediatric Dentistry, School of Dentistry, Kyungpook National University, Daegu, 41940, Republic of Korea
| | - Hyunjung Kim
- Department of Pediatric Dentistry, School of Dentistry, Kyungpook National University, Daegu, 41940, Republic of Korea
| | - Il-Sung Jang
- Department of Pharmacology, School of Dentistry, Kyungpook National University, 2177 Dalgubeol-daero, Jung-gu, Daegu, 41940, Republic of Korea.
- Brain Science & Engineering Institute, Kyungpook National University, Daegu, 41940, Republic of Korea.
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5
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Mechanisms underlying drug-mediated regulation of membrane protein function. Proc Natl Acad Sci U S A 2021; 118:2113229118. [PMID: 34753824 DOI: 10.1073/pnas.2113229118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/20/2021] [Indexed: 11/18/2022] Open
Abstract
The hydrophobic coupling between membrane proteins and their host lipid bilayer provides a mechanism by which bilayer-modifying drugs may alter protein function. Drug regulation of membrane protein function thus may be mediated by both direct interactions with the protein and drug-induced alterations of bilayer properties, in which the latter will alter the energetics of protein conformational changes. To tease apart these mechanisms, we examine how the prototypical, proton-gated bacterial potassium channel KcsA is regulated by bilayer-modifying drugs using a fluorescence-based approach to quantify changes in both KcsA function and lipid bilayer properties (using gramicidin channels as probes). All tested drugs inhibited KcsA activity, and the changes in the different gating steps varied with bilayer thickness, suggesting a coupling to the bilayer. Examining the correlations between changes in KcsA gating steps and bilayer properties reveals that drug-induced regulation of membrane protein function indeed involves bilayer-mediated mechanisms. Both direct, either specific or nonspecific, binding and bilayer-mediated mechanisms therefore are likely to be important whenever there is overlap between the concentration ranges at which a drug alters membrane protein function and bilayer properties. Because changes in bilayer properties will impact many diverse membrane proteins, they may cause indiscriminate changes in protein function.
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6
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Róg T, Girych M, Bunker A. Mechanistic Understanding from Molecular Dynamics in Pharmaceutical Research 2: Lipid Membrane in Drug Design. Pharmaceuticals (Basel) 2021; 14:1062. [PMID: 34681286 PMCID: PMC8537670 DOI: 10.3390/ph14101062] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 10/14/2021] [Accepted: 10/15/2021] [Indexed: 11/17/2022] Open
Abstract
We review the use of molecular dynamics (MD) simulation as a drug design tool in the context of the role that the lipid membrane can play in drug action, i.e., the interaction between candidate drug molecules and lipid membranes. In the standard "lock and key" paradigm, only the interaction between the drug and a specific active site of a specific protein is considered; the environment in which the drug acts is, from a biophysical perspective, far more complex than this. The possible mechanisms though which a drug can be designed to tinker with physiological processes are significantly broader than merely fitting to a single active site of a single protein. In this paper, we focus on the role of the lipid membrane, arguably the most important element outside the proteins themselves, as a case study. We discuss work that has been carried out, using MD simulation, concerning the transfection of drugs through membranes that act as biological barriers in the path of the drugs, the behavior of drug molecules within membranes, how their collective behavior can affect the structure and properties of the membrane and, finally, the role lipid membranes, to which the vast majority of drug target proteins are associated, can play in mediating the interaction between drug and target protein. This review paper is the second in a two-part series covering MD simulation as a tool in pharmaceutical research; both are designed as pedagogical review papers aimed at both pharmaceutical scientists interested in exploring how the tool of MD simulation can be applied to their research and computational scientists interested in exploring the possibility of a pharmaceutical context for their research.
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Affiliation(s)
- Tomasz Róg
- Department of Physics, University of Helsinki, 00014 Helsinki, Finland;
| | - Mykhailo Girych
- Department of Physics, University of Helsinki, 00014 Helsinki, Finland;
| | - Alex Bunker
- Drug Research Program, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, 00014 Helsinki, Finland;
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7
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Towards Quantum-Chemical Modeling of the Activity of Anesthetic Compounds. Int J Mol Sci 2021; 22:ijms22179272. [PMID: 34502179 PMCID: PMC8431746 DOI: 10.3390/ijms22179272] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 08/16/2021] [Accepted: 08/17/2021] [Indexed: 12/16/2022] Open
Abstract
The modeling of the activity of anesthetics is a real challenge because of their unique electronic and structural characteristics. Microscopic approaches relevant to the typical features of these systems have been developed based on the advancements in the theory of intermolecular interactions. By stressing the quantum chemical point of view, here, we review the advances in the field highlighting differences and similarities among the chemicals within this group. The binding of the anesthetics to their partners has been analyzed by Symmetry-Adapted Perturbation Theory to provide insight into the nature of the interaction and the modeling of the adducts/complexes allows us to rationalize their anesthetic properties. A new approach in the frame of microtubule concept and the importance of lipid rafts and channels in membranes is also discussed.
