1
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Chiramba C, Möller DS, Lorenz CD, Chirombo RR, Mason AJ, Bester MJ, Gaspar ARM. Tryptophan End-Tagging Confers Antifungal Activity on a Tick-Derived Peptide by Triggering Reactive Oxygen Species Production. ACS OMEGA 2024; 9:15556-15572. [PMID: 38585074 PMCID: PMC10993377 DOI: 10.1021/acsomega.4c00478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 02/26/2024] [Accepted: 03/07/2024] [Indexed: 04/09/2024]
Abstract
WHO has identified several Candida species including Candida albicans as critical priority fungal pathogens due to greater infection prevalence and formation of recalcitrant biofilms. Novel antifungal agents are urgently needed, and antimicrobial peptides (AMPs) are being considered as potential alternatives, but inactivity in physiological salt environments, serum, and plasma often limits further therapeutic development. Tryptophan end-tagging is a strategy to overcome these limitations and is thought to selectively enhance membrane permeabilization in both fungal and bacterial plasma membranes. Here, we show that C-terminal tryptophan end-tagging of the tick-derived peptide Os-C transforms an inactive peptide into Os-C(W5), an antifungal peptide capable of preventing the formation of C. albicans biofilms. Mechanistic insight is provided by circular dichroism spectroscopy and molecular dynamics simulations, which demonstrate that tryptophan end-tagging alters the secondary structure of Os-C, while the latter reveals that end-tagging reduces interactions with, and insertion into, a model C. albicans membrane but promotes peptide aggregation on its surface. Interestingly, this leads to the induction of reactive oxygen species production rather than membrane permeabilization, and consequently, oxidative stress leads to cell wall damage. Os-C(W5) does not induce the hemolysis of human erythrocytes. Reduced cell adhesion and viability contribute to decreased biofilm extracellular matrix formation which, although reduced, is retained in the serum-containing medium. In this study, tryptophan end-tagging was identified as a promising strategy for enhancing the antifungal activity, including the biofilm inhibitory activity of Os-C against C. albicans in physiological salt environments.
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Affiliation(s)
- Court
K. Chiramba
- Department
of Biochemistry, Genetics and Microbiology, Faculty of Natural and
Agricultural Sciences, University of Pretoria, Pretoria 0002, South Africa
| | - Dalton S. Möller
- Department
of Biochemistry, Genetics and Microbiology, Faculty of Natural and
Agricultural Sciences, University of Pretoria, Pretoria 0002, South Africa
| | | | - Rumbidzai R. Chirombo
- Department
of Anatomy, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa
| | - A. James Mason
- Institute
of Pharmaceutical Science, School of Cancer & Pharmaceutical Science, King’s College London, London SE1 9NH, U.K.
| | - Megan J. Bester
- Department
of Anatomy, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa
| | - Anabella R. M. Gaspar
- Department
of Biochemistry, Genetics and Microbiology, Faculty of Natural and
Agricultural Sciences, University of Pretoria, Pretoria 0002, South Africa
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2
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Venianakis T, Siskos M, Papamokos G, Gerothanassis IP. NMR and DFT studies of monounsaturated and ω-3 polyunsaturated free fatty acids in the liquid state reveal a novel atomistic structural model of DHA. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
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3
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Hammond OS, Atri R, Bowron DT, Edler KJ. Neutron Diffraction Study of Indole Solvation in Deep Eutectic Systems of Choline Chloride, Malic Acid, and Water. Chemistry 2022; 28:e202200566. [PMID: 35510678 PMCID: PMC9400976 DOI: 10.1002/chem.202200566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Indexed: 11/09/2022]
Abstract
Deep eutectic systems are currently under intense investigation to replace traditional organic solvents in a range of syntheses. Here, indole in choline chloride‐malic acid deep eutectic solvent (DES) was studied as a function of water content, to identify solute interactions with the DES which affect heterocycle reactivity and selectivity, and as a proxy for biomolecule solvation. Empirical Potential Structure Refinement models of neutron diffraction data showed [Cholinium]+ cations associate strongly with the indole π‐system due to electrostatics, whereas malic acid is only weakly associated. Trace water is sequestered into the DES and does not interact strongly with indole. When water is added to the DES, it does not interact with the indole π‐system but is exclusively in‐plane with the heterocyclic rings, forming strong H‐bonds with the ‐NH group, and also weak H‐bonds and thus prominent hydrophobic hydration of the indole aromatic region, which could direct selectivity in reactions.
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Affiliation(s)
- Oliver S. Hammond
- Centre for Sustainable Chemical Technologies and Department of Chemistry University of Bath Claverton Down Bath BA2 7AY U.K
- Current address: Department of Materials and Environmental Chemistry Stockholm University Stockholm Sweden
| | - Ria Atri
- Centre for Sustainable Chemical Technologies and Department of Chemical Engineering University of Bath Claverton Down Bath BA2 7AY U.K
| | - Daniel T. Bowron
- ISIS Neutron and Muon Source Science and Technology Facilities Council Rutherford Appleton Laboratory Didcot OX11 0QX U.K
| | - Karen J. Edler
- Centre for Sustainable Chemical Technologies and Department of Chemistry University of Bath Claverton Down Bath BA2 7AY U.K
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4
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Terban MW, Billinge SJL. Structural Analysis of Molecular Materials Using the Pair Distribution Function. Chem Rev 2022; 122:1208-1272. [PMID: 34788012 PMCID: PMC8759070 DOI: 10.1021/acs.chemrev.1c00237] [Citation(s) in RCA: 54] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Indexed: 12/16/2022]
Abstract
This is a review of atomic pair distribution function (PDF) analysis as applied to the study of molecular materials. The PDF method is a powerful approach to study short- and intermediate-range order in materials on the nanoscale. It may be obtained from total scattering measurements using X-rays, neutrons, or electrons, and it provides structural details when defects, disorder, or structural ambiguities obscure their elucidation directly in reciprocal space. While its uses in the study of inorganic crystals, glasses, and nanomaterials have been recently highlighted, significant progress has also been made in its application to molecular materials such as carbons, pharmaceuticals, polymers, liquids, coordination compounds, composites, and more. Here, an overview of applications toward a wide variety of molecular compounds (organic and inorganic) and systems with molecular components is presented. We then present pedagogical descriptions and tips for further implementation. Successful utilization of the method requires an interdisciplinary consolidation of material preparation, high quality scattering experimentation, data processing, model formulation, and attentive scrutiny of the results. It is hoped that this article will provide a useful reference to practitioners for PDF applications in a wide realm of molecular sciences, and help new practitioners to get started with this technique.
