1
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Feng RR, Wang M, Zhang W, Gai F. Unnatural Amino Acids for Biological Spectroscopy and Microscopy. Chem Rev 2024; 124:6501-6542. [PMID: 38722769 DOI: 10.1021/acs.chemrev.3c00944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/23/2024]
Abstract
Due to advances in methods for site-specific incorporation of unnatural amino acids (UAAs) into proteins, a large number of UAAs with tailored chemical and/or physical properties have been developed and used in a wide array of biological applications. In particular, UAAs with specific spectroscopic characteristics can be used as external reporters to produce additional signals, hence increasing the information content obtainable in protein spectroscopic and/or imaging measurements. In this Review, we summarize the progress in the past two decades in the development of such UAAs and their applications in biological spectroscopy and microscopy, with a focus on UAAs that can be used as site-specific vibrational, fluorescence, electron paramagnetic resonance (EPR), or nuclear magnetic resonance (NMR) probes. Wherever applicable, we also discuss future directions.
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Affiliation(s)
- Ran-Ran Feng
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Manxi Wang
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Wenkai Zhang
- Department of Physics and Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China
| | - Feng Gai
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
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2
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Khan S, Siraj S, Shahid M, Haque MM, Islam A. Osmolytes: Wonder molecules to combat protein misfolding against stress conditions. Int J Biol Macromol 2023; 234:123662. [PMID: 36796566 DOI: 10.1016/j.ijbiomac.2023.123662] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 02/03/2023] [Accepted: 02/09/2023] [Indexed: 02/17/2023]
Abstract
The proper functioning of any protein depends on its three dimensional conformation which is achieved by the accurate folding mechanism. Keeping away from the exposed stress conditions leads to cooperative unfolding and sometimes partial folding, forming the structures like protofibrils, fibrils, aggregates, oligomers, etc. leading to several neurodegenerative diseases like Parkinson's disease, Alzheimer's, Cystic fibrosis, Huntington, Marfan syndrome, and also cancers in some cases, too. Hydration of proteins is necessary, which may be achieved by the presence of organic solutes called osmolytes within the cell. Osmolytes belong to different classes in different organisms and play their role by preferential exclusion of osmolytes and preferential hydration of water molecules and achieves the osmotic balance in the cell otherwise it may cause problems like cellular infection, cell shrinkage leading to apoptosis and cell swelling which is also the major injury to the cell. Osmolyte interacts with protein, nucleic acids, intrinsically disordered proteins by non-covalent forces. Stabilizing osmolytes increases the Gibbs free energy of the unfolded protein and decreases that of folded protein and vice versa with denaturants (urea and guanidinium hydrochloride). The efficacy of each osmolyte with the protein is determined by the calculation of m value which reflects its efficiency with protein. Hence osmolytes can be therapeutically considered and used in drugs.
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Affiliation(s)
- Sobia Khan
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India
| | - Seerat Siraj
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India; Department of Biotechnology, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India
| | - Mohammad Shahid
- Department of Basic Medical Sciences, College of Medicine, Prince Sattam bin Abdulaziz University, P.O. Box: 173, Al Kharj, Saudi Arabia
| | | | - Asimul Islam
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025, India.
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3
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Negi I, Jangra R, Gharu A, Trant JF, Sharma P. Guanidinium–amino acid hydrogen-bonding interactions in protein crystal structures: implications for guanidinium-induced protein denaturation. Phys Chem Chem Phys 2023; 25:857-869. [DOI: 10.1039/d2cp04943k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Structural analysis of guanidinium–amino acid interaction pairs in protein crystal structures is coupled with an effective scheme for classifying the optimized pairs, to gain understanding of the guanidinium:protein hydrogen bonding modes.