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8
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Michaels W, Zhao Y, Qin J. Atomistic Modeling of PEDOT:PSS Complexes II: Force Field Parameterization. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c00860] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Wesley Michaels
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States
| | - Yan Zhao
- Department of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430070, China
| | - Jian Qin
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States
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9
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Wang Y, Ming XX, Zhang CP. Fluorine-Containing Inhalation Anesthetics: Chemistry, Properties and Pharmacology. Curr Med Chem 2020; 27:5599-5652. [DOI: 10.2174/0929867326666191003155703] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 08/27/2019] [Accepted: 09/05/2019] [Indexed: 02/07/2023]
Abstract
Studies on fluorinated inhalation anesthetics, including synthesis, physical chemistry and
pharmacology, have been summarized in this review. Retrospecting the history of inhalation anesthetics
revealed their increasing reliance on fluorine and ether structures. Halothane causes a rare but
severe immune-based hepatotoxicity, which was replaced by enflurane in the 1970s. Isoflurane replaced
enflurane in the 1980s, showing modest advantages (e.g. lower solubility, better metabolic
stability, and without convulsive predisposition). Desflurane and sevoflurane came into use in the
1990s, which are better anesthetics than isoflurane (less hepatotoxicity, lower solubility, and/or
markedly decreased pungency). However, they are still less than perfect. To gain more ideal inhalation
anesthetics, a large number of fluorinated halocarbons, polyfluorocycloalkanes, polyfluorocycloalkenes,
fluoroarenes, and polyfluorooxetanes, were prepared and their potency and toxicity were
evaluated. Although the pharmacology studies suggested that some of these agents produced anesthesia,
no further studies were continued on these compounds because they showed obvious lacking
as anesthetics. Moreover, the anesthetic activity cannot be simply predicted from the molecular
structures but has to be inferred from the experiments. Several regularities were found by experimental
studies: 1) the potency and toxicity of the saturated linear chain halogenated ether are enhanced
when its molecular weight is increased; 2) the margin of safety decreases and the recovery
time is prolonged when the boiling point of the candidate increases; and 3) compounds with an
asymmetric carbon terminal exhibit good anesthesia. Nevertheless, the development of new inhalation
anesthetics, better than desflurane and sevoflurane, is still challenging not only because of the
poor structure/activity relationship known so far but also due to synthetic issues.
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Affiliation(s)
- Yuzhong Wang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, 237 Luoyu Road, Wuhan 430079, China
| | - Xiao-Xia Ming
- School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, 205 Luoshi Road, Wuhan 430070, China
| | - Cheng-Pan Zhang
- School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, 205 Luoshi Road, Wuhan 430070, China
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10
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Shahoei R, Tajkhorshid E. Menthol Binding to the Human α4β2 Nicotinic Acetylcholine Receptor Facilitated by Its Strong Partitioning in the Membrane. J Phys Chem B 2020; 124:1866-1880. [PMID: 32048843 PMCID: PMC7094167 DOI: 10.1021/acs.jpcb.9b10092] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We utilize various computational methodologies to study menthol's interaction with multiple organic phases, a lipid bilayer, and the human α4β2 nicotinic acetylcholine receptor (nAChR), the most abundant nAChR in the brain. First, force field parameters developed for menthol are validated in alchemical free energy perturbation simulations to calculate solvation free energies of menthol in water, dodecane, and octanol and compare the results against experimental data. Next, umbrella sampling is used to construct the free energy profile of menthol permeation across a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayer. The results from a flooding simulation designed to study the water-membrane partitioning of menthol in a POPC lipid bilayer are used to determine the penetration depth and the preferred orientation of menthol in the bilayer. Finally, employing both docking and flooding simulations, menthol is shown to bind to different sites on the human α4β2 nAChR. The most likely binding mode of menthol to a desensitized membrane-embedded α4β2 nAChR is identified to be via a membrane-mediated pathway in which menthol binds to the sites at the lipid-protein interface after partitioning in the membrane. A rare but distinct binding mode in which menthol binds to the extracellular opening of receptor's ion permeation pore is also reported.