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Affiliation(s)
- Maxwell W. Terban
- Max
Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - Simon J. L. Billinge
- Department
of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, United States
- Condensed
Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, United States
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5
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Nasri Z, Memari S, Wenske S, Clemen R, Martens U, Delcea M, Bekeschus S, Weltmann K, von Woedtke T, Wende K. Singlet-Oxygen-Induced Phospholipase A 2 Inhibition: A Major Role for Interfacial Tryptophan Dioxidation. Chemistry 2021; 27:14702-14710. [PMID: 34375468 PMCID: PMC8596696 DOI: 10.1002/chem.202102306] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Indexed: 11/16/2022]
Abstract
Several studies have revealed that various diseases such as cancer have been associated with elevated phospholipase A2 (PLA2 ) activity. Therefore, the regulation of PLA2 catalytic activity is undoubtedly vital. In this study, effective inactivation of PLA2 due to reactive species produced from cold physical plasma as a source to model oxidative stress is reported. We found singlet oxygen to be the most relevant active agent in PLA2 inhibition. A more detailed analysis of the plasma-treated PLA2 identified tryptophan 128 as a hot spot, rich in double oxidation. The significant dioxidation of this interfacial tryptophan resulted in an N-formylkynurenine product via the oxidative opening of the tryptophan indole ring. Molecular dynamics simulation indicated that the efficient interactions between the tryptophan residue and phospholipids are eliminated following tryptophan dioxidation. As interfacial tryptophan residues are predominantly involved in the attaching of membrane enzymes to the bilayers, tryptophan dioxidation and indole ring opening leads to the loss of essential interactions for enzyme binding and, consequently, enzyme inactivation.
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Affiliation(s)
- Zahra Nasri
- Center for Innovation Competence (ZIK) plasmatisLeibniz Institute for Plasma Science and Technology (INP)Felix-Hausdorff-Straße 217489GreifswaldGermany
| | - Seyedali Memari
- Center for Innovation Competence (ZIK) plasmatisLeibniz Institute for Plasma Science and Technology (INP)Felix-Hausdorff-Straße 217489GreifswaldGermany
- Institute of Anatomy and Cell BiologyUniversity Medicine GreifswaldFriedrich-Loeffler-Straße 23cGreifswald17487Germany
| | - Sebastian Wenske
- Center for Innovation Competence (ZIK) plasmatisLeibniz Institute for Plasma Science and Technology (INP)Felix-Hausdorff-Straße 217489GreifswaldGermany
| | - Ramona Clemen
- Center for Innovation Competence (ZIK) plasmatisLeibniz Institute for Plasma Science and Technology (INP)Felix-Hausdorff-Straße 217489GreifswaldGermany
| | - Ulrike Martens
- Institute of BiochemistryUniversity of GreifswaldFelix-Hausdorff-Straße 4Greifswald17489Germany
- Center for Innovation Competence (ZIK) HIKE (Humoral Immune Reactions in Cardiovascular Diseases)University of GreifswaldGreifswaldFleischmannstraße 4217489Germany
| | - Mihaela Delcea
- Institute of BiochemistryUniversity of GreifswaldFelix-Hausdorff-Straße 4Greifswald17489Germany
- Center for Innovation Competence (ZIK) HIKE (Humoral Immune Reactions in Cardiovascular Diseases)University of GreifswaldGreifswaldFleischmannstraße 4217489Germany
| | - Sander Bekeschus
- Center for Innovation Competence (ZIK) plasmatisLeibniz Institute for Plasma Science and Technology (INP)Felix-Hausdorff-Straße 217489GreifswaldGermany
| | - Klaus‐Dieter Weltmann
- Center for Innovation Competence (ZIK) plasmatisLeibniz Institute for Plasma Science and Technology (INP)Felix-Hausdorff-Straße 217489GreifswaldGermany
| | - Thomas von Woedtke
- Center for Innovation Competence (ZIK) plasmatisLeibniz Institute for Plasma Science and Technology (INP)Felix-Hausdorff-Straße 217489GreifswaldGermany
- Institute for Hygiene and Environmental MedicineUniversity Medicine GreifswaldGreifswaldWalther-Rathenau-Straße 49 A17489Germany
| | - Kristian Wende
- Center for Innovation Competence (ZIK) plasmatisLeibniz Institute for Plasma Science and Technology (INP)Felix-Hausdorff-Straße 217489GreifswaldGermany
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6
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Pal S, Chattopadhyay A. Hydration Dynamics in Biological Membranes: Emerging Applications of Terahertz Spectroscopy. J Phys Chem Lett 2021; 12:9697-9709. [PMID: 34590862 DOI: 10.1021/acs.jpclett.1c02576] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Water drives the spontaneous self-assembly of lipids and proteins into quasi two-dimensional biological membranes that act as catalytic scaffolds for numerous processes central to life. However, the functional relevance of hydration in membrane biology is only beginning to be addressed, predominantly because of challenges associated with direct measurements of hydration microstructure and dynamics in a biological milieu. Our recent work on the novel interplay of membrane electrostatics and crowding in shaping membrane hydration dynamics utilizing terahertz (THz) spectroscopy represents an important step in this context. In this Perspective, we provide a glimpse into the ever-broadening functional landscape of hydration dynamics in biological membranes in the backdrop of the unique physical chemistry of water molecules. We further highlight the immense (and largely untapped) potential of the THz toolbox in addressing contemporary problems in membrane biology, while emphasizing the adaptability of the analytical framework reported recently by us to such studies.