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Affiliation(s)
- Indu Negi
- Computational Biochemistry Laboratory, Department of Chemistry and Centre for Advanced Studies in Chemistry, Panjab University, Chandigarh, 160014, India
| | - Raman Jangra
- Computational Biochemistry Laboratory, Department of Chemistry and Centre for Advanced Studies in Chemistry, Panjab University, Chandigarh, 160014, India
| | - Amit Gharu
- Computational Biochemistry Laboratory, Department of Chemistry and Centre for Advanced Studies in Chemistry, Panjab University, Chandigarh, 160014, India
| | - John F. Trant
- Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Ave. Windsor ON, N9B 3P4, Canada
- Binary Star Research Services, LaSalle, ON, N9J 3 X 8, Canada
| | - Purshotam Sharma
- Computational Biochemistry Laboratory, Department of Chemistry and Centre for Advanced Studies in Chemistry, Panjab University, Chandigarh, 160014, India
- Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Ave. Windsor ON, N9B 3P4, Canada
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4
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Ajayi S, Asakereh I, Rezasoltani H, Davidson D, Khajehpour M. Does Urea Preferentially Interact with Amide Moieties or Nonpolar Sidechains? A Question Answered Through a Judicious Selection of Model Systems. Chemphyschem 2022; 24:e202200731. [PMID: 36478636 DOI: 10.1002/cphc.202200731] [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: 10/04/2022] [Revised: 12/02/2022] [Accepted: 12/06/2022] [Indexed: 12/13/2022]
Abstract
The transfer model suggests that urea unfolds proteins mainly by increasing the solubility of the amide backbone, probably through urea-induced increase in hydrogen bonding. Other studies suggest that urea addition increases the magnitude of solvent-solute van der Waals interactions, which increases the solubility of nonpolar sidechains. More recent analyses hypothesize that urea has a similar effect in increasing the solubility of backbone and sidechain groups. In this work, we compare the effects of urea addition on the solvation of amides and alkyl groups. At first, we study the effects of urea addition upon solvent hydrogen bonding acidity and basicity through the perturbation in the fluorescence spectrum of probes 1-AN and 1-DMAN. Our results demonstrate that the solvent's hydrogen bonding properties are minimally affected by urea addition. Subsequently, we show that urea addition does not perturb the intra-molecular hydrogen bonding in salicylic acid significantly. Finally, we investigate how urea preferentially interacts with amide and alkyl groups moieties in water by comparing the effects of urea addition upon the solubility of acetaminophen and 4-tertbutylphenol. We show that urea affects amide and t-butyl solubility (lowers the transfer free energy of both amide (backbone) and alkyl (sidechain) groups) in a similar fashion. In other words, preferential interaction of urea with both moieties contributes to protein denaturation.
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Affiliation(s)
- Simisola Ajayi
- Department of Chemistry, the, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada
| | - Iman Asakereh
- Department of Chemistry, the, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada
| | - Hanieh Rezasoltani
- Department of Chemistry, the, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada
| | - David Davidson
- Department of Chemistry, the, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada
| | - Mazdak Khajehpour
- Department of Chemistry, the, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada
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5
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Monhemi H, Hoang HN, Standley DM, Matsuda T, Housaindokht MR. The protein-stabilizing effects of TMAO in aqueous and non-aqueous conditions. Phys Chem Chem Phys 2022; 24:21178-21187. [PMID: 36039911 DOI: 10.1039/d2cp01279k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present a new water-dependent molecular mechanism for the widely-used protein stabilizing osmolyte, trimethylamine N-oxide (TMAO), whose mode of action has remained controversial. Classical interpretations, such as osmolyte exclusion from the vicinity of protein, cannot adequately explain the behavior of this osmolyte and were challenged by recent data showing the direct interactions of TMAO with proteins, mainly via hydrophobic binding. Solvent effect theories also fail to propose a straightforward mechanism. To explore the role of water and the hydrophobic association, we disabled osmolyte-protein hydrophobic interactions by replacing water with hexane and using lipase enzyme as an anhydrous-stable protein. Biocatalysis experiments showed that under this non-aqueous condition, TMAO does not act as a stabilizer, but strongly deactivates the enzyme. Molecular dynamics (MD) simulations reveal that TMAO accumulates near the enzyme and makes many hydrogen bonds with it, like denaturing osmolytes. Some TMAO molecules even reach the active site and interact strongly with the catalystic traid. In aqueous solvent, the enzyme functions well: the extent of TMAO interactions is reduced and can be divided into both polar and non-polar terms. Structural analysis shows that in water, some TMAO molecules bind to the enzyme surface like a surfactant. We show that these interactions limit water-protein hydrogen bonds and unfavorable water-hydrophobic surface contacts. Moreover, a more hydrophobic environment is formed in the solvation layer, which reduces water dynamics and subsequently, rigidifies the backbone in aqueous solution. We show that osmolyte amphiphilicity and protein surface heterogeneity can address the weaknesses of exclusion and solvent effect theories about the TMAO mechanism.