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Affiliation(s)
- Rezvan Shahoei
- Department of Physics, NIH Center for Macromolecular Modeling and Bioinformatics, and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Emad Tajkhorshid
- Department of Biochemistry, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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11
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Patel J, Chowdhury EA, Noorani B, Bickel U, Huang J. Isoflurane increases cell membrane fluidity significantly at clinical concentrations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1862:183140. [PMID: 31790694 DOI: 10.1016/j.bbamem.2019.183140] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Revised: 11/18/2019] [Accepted: 11/27/2019] [Indexed: 01/17/2023]
Abstract
There is an on-going debate whether anesthetic drugs, such as isoflurane, can cause meaningful structural changes in cell membranes at clinical concentrations. In this study, the effects of isoflurane on lipid membrane fluidity were investigated using fluorescence anisotropy and spectroscopy. In order to get a complete picture, four very different membrane systems (erythrocyte ghosts, a 5-lipid mixture that mimics brain endothelial cell membrane, POPC/Chol, and pure DPPC) were selected for the study. In all four systems, we found that fluorescence anisotropies of DPH-PC, nile-red, and TMA-DPH decrease significantly at the isoflurane concentrations of 1 mM and 5 mM. Furthermore, the excimer/monomer (E/M) ratio of dipyrene-PC jumps immediately after the addition of isoflurane. We found that isoflurane is quite effective to loosen up highly ordered lipid domains with saturated lipids. Interestingly, 1 mM isoflurane causes a larger decrease of nile-red fluorescence anisotropy in erythrocyte ghosts than 52.2 mM of ethanol, which is three times the legal limit of blood alcohol level. Our results paint a consistent picture that isoflurane at clinical concentrations causes significant and immediate increase of membrane fluidity in a wide range of membrane systems.
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Affiliation(s)
- Jigesh Patel
- Department of Physics and Astronomy, Texas Tech University, Lubbock, TX 79409, United States of America
| | - Ekram A Chowdhury
- Department of Pharmaceutical Sciences, Texas Tech University Health Science Center, Amarillo, TX 79106, United States of America
| | - Behnam Noorani
- Department of Pharmaceutical Sciences, Texas Tech University Health Science Center, Amarillo, TX 79106, United States of America
| | - Ulrich Bickel
- Department of Pharmaceutical Sciences, Texas Tech University Health Science Center, Amarillo, TX 79106, United States of America
| | - Juyang Huang
- Department of Physics and Astronomy, Texas Tech University, Lubbock, TX 79409, United States of America.
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12
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Burdick RK, Villabona-Monsalve JP, Mashour GA, Goodson T. Modern Anesthetic Ethers Demonstrate Quantum Interactions with Entangled Photons. Sci Rep 2019; 9:11351. [PMID: 31383882 PMCID: PMC6683176 DOI: 10.1038/s41598-019-47651-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 07/08/2019] [Indexed: 11/09/2022] Open
Abstract
Despite decades of research, the mechanism of anesthetic-induced unconsciousness remains incompletely understood, with some advocating for a quantum mechanical basis. Despite associations between general anesthesia and changes in physical properties such as electron spin, there has been no empirical demonstration that general anesthetics are capable of functional quantum interactions. In this work, we studied the linear and non-linear optical properties of the halogenated ethers sevoflurane (SEVO) and isoflurane (ISO), using UV-Vis spectroscopy, time dependent-density functional theory (TD-DFT) calculations, classical two-photon spectroscopy, and entangled two-photon spectroscopy. We show that both of these halogenated ethers interact with pairs of 800 nm entangled photons while neither interact with 800 nm classical photons. By contrast, nonhalogenated diethyl ether does not interact with entangled photons. This is the first experimental evidence that halogenated anesthetics can directly undergo quantum interaction mechanisms, offering a new approach to understanding their physicochemical properties.
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Affiliation(s)
- Ryan K Burdick
- Department of Chemistry, University of Michigan, Ann Arbor, MI, 48109, USA
| | | | - George A Mashour
- Center for Consciousness Science, Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, 48109-5048, USA.
| | - Theodore Goodson
- Department of Chemistry, University of Michigan, Ann Arbor, MI, 48109, USA.