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Affiliation(s)
- Sreetama Pal
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
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7
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Tryptophan, an Amino-Acid Endowed with Unique Properties and Its Many Roles in Membrane Proteins. CRYSTALS 2021. [DOI: 10.3390/cryst11091032] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Tryptophan is an aromatic amino acid with unique physico-chemical properties. It is often encountered in membrane proteins, especially at the level of the water/bilayer interface. It plays a role in membrane protein stabilization, anchoring and orientation in lipid bilayers. It has a hydrophobic character but can also engage in many types of interactions, such as π–cation or hydrogen bonds. In this review, we give an overview of the role of tryptophan in membrane proteins and a more detailed description of the underlying noncovalent interactions it can engage in with membrane partners.
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8
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Lee SY, Chen F, Lee TY. Tryptamine-functionalized magnetic nanoparticles for highly sensitive detection of Salmonella typhimurium. Analyst 2021; 146:2559-2566. [PMID: 33899066 DOI: 10.1039/d0an02458a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
There is significant demand for the development of rapid, sensitive, and specific methods for detecting bacterial pathogens in order to identify the causes of food poisoning. Nucleic acid amplification tests (NAATs) allow for the culture-free detection of bacterial pathogens and are not as labor intensive and time consuming as culture-based detection methods. However, suitable sample preparation methods must be developed for the realization of simple, rapid, and sensitive NAATs. To resolve this problem, we developed a new sample preparation method that integrates bacterial pathogen enrichment and DNA extraction. We engineered magnetic nanoparticles (MNPs) with a physicochemical probe (tryptamine) for single-tube sample preparation with minimal sample loss. The tryptamine-functionalized MNPs (Indole@MNPs) showed inherent hydrophobicity owing to the indole side chain and a change in their zeta potential with a decrease in the pH. Because of their physicochemical characteristics, the Indole@MNPs could adsorb bacterial pathogens, thus allowing sample enrichment and DNA binding and release through weak electrostatic interactions via pH control. We successfully detected Salmonella enterica serovar Typhimurium, a common cause of bacterial food poisoning, at a concentration of 10 CFU/10 mL in milk samples using quantitative PCR. Thus, the proposed method allows for the simple and sensitive detection of Salmonella typhimurium and can be used for nontyphoidal salmonella detection to ensure food safety.
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Affiliation(s)
- Seon-Yeong Lee
- Department of Technology Education, Chungnam National University, Daejeon, 34134, Republic of Korea
| | - Feixiong Chen
- Department of Convergence System Engineering and Department of Biomedical Engineering, Chungnam National University, Daejeon, 34134, Republic of Korea
| | - Tae Yoon Lee
- Department of Technology Education, Chungnam National University, Daejeon, 34134, Republic of Korea and Department of Convergence System Engineering and Department of Biomedical Engineering, Chungnam National University, Daejeon, 34134, Republic of Korea
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9
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10
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Joodaki F, Martin LM, Greenfield ML. Planarity and out-of-plane vibrational modes of tryptophan and tyrosine in biomolecular modeling. Phys Chem Chem Phys 2019; 21:23943-23965. [PMID: 31596287 DOI: 10.1039/c9cp04798k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Tryptophan and tyrosine are amino acids that play significant roles in the folding processes of proteins at water-membrane interfaces because of their amphipathic heteroaromatic rings. Employing appropriate heteroaromatic molecular structures is essential for obtaining accurate dynamics and predictive capabilities in molecular simulations of these amino acids. In this study, molecular dynamics simulations that applied the most recent version of the CHARMM36 force field were conducted on aqueous solutions of tryptophan and of tyrosine. Geometric analysis and dynamics quantified how aromatic rings deviated from planar structures and exhibited out-of-plane fluctuations. Radial distribution functions showed possible biological significance because the extent of ring planarity slightly affected local water concentrations near aromatic rings. Instantaneous all-atom normal mode analysis (NMA) and Fourier transformation of time autocorrelation functions of out-of-plane displacements were applied to study out-of-plane vibrations of atoms in these rings. The NMA started with minimum energy configurations and then averaged over fluctuations in aqueous solution. The frequencies and frequency patterns that were obtained for tryptophan and tyrosine with CHARMM36 differed from literature reports of Raman spectra, infrared spectra, and frequencies calculated using quantum mechanics, with some out-of-plane modes found at higher frequencies. Effects of imposing improper torsion potentials and changing torsion angle force constants were investigated for all atoms in the rings of tryptophan and tyrosine. Results show that these coarse force field variations only affect planarity and out-of-plane vibrations of atoms within the rings, and not other vibrations. Although increasing improper torsion force constants reduced deviations from aromatic ring planarity significantly, it increased out-of-plane mode frequencies. Reducing torsion angle force constants (with and without improper torsions) shifted modes to lower frequencies. A combination of decreasing most torsion angle force constants for ring atoms in both amino acids and including improper torsion forces attained frequencies and frequency patterns for out-of-plane normal modes that were more similar to the literature spectra. These force field variations decreased the extents of out-of-plane vibrations within the heteroaromatic rings of tryptophan, especially around the nitrogen atom in the ring, but not within the heteroaromatic ring of tyrosine. Conclusions were unaffected by the peptide endgroup, water, or simulation ensemble.
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Affiliation(s)
- Faramarz Joodaki
- Department of Chemical Engineering, University of Rhode Island, Kingston, Rhode Island 02881, USA.