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13
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Yang H, Li H, Liu L, Zhou Y, Long X. Molecular Simulation Studies on the Interactions of 2,4,6-Trinitrotoluene and Its Metabolites with Lipid Membranes. J Phys Chem B 2019; 123:6481-6491. [DOI: 10.1021/acs.jpcb.9b03033] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Hong Yang
- School of Material Science and Engineering, Tsinghua University, Beijing 100084, China
- Institute of Chemical Materials, China Academy of Engineering and Physics, Mianyang 621900, China
| | - Huarong Li
- Institute of Chemical Materials, China Academy of Engineering and Physics, Mianyang 621900, China
| | - Liu Liu
- Institute of Chemical Materials, China Academy of Engineering and Physics, Mianyang 621900, China
| | - Yang Zhou
- Institute of Chemical Materials, China Academy of Engineering and Physics, Mianyang 621900, China
| | - Xinping Long
- Institute of Chemical Materials, China Academy of Engineering and Physics, Mianyang 621900, China
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14
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Enkavi G, Javanainen M, Kulig W, Róg T, Vattulainen I. Multiscale Simulations of Biological Membranes: The Challenge To Understand Biological Phenomena in a Living Substance. Chem Rev 2019; 119:5607-5774. [PMID: 30859819 PMCID: PMC6727218 DOI: 10.1021/acs.chemrev.8b00538] [Citation(s) in RCA: 175] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Indexed: 12/23/2022]
Abstract
Biological membranes are tricky to investigate. They are complex in terms of molecular composition and structure, functional over a wide range of time scales, and characterized by nonequilibrium conditions. Because of all of these features, simulations are a great technique to study biomembrane behavior. A significant part of the functional processes in biological membranes takes place at the molecular level; thus computer simulations are the method of choice to explore how their properties emerge from specific molecular features and how the interplay among the numerous molecules gives rise to function over spatial and time scales larger than the molecular ones. In this review, we focus on this broad theme. We discuss the current state-of-the-art of biomembrane simulations that, until now, have largely focused on a rather narrow picture of the complexity of the membranes. Given this, we also discuss the challenges that we should unravel in the foreseeable future. Numerous features such as the actin-cytoskeleton network, the glycocalyx network, and nonequilibrium transport under ATP-driven conditions have so far received very little attention; however, the potential of simulations to solve them would be exceptionally high. A major milestone for this research would be that one day we could say that computer simulations genuinely research biological membranes, not just lipid bilayers.
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Affiliation(s)
- Giray Enkavi
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Matti Javanainen
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy
of Sciences, Flemingovo naḿesti 542/2, 16610 Prague, Czech Republic
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
| | - Waldemar Kulig
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Tomasz Róg
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
| | - Ilpo Vattulainen
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
- MEMPHYS-Center
for Biomembrane Physics
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15
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Hantal G, Fábián B, Sega M, Jójárt B, Jedlovszky P. Effect of general anesthetics on the properties of lipid membranes of various compositions. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1861:594-609. [PMID: 30571949 DOI: 10.1016/j.bbamem.2018.12.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 12/05/2018] [Accepted: 12/13/2018] [Indexed: 10/27/2022]
Abstract
Computer simulations of four lipid membranes of different compositions, namely neat DPPC and PSM, and equimolar DPPC-cholesterol and PSM-cholesterol mixtures, are performed in the presence and absence of the general anesthetics diethylether and sevoflurane both at 1 and 600 bar. The results are analyzed in order to identify membrane properties that are potentially related to the molecular mechanism of anesthesia, namely that change in the same way in any membrane with any anesthetics, and change oppositely with increasing pressure. We find that the lateral lipid density satisfies both criteria: it is decreased by anesthetics and increased by pressure. This anesthetic-induced swelling is attributed to only those anesthetic molecules that are located close to the boundary of the apolar phase. This lateral expansion is found to lead to increased lateral mobility of the lipids, an effect often thought to be related to general anesthesia; to an increased fraction of the free volume around the outer preferred position of anesthetics; and to the decrease of the lateral pressure in the nearby range of the ester and amide groups, a region into which anesthetic molecules already cannot penetrate. All these changes are reverted by the increase of pressure. Another important finding of this study is that cholesterol has an opposite effect on the membrane properties than anesthetics, and, correspondingly, these changes are less marked in the presence of cholesterol. Therefore, changes in the membrane that can lead to general anesthesia are expected to occur in the membrane domains of low cholesterol content.
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Affiliation(s)
- György Hantal
- Faculty of Physics, University of Vienna, Sensengasse 8/9, A-1090 Vienna, Austria
| | - Balázs Fábián
- Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Szt. Gellért tér 4, H-1111 Budapest, Hungary; Institut UTINAM (CNRS UMR 6213), Université Bourgogne Franche-Comté, 16 route de Gray, F-25030 Besançon, France
| | - Marcello Sega
- Faculty of Physics, University of Vienna, Sensengasse 8/9, A-1090 Vienna, Austria
| | - Balázs Jójárt
- Institute of Food Engineering, University of Szeged, Moszkvai krt 5-7, H-6725 Szeged, Hungary
| | - Pál Jedlovszky
- Department of Chemistry, Eszterházy Károly University, Leányka utca 6, H-3300 Eger, Hungary.
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16
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Kiametis A, Stock L, Cirqueira L, Treptow W. Atomistic Model for Simulations of the Sedative Hypnotic Drug 2,2,2-Trichloroethanol. ACS OMEGA 2018; 3:15916-15923. [PMID: 30556017 PMCID: PMC6288786 DOI: 10.1021/acsomega.8b02017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 11/08/2018] [Indexed: 05/16/2023]
Abstract
2,2,2-Trichloroethanol (TCE) is the active form of the sedative hypnotic drug chloral hydrate, one of the oldest sleep medications in the market. Understanding of TCE's action mechanisms to its many targets, particularly within the ion channel family, could benefit from the state-of-the-art computational molecular studies. In this direction, we employed de novo modeling aided by the force field toolkit to develop CHARMM36-compatible TCE parameters. The classical potential energy function was calibrated targeting molecular conformations, local interactions with water molecules, and liquid bulk properties. Reference data comes from both tabulated thermodynamic properties and ab initio calculations at the MP2 level. TCE solvation free energy calculations in water and oil reproduce a lipophilic, yet nonhydrophobic, behavior. Indeed, the potential mean force profile for TCE partition through the phospholipid bilayer reveals the sedative's preference for the interfacial region. The calculated partition coefficient also matches experimental measures. Further validation of the proposed parameters is supported by the model's ability to recapitulate quenching experiments demonstrating TCE binding to bovine serum albumin.
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17
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Stock L, Hosoume J, Cirqueira L, Treptow W. Binding of the general anesthetic sevoflurane to ion channels. PLoS Comput Biol 2018; 14:e1006605. [PMID: 30475796 PMCID: PMC6283617 DOI: 10.1371/journal.pcbi.1006605] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 12/06/2018] [Accepted: 10/26/2018] [Indexed: 11/21/2022] Open
Abstract
The direct-site hypothesis assumes general anesthetics bind ion channels to impact protein equilibrium and function, inducing anesthesia. Despite advancements in the field, a first principle all-atom demonstration of this structure-function premise is still missing. We focus on the clinically used sevoflurane interaction to anesthetic-sensitive Kv1.2 mammalian channel to resolve if sevoflurane binds protein’s well-characterized open and closed structures in a conformation-dependent manner to shift channel equilibrium. We employ an innovative approach relying on extensive docking calculations and free-energy perturbation of all potential binding sites revealed by the latter, and find sevoflurane binds open and closed structures at multiple sites under complex saturation and concentration effects. Results point to a non-trivial interplay of site and conformation-dependent modes of action involving distinct binding sites that increase channel open-probability at diluted ligand concentrations. Given the challenge in exploring more complex processes potentially impacting channel-anesthetic interaction, the result is revealing as it demonstrates the process of multiple anesthetic binding events alone may account for open-probability shifts recorded in measurements. General anesthetics are central to modern medicine, yet their microscopic mechanism of action is still unknown. Here, we demonstrate that a clinically used anesthetic, sevoflurane, binds the mammalian voltage-gated potassium channel Kv1.2 effecting a shift in its open probability, even at low concentrations. The results, supported by recent experimental measurements, are promising as they demonstrate that the molecular process of direct binding of anesthetic to ion channels play a relevant role in anesthesia.