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11
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Basma NS, Headen TF, Shaffer MSP, Skipper NT, Howard CA. Local Structure and Polar Order in Liquid N-Methyl-2-pyrrolidone (NMP). J Phys Chem B 2018; 122:8963-8971. [DOI: 10.1021/acs.jpcb.8b08020] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Nadir S. Basma
- Department of Chemistry, Imperial College London, South Kensington, London SW7 2AZ, U.K
- Department of Physics and Astronomy, University College London, London WC1E 6BT, U.K
| | - Thomas F. Headen
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, Oxfordshire, U.K
| | - Milo S. P. Shaffer
- Department of Chemistry, Imperial College London, South Kensington, London SW7 2AZ, U.K
| | - Neal T. Skipper
- Department of Physics and Astronomy, University College London, London WC1E 6BT, U.K
| | - Christopher A. Howard
- Department of Physics and Astronomy, University College London, London WC1E 6BT, U.K
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12
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Steinke N, Genina A, Gillams RJ, Lorenz CD, McLain SE. Proline and Water Stabilization of a Universal Two-Step Folding Mechanism for β-Turn Formation in Solution. J Am Chem Soc 2018; 140:7301-7312. [DOI: 10.1021/jacs.8b03643] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Nicola Steinke
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, U.K
| | - Anna Genina
- Department of Physics, King’s College London, London WC2R 2LS, U.K
| | | | | | - Sylvia E. McLain
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, U.K
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13
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Rhys NH, Al-Badri MA, Ziolek RM, Gillams RJ, Collins LE, Lawrence MJ, Lorenz CD, McLain SE. On the solvation of the phosphocholine headgroup in an aqueous propylene glycol solution. J Chem Phys 2018; 148:135102. [DOI: 10.1063/1.5024850] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Affiliation(s)
- Natasha H. Rhys
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
| | | | - Robert M. Ziolek
- Department of Physics, King’s College London, London WC2R 2LS, United Kingdom
| | - Richard J. Gillams
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
- Earth-Life Sciences Institute, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8550, Japan
| | - Louise E. Collins
- Department of Pharmaceutical Sciences, King’s College London, London SE1 9NH, United Kingdom
| | - M. Jayne Lawrence
- Division of Pharmacy and Optometry, University of Manchester, Manchester ML13 9PL, United Kingdom
| | - Christian D. Lorenz
- Department of Physics, King’s College London, London WC2R 2LS, United Kingdom
| | - Sylvia E. McLain
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
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14
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Mukherjee D, Ortiz Rodriguez LI, Hilaire MR, Troxler T, Gai F. 7-Cyanoindole fluorescence as a local hydration reporter: application to probe the microheterogeneity of nine water-organic binary mixtures. Phys Chem Chem Phys 2018; 20:2527-2535. [PMID: 29313858 DOI: 10.1039/c7cp07160d] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Considerable efforts have been devoted to the development of spectroscopic probes that are sensitive to water and can be used to monitor, for example, biological and chemical processes involving dehydration or hydration. Continuing this line of research, herein we show that 7-cyanoindole can serve as a sensitive fluorescence probe of hydration as its fluorescence properties, including intensity, peak wavelength and lifetime, depend on the amount of water in nine water-organic solvent mixtures. Our results indicate that 7-cyanoindole is not only able to reveal the underlying microheterogeneity of these binary solvent systems, but also offers distinct advantages. These include: (1) its fluorescence intensity increases more than ten times upon going from a hydrated to a dehydrated environment; (2) its peak wavelength shifts as much as 35 nm upon dehydration; (3) its single-exponential fluorescence decay lifetime increases from 2.0 ns in water to 8-16 ns in water-organic binary mixtures, making it viable to distinguish between differently hydrated environments via fluorescence lifetime measurements; and (4) its absorption spectrum is significantly red-shifted from that of indole, making selective excitation of its fluorescence possible in the presence of naturally occurring amino-acid fluorophores. Moreover, we find that for seven binary mixtures the fluorescence lifetimes of 7-cyanoindole measured at solvent compositions where maximum microheterogeneity occurs correlate linearly with the peak wavenumbers of its fluorescence spectra obtained in the respective pure organic solvents. This suggests that the microheterogeneities of these binary mixtures bear certain similarity, a phenomenon that warrants further investigation.
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Affiliation(s)
- Debopreeti Mukherjee
- Department of Chemistry University of Pennsylvania, 231 South 34th Street, Philadelphia, PA 19104, USA.
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15
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Ingram DJ, Headen TF, Skipper NT, Callear SK, Billing M, Sella A. Dihydrogen vs. hydrogen bonding in the solvation of ammonia borane by tetrahydrofuran and liquid ammonia. Phys Chem Chem Phys 2018; 20:12200-12209. [DOI: 10.1039/c7cp08220g] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The solvation structures of two systems rich in hydrogen and dihydrogen bonding interactions have been studied in detail experimentally through neutron diffraction with hydrogen/deuterium isotopic substitution.
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Affiliation(s)
- David J. Ingram
- Department of Physics & Astronomy
- University College London
- London
- UK
- Department of Chemistry
| | | | - Neal T. Skipper
- Department of Physics & Astronomy
- University College London
- London
- UK
- London Centre for Nanotechnology
| | | | | | - Andrea Sella
- Department of Chemistry
- University College London
- London
- UK
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16
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Graziano G. Comment on “On the positional and orientational order of water and methanol around indole: a study on the microscopic origin of solubility” Phys. Chem. Chem. Phys., 2016, 18, 23006. Phys Chem Chem Phys 2018; 20:2113-2115. [DOI: 10.1039/c7cp03698a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Indole solubility is larger in methanol than in water due to lower magnitude of the cavity creation work.
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Affiliation(s)
- Giuseppe Graziano
- Dipartimento di Scienze e Tecnologie
- Università del Sannio
- Via Port’Arsa 11
- 82100 Benevento
- Italy
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17
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Biondi B, Peggion C, De Zotti M, Pignaffo C, Dalzini A, Bortolus M, Oancea S, Hilma G, Bortolotti A, Stella L, Pedersen JZ, Syryamina VN, Tsvetkov YD, Dzuba SA, Toniolo C, Formaggio F. Conformational properties, membrane interaction, and antibacterial activity of the peptaibiotic chalciporin A: Multitechnique spectroscopic and biophysical investigations on the natural compound and labeled analogs. Biopolymers 2017; 110. [PMID: 29127716 DOI: 10.1002/bip.23083] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 10/06/2017] [Accepted: 10/15/2017] [Indexed: 02/28/2024]
Abstract
In this work, an extensive set of spectroscopic and biophysical techniques (including FT-IR absorption, CD, 2D-NMR, fluorescence, and CW/PELDOR EPR) was used to study the conformational preferences, membrane interaction, and bioactivity properties of the naturally occurring synthetic 14-mer peptaibiotic chalciporin A, characterized by a relatively low (≈20%), uncommon proportion of the strongly helicogenic Aib residue. In addition to the unlabeled peptide, we gained in-depth information from the study of two labeled analogs, characterized by one or two residues of the helicogenic, nitroxyl radical-containing TOAC. All three compounds were prepared using the SPPS methodology, which was carefully modified in the course of the syntheses of TOAC-labeled analogs in view of the poorly reactive α-amino function of this very bulky residue and the specific requirements of its free-radical side chain. Despite its potentially high flexibility, our results point to a predominant, partly amphiphilic, α-helical conformation for this peptaibiotic. Therefore, not surprisingly, we found an effective membrane affinity and a remarkable penetration propensity. However, chalciporin A exhibits a selectivity in its antibacterial activity not in agreement with that typical of the other members of this peptide class.