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Affiliation(s)
- Letícia Stock
- Laboratório de Biologia Teórica e Computacional (LBTC), Universidade de Brasília DF, Brasil
| | - Juliana Hosoume
- Laboratório de Biologia Teórica e Computacional (LBTC), Universidade de Brasília DF, Brasil
| | - Leonardo Cirqueira
- Laboratório de Biologia Teórica e Computacional (LBTC), Universidade de Brasília DF, Brasil
| | - Werner Treptow
- Laboratório de Biologia Teórica e Computacional (LBTC), Universidade de Brasília DF, Brasil
- * E-mail:
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18
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Oakes V, Domene C. Capturing the Molecular Mechanism of Anesthetic Action by Simulation Methods. Chem Rev 2018; 119:5998-6014. [DOI: 10.1021/acs.chemrev.8b00366] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Victoria Oakes
- Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
| | - Carmen Domene
- Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
- Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom
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19
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Jorgensen C, Domene C. Location and Character of Volatile General Anesthetics Binding Sites in the Transmembrane Domain of TRPV1. Mol Pharm 2018; 15:3920-3930. [PMID: 30067911 DOI: 10.1021/acs.molpharmaceut.8b00381] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
It has been proposed that general anesthesia results from direct multisite interactions with multiple and diverse ion channels in the brain. An understanding of the mechanisms by which general anesthetics modulate ion channels is essential to clarify their underlying behavior and their role in reversible immobilization and amnesia. Despite the fact that volatile general anesthetics are drugs that primarily induce insensitivity to pain, they have been reported to sensitize and active the vanilloid-1 receptor, TRPV1, which is known to mediate the response of the nervous system to certain harmful stimuli and which plays a crucial role in the pain pathway. Currently, the mechanism of action of anesthetics is unknown and the precise molecular sites of interaction have not been identified. Here, using ∼2.5 μs of classical molecular dynamics simulations and metadynamics, we explore these enigmas. Binding sites are identified and the strength of the association is further characterized using alchemical free-energy calculations. Anesthetic binding/unbinding proceeds primarily through a membrane-embedded pathway, and subsequently, a complex scenario is established involving multiple binding sites featuring single or multiple occupancy states of two small volatile drugs. One of the five anesthetic binding sites reported was previously identified experimentally, and another one, importantly, is identical to that of capsaicin, one of the chemical stimuli that activate TRPV1. However, in contrast to capsaicin, isoflurane and chloroform binding free-energies render modest to no association compared to capsaicin, suggesting a different activation mechanism. Uncovering chloroform and isoflurane modulatory sites will further our understanding of the TRPV1 molecular machinery and open the possibility of developing site-specific drugs.
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Affiliation(s)
- Christian Jorgensen
- Department of Chemistry , King's College London , Britannia House, 7 Trinity Street , London SE1 1DB , U.K
| | - Carmen Domene
- Department of Chemistry , King's College London , Britannia House, 7 Trinity Street , London SE1 1DB , U.K.,Department of Chemistry , University of Bath , 1 South Building, Claverton Down , Bath BA2 7AY , U.K.,Chemistry Research Laboratory , University of Oxford , Mansfield Road , Oxford OX1 3TA , U.K
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20
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Arcario MJ, Mayne CG, Tajkhorshid E. A membrane-embedded pathway delivers general anesthetics to two interacting binding sites in the Gloeobacter violaceus ion channel. J Biol Chem 2017; 292:9480-9492. [PMID: 28420728 PMCID: PMC5465477 DOI: 10.1074/jbc.m117.780197] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 04/10/2017] [Indexed: 12/30/2022] Open
Abstract
General anesthetics exert their effects on the central nervous system by acting on ion channels, most notably pentameric ligand-gated ion channels. Although numerous studies have focused on pentameric ligand-gated ion channels, the details of anesthetic binding and channel modulation are still debated. A better understanding of the anesthetic mechanism of action is necessary for the development of safer and more efficacious drugs. Herein, we present a computational study identifying two anesthetic binding sites in the transmembrane domain of the Gloeobacter violaceus ligand-gated ion channel (GLIC) channel, characterize the putative binding pathway, and observe structural changes associated with channel function. Molecular simulations of desflurane reveal a binding pathway to GLIC via a membrane-embedded tunnel using an intrasubunit protein lumen as the conduit, an observation that explains the Meyer-Overton hypothesis, or why the lipophilicity of an anesthetic and its potency are generally proportional. Moreover, employing high concentrations of ligand led to the identification of a second transmembrane site (TM2) that inhibits dissociation of anesthetic from the TM1 site and is consistent with the high concentrations of anesthetics required to achieve clinical effects. Finally, asymmetric binding patterns of anesthetic to the channel were found to promote an iris-like conformational change that constricts and dehydrates the ion pore, creating a 13.5 kcal/mol barrier to ion translocation. Together with previous studies, the simulations presented herein demonstrate a novel anesthetic binding site in GLIC that is accessed through a membrane-embedded tunnel and interacts with a previously known site, resulting in conformational changes that produce a non-conductive state of the channel.