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Affiliation(s)
- Barbara Biondi
- Institute of Biomolecular, Chemistry, Padova Unit, CNR, Padova, 35131, Italy
| | - Cristina Peggion
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
| | - Marta De Zotti
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
| | - Chiara Pignaffo
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
| | - Annalisa Dalzini
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
| | - Marco Bortolus
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
| | - Simona Oancea
- Department of Agricultural Sciences and Food Engineering, "Lucian Blaga" University of Sibiu, Sibiu, 550012, Romania
| | - Geta Hilma
- Department of Medicine, "Lucian Blaga" University of Sibiu, Sibiu, 550012, Romania
| | - Annalisa Bortolotti
- Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, Rome, 00133, Italy
| | - Lorenzo Stella
- Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, Rome, 00133, Italy
| | - Jens Z Pedersen
- Department of Biology, University of Rome Tor Vergata, Rome, 00133, Italy
| | - Victoria N Syryamina
- Institute of Chemical Kinetics and Combustion, Novosibirsk, 630090, Russian Federation
| | - Yuri D Tsvetkov
- Institute of Chemical Kinetics and Combustion, Novosibirsk, 630090, Russian Federation
| | - Sergei A Dzuba
- Institute of Chemical Kinetics and Combustion, Novosibirsk, 630090, Russian Federation
| | - Claudio Toniolo
- Institute of Biomolecular, Chemistry, Padova Unit, CNR, Padova, 35131, Italy
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
| | - Fernando Formaggio
- Institute of Biomolecular, Chemistry, Padova Unit, CNR, Padova, 35131, Italy
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
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18
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Phenylalanine residues act as membrane anchors in the antimicrobial action of Aurein 1.2. Biointerphases 2017; 12:05G605. [PMID: 29078702 DOI: 10.1116/1.4995674] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Aurein 1.2 is a small cationic antimicrobial peptide, one of the shortest peptides that can exert antimicrobial activity at low micromolar concentrations. Aurein 1.2 is a surface acting peptide, following the "carpet" mechanism of thresholded membrane disruption. It is generally assumed that the activity of such cationic α-helical membrane disrupting peptides is charge driven. Here, the authors show that instead of charge interactions, aromatic phenylalanine residues of the Aurein 1.2 sequence facilitate the membrane binding. The activity of the wild type peptide was compared to mutants in which the Phe residues were substituted, singly and in tandem, with alanine. Measurements by quartz crystal microbalance, impedance spectroscopy, and dye leakage experiments demonstrated that single residue mutants retain a much-reduced activity whereas the deletion of both Phe residues prevents membrane disruption entirely. The single residue mutants exhibited an altered mechanism of action, permeabilizing but not dissolving the target membranes. These results offer a new design rule for membrane disrupting peptides with potential pharmacological applications.
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19
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Falcone N, Basak S, Dong B, Syed J, Ferranco A, Lough A, She Z, Kraatz HB. A Ferrocene-Tryptophan Conjugate: The Role of the Indolic Nitrogen in Supramolecular Assembly. Chempluschem 2017; 82:1282-1289. [DOI: 10.1002/cplu.201700407] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Indexed: 12/11/2022]
Affiliation(s)
- Natashya Falcone
- Department of Chemical Engineering and Applied Chemistry; University of Toronto; 200 College St Toronto ON M5S 3E5 Canada
- Department of Physical and Environmental Sciences; University of Toronto Scarborough; 1065 Military Trail Toronto ON M1C 1A4 Canada
| | - Shibaji Basak
- Department of Physical and Environmental Sciences; University of Toronto Scarborough; 1065 Military Trail Toronto ON M1C 1A4 Canada
| | - Bin Dong
- Department of Chemistry and Chemical Engineering, School of Chemistry and Biological Engineering; University of Science and Technology Beijing; Beijing 100083 P. R. China
| | - Jebriel Syed
- Department of Physical and Environmental Sciences; University of Toronto Scarborough; 1065 Military Trail Toronto ON M1C 1A4 Canada
| | - Annaleizle Ferranco
- Department of Physical and Environmental Sciences; University of Toronto Scarborough; 1065 Military Trail Toronto ON M1C 1A4 Canada
- Department of Chemistry; University of Toronto; 80 St. George Street Toronto ON M5S 3H6 Canada
| | - Alan Lough
- Department of Chemistry; University of Toronto; 80 St. George Street Toronto ON M5S 3H6 Canada
| | - Zhe She
- Department of Physical and Environmental Sciences; University of Toronto Scarborough; 1065 Military Trail Toronto ON M1C 1A4 Canada
| | - Heinz-Bernhard Kraatz
- Department of Chemical Engineering and Applied Chemistry; University of Toronto; 200 College St Toronto ON M5S 3E5 Canada
- Department of Physical and Environmental Sciences; University of Toronto Scarborough; 1065 Military Trail Toronto ON M1C 1A4 Canada
- Department of Chemistry; University of Toronto; 80 St. George Street Toronto ON M5S 3H6 Canada
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20
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Szala-Bilnik J, Falkowska M, Bowron DT, Hardacre C, Youngs TGA. The Structure of Ethylbenzene, Styrene and Phenylacetylene Determined by Total Neutron Scattering. Chemphyschem 2017; 18:2541-2548. [PMID: 28672104 PMCID: PMC5811833 DOI: 10.1002/cphc.201700393] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 06/30/2017] [Indexed: 11/10/2022]
Abstract
Organic solvents such as phenylacetylene, styrene and ethylbenzene are widely used in industrial processes, especially in the production of rubber or thermoplastics. Despite their important applications detailed knowledge about their structure is limited. In this paper the structures of these three aromatic solvents were investigated using neutron diffraction. The results show that many of their structural characteristics are similar, although the structure of phenylacetylene is more ordered and has a smaller solvation sphere than either ethylbenzene or styrene. Two regions within the first coordination sphere, in which the surrounding molecules show different preferable orientations with respect to the central molecule, were found for each liquid. Additionally, the localisation of the aliphatic chains reveals that they tend to favour closer interactions with each other than to the aromatic rings of the adjacent molecules.
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Affiliation(s)
- Joanna Szala-Bilnik
- School of Chemical Engineering and Analytical Science, The University of Manchester, Manchester, M13 9PL, UK.,STFC ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX, UK
| | - Marta Falkowska
- STFC ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX, UK.,School of Chemistry and Chemical Engineering, Queen's University Belfast, Belfast, BT9 5AG, UK
| | - Daniel T Bowron
- STFC ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX, UK
| | - Christopher Hardacre
- School of Chemical Engineering and Analytical Science, The University of Manchester, Manchester, M13 9PL, UK
| | - Tristan G A Youngs
- STFC ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX, UK
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21
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Duboué-Dijon E, Mason PE, Fischer HE, Jungwirth P. Changes in the hydration structure of imidazole upon protonation: Neutron scattering and molecular simulations. J Chem Phys 2017. [DOI: 10.1063/1.4982937] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Elise Duboué-Dijon
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nam. 2, 16610 Prague 6, Czech Republic
| | - Philip E. Mason
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nam. 2, 16610 Prague 6, Czech Republic
| | - Henry E. Fischer
- Institut Laue-Langevin, 71 Avenue des Martyrs, CS 20156, 38042 Grenoble Cedex 9, France
| | - Pavel Jungwirth
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nam. 2, 16610 Prague 6, Czech Republic
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22
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Maier JM, Li P, Vik EC, Yehl CJ, Strickland SMS, Shimizu KD. Measurement of Solvent OH−π Interactions Using a Molecular Balance. J Am Chem Soc 2017; 139:6550-6553. [DOI: 10.1021/jacs.7b02349] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Josef M. Maier
- Department
of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Ping Li
- Department
of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Erik C. Vik
- Department
of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Christopher J. Yehl
- Department
of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Sharon M. S. Strickland
- Department
of Biology, Chemistry, and Physics, Converse College, Spartanburg, South Carolina 29302, United States
| | - Ken D. Shimizu
- Department
of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
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23
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24
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Gillams RJ, Lorenz CD, McLain SE. Comparative atomic-scale hydration of the ceramide and phosphocholine headgroup in solution and bilayer environments. J Chem Phys 2017; 144:225101. [PMID: 27306021 DOI: 10.1063/1.4952444] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Previous studies have used neutron diffraction to elucidate the hydration of the ceramide and the phosphatidylcholine headgroup in solution. These solution studies provide bond-length resolution information on the system, but are limited to liquid samples. The work presented here investigates how the hydration of ceramide and phosphatidylcholine headgroups in a solution compares with that found in a lipid bilayer. This work shows that the hydration patterns seen in the solution samples provide valuable insight into the preferential location of hydrating water molecules in the bilayer. There are certain subtle differences in the distribution, which result from a combination of the lipid conformation and the lipid-lipid interactions within the bilayer environment. The lipid-lipid interactions in the bilayer will be dependent on the composition of the bilayer, whereas the restricted exploration of conformational space is likely to be applicable in all membrane environments. The generalized description of hydration gathered from the neutron diffraction studies thus provides good initial estimation for the hydration pattern, but this can be further refined for specific systems.
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Affiliation(s)
- Richard J Gillams
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
| | - Christian D Lorenz
- Department of Physics, King's College London, London WC2R 2LS, United Kingdom
| | - Sylvia E McLain
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
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25
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Romero-Romero S, Gomez Lagunas F, Balleza D. Side chain flexibility and coupling between the S4-S5 linker and the TRP domain in thermo-sensitive TRP channels: Insights from protein modeling. Proteins 2017; 85:630-646. [PMID: 28066924 DOI: 10.1002/prot.25243] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 12/01/2016] [Accepted: 01/03/2017] [Indexed: 11/11/2022]
Abstract
The transient receptor potential (TRP) superfamily is subdivided into several subfamilies on the basis of sequence similarity, which is highly heterogeneous but shows a molecular architecture that resembles the one present in members of the Kv channel superfamily. Because of this diversity, they produce a large variety of channels with different gating and permeability properties. Elucidation of these particular features necessarily requires comparative studies based on structural and functional data. The present study aims to compilate, analyze, and determine, in a coherent way, the relationship between intrinsic side-chain flexibility and the allosteric coupling in members of the TRPV, TRPM, and TRPC families. Based on the recently determined structures of TRPV1 and TRPV2, we have generated protein models for single subunits of TRPV5, TRPM8, and TRPC5 channels. With these models, we focused our attention on the apparently crucial role of the GP dipeptide at the center of the S4-S5 linker and discussed its role in the interaction with the TRP domain, specifically with the highly-conserved Trp during this coupling. Our analysis suggests an important role of the S4-S5L flexibility in the thermosensitivity, where heat-activated channels possess rigid S4-S5 linkers, whereas cold-activated channels have flexible ones. Finally, we also present evidence of the key interaction between the conserved Trp residue of the TRP box and of several residues in the S4-S5L, importantly the central Pro. Proteins 2017; 85:630-646. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Sergio Romero-Romero
- Facultad de Medicina, Departamento de Bioquímica, Universidad Nacional Autónoma de México, Mexico city, MEXICO
| | - Froylan Gomez Lagunas
- Facultad de Medicina, Departamento de Fisiología, Universidad Nacional Autónoma de México, Mexico city, MEXICO
| | - Daniel Balleza
- Facultad de Medicina, Departamento de Fisiología, Universidad Nacional Autónoma de México, Mexico city, MEXICO
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26
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Silva-Santisteban A, Steinke N, Johnston AJ, Ruiz GN, Carlos Pardo L, McLain SE. On the structure of prilocaine in aqueous and amphiphilic solutions. Phys Chem Chem Phys 2017; 19:12665-12673. [DOI: 10.1039/c7cp01723e] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The solvation of prilocaine has been investigated in pure water and in amphiphilic solutions using a combination of neutron diffraction and simulations.