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Affiliation(s)
- Mark J Arcario
- From the Center for Biophysics and Quantitative Biology.,Department of Biochemistry, College of Medicine, and.,Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Christopher G Mayne
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Emad Tajkhorshid
- From the Center for Biophysics and Quantitative Biology, .,Department of Biochemistry, College of Medicine, and.,Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
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21
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Clinical concentrations of chemically diverse general anesthetics minimally affect lipid bilayer properties. Proc Natl Acad Sci U S A 2017; 114:3109-3114. [PMID: 28265069 DOI: 10.1073/pnas.1611717114] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
General anesthetics have revolutionized medicine by facilitating invasive procedures, and have thus become essential drugs. However, detailed understanding of their molecular mechanisms remains elusive. A mechanism proposed over a century ago involving unspecified interactions with the lipid bilayer known as the unitary lipid-based hypothesis of anesthetic action, has been challenged by evidence for direct anesthetic interactions with a range of proteins, including transmembrane ion channels. Anesthetic concentrations in the membrane are high (10-100 mM), however, and there is no experimental evidence ruling out a role for the lipid bilayer in their ion channel effects. A recent hypothesis proposes that anesthetic-induced changes in ion channel function result from changes in bilayer lateral pressure that arise from partitioning of anesthetics into the bilayer. We examined the effects of a broad range of chemically diverse general anesthetics and related nonanesthetics on lipid bilayer properties using an established fluorescence assay that senses drug-induced changes in lipid bilayer properties. None of the compounds tested altered bilayer properties sufficiently to produce meaningful changes in ion channel function at clinically relevant concentrations. Even supra-anesthetic concentrations caused minimal bilayer effects, although much higher (toxic) concentrations of certain anesthetic agents did alter lipid bilayer properties. We conclude that general anesthetics have minimal effects on bilayer properties at clinically relevant concentrations, indicating that anesthetic effects on ion channel function are not bilayer-mediated but rather involve direct protein interactions.
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22
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Lopes D, Jakobtorweihen S, Nunes C, Sarmento B, Reis S. Shedding light on the puzzle of drug-membrane interactions: Experimental techniques and molecular dynamics simulations. Prog Lipid Res 2017; 65:24-44. [DOI: 10.1016/j.plipres.2016.12.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 11/30/2016] [Accepted: 12/03/2016] [Indexed: 12/20/2022]
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23
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Wang H, Meng F. Molecular simulation study on concentration effects of rofecoxib with POPC bilayer. J Mol Graph Model 2016; 70:94-99. [DOI: 10.1016/j.jmgm.2016.09.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 09/21/2016] [Accepted: 09/22/2016] [Indexed: 10/21/2022]
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24
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Mayne CG, Arcario MJ, Mahinthichaichan P, Baylon JL, Vermaas JV, Navidpour L, Wen PC, Thangapandian S, Tajkhorshid E. The cellular membrane as a mediator for small molecule interaction with membrane proteins. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1858:2290-2304. [PMID: 27163493 PMCID: PMC4983535 DOI: 10.1016/j.bbamem.2016.04.016] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 04/26/2016] [Accepted: 04/27/2016] [Indexed: 01/05/2023]
Abstract
The cellular membrane constitutes the first element that encounters a wide variety of molecular species to which a cell might be exposed. Hosting a large number of structurally and functionally diverse proteins associated with this key metabolic compartment, the membrane not only directly controls the traffic of various molecules in and out of the cell, it also participates in such diverse and important processes as signal transduction and chemical processing of incoming molecular species. In this article, we present a number of cases where details of interaction of small molecular species such as drugs with the membrane, which are often experimentally inaccessible, have been studied using advanced molecular simulation techniques. We have selected systems in which partitioning of the small molecule with the membrane constitutes a key step for its final biological function, often binding to and interacting with a protein associated with the membrane. These examples demonstrate that membrane partitioning is not only important for the overall distribution of drugs and other small molecules into different compartments of the body, it may also play a key role in determining the efficiency and the mode of interaction of the drug with its target protein. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg.
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Affiliation(s)
- Christopher G Mayne
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, United States.
| | - Mark J Arcario
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, United States; Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, United States; College of Medicine, University of Illinois at Urbana-Champaign, United States.
| | - Paween Mahinthichaichan
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, United States; Department of Biochemistry, University of Illinois at Urbana-Champaign, United States.
| | - Javier L Baylon
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, United States; Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, United States.
| | - Josh V Vermaas
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, United States; Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, United States.
| | - Latifeh Navidpour
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, United States.
| | - Po-Chao Wen
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, United States.
| | - Sundarapandian Thangapandian
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, United States; Department of Biochemistry, University of Illinois at Urbana-Champaign, United States.
| | - Emad Tajkhorshid
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, United States; Department of Biochemistry, University of Illinois at Urbana-Champaign, United States; Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, United States; College of Medicine, University of Illinois at Urbana-Champaign, United States.