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Affiliation(s)
- Alvaro Silva-Santisteban
- Department of Biochemistry
- University of Oxford
- Oxford OX1 3QU
- UK
- Departament de Física i Enginyeria Nuclear & Barcelona Research Center in Multiscale Science and Engineering
| | - Nicola Steinke
- Department of Biochemistry
- University of Oxford
- Oxford OX1 3QU
- UK
| | | | - Guadalupe N. Ruiz
- Departament de Física i Enginyeria Nuclear & Barcelona Research Center in Multiscale Science and Engineering
- Universitat Politècnica de Catalunya
- 08019 Barcelona
- Spain
| | - Luis Carlos Pardo
- Departament de Física i Enginyeria Nuclear & Barcelona Research Center in Multiscale Science and Engineering
- Universitat Politècnica de Catalunya
- 08019 Barcelona
- Spain
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27
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Maugeri L, Busch S, McLain SE, Pardo LC, Bruni F, Ricci MA. Structure-activity relationships in carbohydrates revealed by their hydration. Biochim Biophys Acta Gen Subj 2016; 1861:1486-1493. [PMID: 28011302 DOI: 10.1016/j.bbagen.2016.12.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 12/13/2016] [Accepted: 12/17/2016] [Indexed: 11/25/2022]
Abstract
One of the more intriguing aspects of carbohydrate chemistry is that despite having very similar molecular structures, sugars have very different properties. For instance, there is a sensible difference in sweet taste between glucose and trehalose, even though trehalose is a disaccharide that comprised two glucose units, suggesting a different ability of these two carbohydrates to bind to sweet receptors. Here we have looked at the hydration of specific sites and at the three-dimensional configuration of water molecules around three carbohydrates (glucose, cellobiose, and trehalose), combining neutron diffraction data with computer modelling. Results indicate that identical chemical groups can have radically different hydration patterns depending on their location on a given molecule. These differences can be linked with the specific activity of glucose, cellobiose, and trehalose as a sweet substance, as building block of cellulose fiber, and as a bioprotective agent, respectively. This article is part of a Special Issue entitled "Recent Advances in Bionanomaterials" Guest Editors: Dr. Marie-Louise Saboungi and Dr. Samuel D. Bader.
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Affiliation(s)
- Laura Maugeri
- Dipartimento di Scienze, Università degli Studi Roma Tre, Via della Vasca Navale 84, Roma 00146, Italy
| | - Sebastian Busch
- German Engineering Materials Science Centre (GEMS) at Heinz Maier-Leibnitz Zentrum (MLZ), Helmholtz-Zentrum Geesthacht GmbH, Lichtenbergstr. Garching bei München 1 85747, Germany
| | - Sylvia E McLain
- Department of Biochemistry, University of Oxford, South Park Road, Oxford, Oxfordshire OX1 3QU, UK
| | - Luis Carlos Pardo
- Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya Barcelona 08028, Catalonia, Spain
| | - Fabio Bruni
- Dipartimento di Scienze, Università degli Studi Roma Tre, Via della Vasca Navale 84, Roma 00146, Italy
| | - Maria Antonietta Ricci
- Dipartimento di Scienze, Università degli Studi Roma Tre, Via della Vasca Navale 84, Roma 00146, Italy.
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28
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Lenton S, Walsh DL, Rhys NH, Soper AK, Dougan L. Structural evidence for solvent-stabilisation by aspartic acid as a mechanism for halophilic protein stability in high salt concentrations. Phys Chem Chem Phys 2016; 18:18054-62. [PMID: 27327567 DOI: 10.1039/c6cp02684b] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Halophilic organisms have adapted to survive in high salt environments, where mesophilic organisms would perish. One of the biggest challenges faced by halophilic proteins is the ability to maintain both the structure and function at molar concentrations of salt. A distinct adaptation of halophilic proteins, compared to mesophilic homologues, is the abundance of aspartic acid on the protein surface. Mutagenesis and crystallographic studies of halophilic proteins suggest an important role for solvent interactions with the surface aspartic acid residues. This interaction, between the regions of the acidic protein surface and the solvent, is thought to maintain a hydration layer around the protein at molar salt concentrations thereby allowing halophilic proteins to retain their functional state. Here we present neutron diffraction data of the monomeric zwitterionic form of aspartic acid solutions at physiological pH in 0.25 M and 2.5 M concentration of potassium chloride, to mimic mesophilic and halophilic-like environmental conditions. We have used isotopic substitution in combination with empirical potential structure refinement to extract atomic-scale information from the data. Our study provides structural insights that support the hypothesis that carboxyl groups on acidic residues bind water more tightly under high salt conditions, in support of the residue-ion interaction model of halophilic protein stabilisation. Furthermore our data show that in the presence of high salt the self-association between the zwitterionic form of aspartic acid molecules is reduced, suggesting a possible mechanism through which protein aggregation is prevented.
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Affiliation(s)
- Samuel Lenton
- School of Physics and Astronomy, University of Leeds, Leeds, UK.
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29
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Zhang W, Markiewicz BN, Doerksen RS, Smith AB, Gai F. C≡N stretching vibration of 5-cyanotryptophan as an infrared probe of protein local environment: what determines its frequency? Phys Chem Chem Phys 2016; 18:7027-34. [PMID: 26343769 PMCID: PMC4775302 DOI: 10.1039/c5cp04413h] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Recently it has been suggested that the C≡N stretching vibration of a tryptophan analog, 5-cyanotryptophan, could be used as an infrared probe of the local environment, especially the hydration status, of tryptophan residues in proteins. However, the factors that influence the frequency of this vibrational mode are not understood. To determine these factors, herein we carried out linear and nonlinear infrared measurements on the C≡N stretching vibration of the sidechain of 5-cyanotryptophan, 3-methyl-5-cyanoindole, in a series of protic and aprotic solvents. We found that while the C≡N stretching frequencies obtained in these solvents do not correlate well with any individual Kamlet-Taft solvent parameter, i.e., π* (polarizability), β (hydrogen bond accepting ability), and α (hydrogen bond donating ability), they do however, collapse on a straight line when plotted against σ = π* + β - α. This linear relationship provides a firm indication that both specific interactions, i.e., hydrogen-bonding interactions with the C≡N (through α) and indole N-H (through β) groups, and non-specific interactions with the molecule (through π*) work together to determine the C≡N stretching frequency, thus laying a quantitative framework for applying 5-cyanotryptophan to investigate the microscopic environment of proteins in a site-specific manner. Furthermore, two-dimensional and pump-probe infrared measurements revealed that a significant portion (∼31%) of the ground state bleach signal has a decay time constant of ∼12.3 ps, due to an additional vibrational relaxation channel, making it possible to use 5-cyanotryptophan to probe dynamics occurring on a timescale on the order of tens of picoseconds.