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25
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Vermaas JV, Trebesch N, Mayne CG, Thangapandian S, Shekhar M, Mahinthichaichan P, Baylon JL, Jiang T, Wang Y, Muller MP, Shinn E, Zhao Z, Wen PC, Tajkhorshid E. Microscopic Characterization of Membrane Transporter Function by In Silico Modeling and Simulation. Methods Enzymol 2016; 578:373-428. [PMID: 27497175 PMCID: PMC6404235 DOI: 10.1016/bs.mie.2016.05.042] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Membrane transporters mediate one of the most fundamental processes in biology. They are the main gatekeepers controlling active traffic of materials in a highly selective and regulated manner between different cellular compartments demarcated by biological membranes. At the heart of the mechanism of membrane transporters lie protein conformational changes of diverse forms and magnitudes, which closely mediate critical aspects of the transport process, most importantly the coordinated motions of remotely located gating elements and their tight coupling to chemical processes such as binding, unbinding and translocation of transported substrate and cotransported ions, ATP binding and hydrolysis, and other molecular events fueling uphill transport of the cargo. An increasing number of functional studies have established the active participation of lipids and other components of biological membranes in the function of transporters and other membrane proteins, often acting as major signaling and regulating elements. Understanding the mechanistic details of these molecular processes require methods that offer high spatial and temporal resolutions. Computational modeling and simulations technologies empowered by advanced sampling and free energy calculations have reached a sufficiently mature state to become an indispensable component of mechanistic studies of membrane transporters in their natural environment of the membrane. In this article, we provide an overview of a number of major computational protocols and techniques commonly used in membrane transporter modeling and simulation studies. The article also includes practical hints on effective use of these methods, critical perspectives on their strengths and weak points, and examples of their successful applications to membrane transporters, selected from the research performed in our own laboratory.
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Affiliation(s)
- J V Vermaas
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - N Trebesch
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - C G Mayne
- University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - S Thangapandian
- University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - M Shekhar
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - P Mahinthichaichan
- University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - J L Baylon
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - T Jiang
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Y Wang
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - M P Muller
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; College of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - E Shinn
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Z Zhao
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - P-C Wen
- University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - E Tajkhorshid
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; University of Illinois at Urbana-Champaign, Urbana, IL, United States; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; College of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, United States.
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26
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Neale C, Pomès R. Sampling errors in free energy simulations of small molecules in lipid bilayers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2539-2548. [PMID: 26952019 DOI: 10.1016/j.bbamem.2016.03.006] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 03/01/2016] [Accepted: 03/02/2016] [Indexed: 12/14/2022]
Abstract
Free energy simulations are a powerful tool for evaluating the interactions of molecular solutes with lipid bilayers as mimetics of cellular membranes. However, these simulations are frequently hindered by systematic sampling errors. This review highlights recent progress in computing free energy profiles for inserting molecular solutes into lipid bilayers. Particular emphasis is placed on a systematic analysis of the free energy profiles, identifying the sources of sampling errors that reduce computational efficiency, and highlighting methodological advances that may alleviate sampling deficiencies. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg.
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Affiliation(s)
- Chris Neale
- Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, 110 8th St, Troy, New York 12180-3590, USA
| | - Régis Pomès
- Molecular Structure and Function, The Hospital for Sick Children, 686 Bay Street, Toronto, Ontario M5G 0A4, Canada; Department of Biochemistry, University of Toronto, 101 College Street, Toronto, Ontario M5G 1L7, Canada.
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27
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Macroscopic and macromolecular specificity of alkylphenol anesthetics for neuronal substrates. Sci Rep 2015; 5:9695. [PMID: 25853337 PMCID: PMC4894431 DOI: 10.1038/srep09695] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2014] [Accepted: 02/24/2015] [Indexed: 01/06/2023] Open
Abstract
We used a photoactive general anesthetic called meta-azi-propofol (AziPm) to test the selectivity and specificity of alkylphenol anesthetic binding in mammalian brain. Photolabeling of rat brain sections with [3H]AziPm revealed widespread but heterogeneous ligand distribution, with [3H]AziPm preferentially binding to synapse-dense areas compared to areas composed largely of cell bodies or myelin. With [3H]AziPm and propofol, we determined that alkylphenol general anesthetics bind selectively and specifically to multiple synaptic protein targets. In contrast, the alkylphenol anesthetics do not bind to specific sites on abundant phospholipids or cholesterol, although [3H]AziPm shows selectivity for photolabeling phosphatidylethanolamines. Together, our experiments suggest that alkylphenol anesthetic substrates are widespread in number and distribution, similar to those of volatile general anesthetics, and that multi-target mechanisms likely underlie their pharmacology.
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