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Affiliation(s)
- Wenkai Zhang
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA. and The Ultrafast Optical Processes Laboratory, University of Pennsylvania, Philadelphia, PA 19104, USA
| | | | - Rosalie S Doerksen
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Amos B Smith
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Feng Gai
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA. and The Ultrafast Optical Processes Laboratory, University of Pennsylvania, Philadelphia, PA 19104, USA
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30
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Markiewicz BN, Mukherjee D, Troxler T, Gai F. Utility of 5-Cyanotryptophan Fluorescence as a Sensitive Probe of Protein Hydration. J Phys Chem B 2016; 120:936-44. [PMID: 26783936 DOI: 10.1021/acs.jpcb.5b12233] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Tryptophan (Trp) fluorescence has been widely used to interrogate the structure, dynamics, and function of proteins. In particular, it provides a convenient and site-specific means to probe a protein's hydration status and dynamics. Herein, we show that a tryptophan analogue, 5-cyanotryptophan (TrpCN), can also be used for this purpose, but with the benefit of enhanced sensitivity to hydration. This conclusion is reached based on measurements of the static and time-resolved fluorescence properties of 5-cyanoindole, TrpCN, and TrpCN-containing peptides in different solvents, which indicate that upon dehydration the fluorescence quantum yield (QY) and lifetime (τF) of TrpCN undergo a much greater change in comparison to those of Trp. For example, in H2O the QY of TrpCN is less than 0.01, which increases to 0.11 in 1,4-dioxane. Consistently, the fluorescence decay kinetics of TrpCN in H2O are dominated by a 0.4 ns component, whereas in 1,4-dioxane the kinetics are dominated by a 6.0 ns component. The versatile utility of TrpCN as a sensitive fluorescence reporter is further demonstrated in three applications, where we used it (1) to probe the solvent property of a binary mixture consisting of dimethyl sulfoxide and H2O, (2) to monitor the binding interaction of an antimicrobial peptide with lipid membranes, and (3) to differentiate two differently hydrated environments in a folded protein.
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Affiliation(s)
- Beatrice N Markiewicz
- Department of Chemistry and ‡The Ultrafast Optical Processes Laboratory, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
| | - Debopreeti Mukherjee
- Department of Chemistry and ‡The Ultrafast Optical Processes Laboratory, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
| | - Thomas Troxler
- Department of Chemistry and ‡The Ultrafast Optical Processes Laboratory, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
| | - Feng Gai
- Department of Chemistry and ‡The Ultrafast Optical Processes Laboratory, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
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31
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Steinke N, Gillams RJ, Pardo LC, Lorenz CD, McLain SE. Atomic scale insights into urea–peptide interactions in solution. Phys Chem Chem Phys 2016; 18:3862-70. [DOI: 10.1039/c5cp06646h] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Investigations on the β-turn forming peptide, GPG, suggest that urea denatures proteins by replacing water molecules and subsequently weakening the peptide bonds as a possible mechanism of protein denaturation by urea.
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Affiliation(s)
- Nicola Steinke
- Department of Biochemistry
- University of Oxford
- Oxford OX1 3QU
- UK
| | | | - Luis Carlos Pardo
- Departament de Física i Enginyeria Nuclear
- Escola Tècnica Superior d'Enginyeria Industrial de Barcelona (ETSEIB)
- Universitat Politècnica de Catalunya
- 08028 Barcelona
- Catalonia, Spain
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32
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Sridhar A, Johnston AJ, Varathan L, McLain SE, Biggin PC. The solvation structure of alprazolam. Phys Chem Chem Phys 2016; 18:22416-25. [DOI: 10.1039/c6cp02645a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Alprazolam is a benzodiazepine that is commonly prescribed for the treatment of anxiety and other related disorders.
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33
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Henao A, Johnston AJ, Guàrdia E, McLain SE, Pardo LC. On the positional and orientational order of water and methanol around indole: a study on the microscopic origin of solubility. Phys Chem Chem Phys 2016; 18:23006-16. [DOI: 10.1039/c6cp04183c] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The increase in solubility for indole in methanol water solutions relative to pure water is a result methanol −OH–π interactions. In addition, excess entropy calculations suggest that this process is enthalpically rather than entropically driven.
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Affiliation(s)
- Andres Henao
- Grup de Caracterització de Materials
- Departament de Física
- ETSEIB
- Universitat Politècnica de Catalunya
- E-08028 Barcelona
| | | | - Elvira Guàrdia
- Grup de Simulació per Ordinador en Matèria Condensada
- Departament de Física
- B4-B5 Campus Nord
- Universitat Politècnica de Catalunya
- E-08034 Barcelona
| | | | - Luis Carlos Pardo
- Grup de Caracterització de Materials
- Departament de Física
- ETSEIB
- Universitat Politècnica de Catalunya
- E-08028 Barcelona
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34
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Johnston AJ, Busch S, Pardo LC, Callear SK, Biggin PC, McLain SE. On the atomic structure of cocaine in solution. Phys Chem Chem Phys 2016; 18:991-9. [DOI: 10.1039/c5cp06090g] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A combination of neutron diffraction and computation has been used to investigate the atomic scale structure of cocaine in aqueous solutions.
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Affiliation(s)
| | - Sebastian Busch
- German Engineering Materials Science Centre (GEMS) at Heinz Maier-Leibnitz Zentrum (MLZ)
- Helmholtz-Zentrum Geesthacht GmbH
- 85747 Garching bei München
- Germany
| | - Luis Carlos Pardo
- Departament de Física i Enginyeria Nuclear
- Escola Tècnica Superior d'Enginyeria Industrial de Barcelona (ETSEIB)
- Universitat Politècnica de Catalunya
- 08028 Barcelona
- Spain
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