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Affiliation(s)
- Hassan Monhemi
- Department of Chemistry, University of Neyshabur, Neyshabur, Iran. .,Research and Technology Center of Biomolecules, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Hai Nam Hoang
- Department of Food Technology, Faculty of Chemical Engineering, Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet Street, District 10, Ho Chi Minh City, Vietnam.,Vietnam National University Ho Chi Minh City, Linh Trung Ward, Thu Duc District, Ho Chi Minh City, Vietnam
| | - Daron M Standley
- Laboratory of Systems Immunology, WPI Immunology Frontier Research Center Osaka University, Osaka 565-0871, Japan
| | - Tomoko Matsuda
- School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8501, Japan
| | - Mohammad Reza Housaindokht
- Research and Technology Center of Biomolecules, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran
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6
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Gilani AG, Haghighat AG. A comparative photophysical study of molecular associative of structurally similar phenothiazine dyes in aqueous solutions of caffeine. J Mol Struct 2022. [DOI: 10.1016/j.molstruc.2022.133861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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7
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Hydration of Simple Model Peptides in Aqueous Osmolyte Solutions. Int J Mol Sci 2021; 22:ijms22179350. [PMID: 34502252 PMCID: PMC8431001 DOI: 10.3390/ijms22179350] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 08/13/2021] [Accepted: 08/24/2021] [Indexed: 12/13/2022] Open
Abstract
The biology and chemistry of proteins and peptides are inextricably linked with water as the solvent. The reason for the high stability of some proteins or uncontrolled aggregation of others may be hidden in the properties of their hydration water. In this study, we investigated the effect of stabilizing osmolyte–TMAO (trimethylamine N-oxide) and destabilizing osmolyte–urea on hydration shells of two short peptides, NAGMA (N-acetyl-glycine-methylamide) and diglycine, by means of FTIR spectroscopy and molecular dynamics simulations. We isolated the spectroscopic share of water molecules that are simultaneously under the influence of peptide and osmolyte and determined the structural and energetic properties of these water molecules. Our experimental and computational results revealed that the changes in the structure of water around peptides, caused by the presence of stabilizing or destabilizing osmolyte, are significantly different for both NAGMA and diglycine. The main factor determining the influence of osmolytes on peptides is the structural-energetic similarity of their hydration spheres. We showed that the chosen peptides can serve as models for various fragments of the protein surface: NAGMA for the protein backbone and diglycine for the protein surface with polar side chains.
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8
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Sahle CJ, Schroer MA, Niskanen J, Elbers M, Jeffries CM, Sternemann C. Hydration in aqueous osmolyte solutions: the case of TMAO and urea. Phys Chem Chem Phys 2020; 22:11614-11624. [DOI: 10.1039/c9cp06785j] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
X-ray Raman scattering spectroscopy and first principles simulations reveal details of the hydration and hydrogen-bond topology of trimethylamine N-oxide (TMAO) and urea in aqueous solutions.
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Affiliation(s)
| | - Martin A. Schroer
- European Molecular Biology Laboratory (EMBL)
- Hamburg Outstation c/o DESY
- Hamburg 22607
- Germany
| | - Johannes Niskanen
- Department of Physics and Astronomy
- University of Turku
- FI-20014 Turun Yliopisto
- Finland
| | - Mirko Elbers
- Fakultät Physik/DELTA
- Technische Universität Dortmund
- 44221 Dortmund
- Germany
| | - Cy M. Jeffries
- European Molecular Biology Laboratory (EMBL)
- Hamburg Outstation c/o DESY
- Hamburg 22607
- Germany
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9
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Jahan I, Nayeem SM. Effect of Osmolytes on Conformational Behavior of Intrinsically Disordered Protein α-Synuclein. Biophys J 2019; 117:1922-1934. [PMID: 31699336 DOI: 10.1016/j.bpj.2019.09.046] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 09/21/2019] [Accepted: 09/30/2019] [Indexed: 11/20/2022] Open
Abstract
α-Synuclein is an intrinsically disordered protein whose function in a healthy brain is poorly understood. It is genetically and neuropathologically linked to Parkinson's disease (PD). PD is manifested after the accumulation of plaques of α-synuclein aggregates in the brain cells. Aggregates of α-synuclein are very toxic and lead to the disruption of cellular homeostasis and neuronal death. α-Synuclein can also contribute to disease propagation as it may exert noxious effects on neighboring cells. Understanding the mechanism of α-synuclein aggregation will facilitate the problem of dealing with neurodegenerative diseases in general and that of PD in particular. Here, we have used molecular dynamics simulations to investigate the behavior of α-synuclein at various temperatures and in different concentrations of urea and trimethyl amine oxide. The residue region from 61 to 95 of α-synuclein is experimentally known as amyloidogenic. In our study, we have identified some other regions, which also have the propensity to form an aggregate besides this known sequence. Urea being a denaturant interacts more with these regions of α-synuclein through hydrogen bond formation and inhibits the β-sheet formation, whereas trimethyl amine oxide itself does not interact much with the protein and stabilizes the protein by preferentially distributing water molecules on the surface of the protein.
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Affiliation(s)
- Ishrat Jahan
- Department of Chemistry, Aligarh Muslim University, Aligarh, Uttar Pradesh, India
| | - Shahid M Nayeem
- Department of Chemistry, Aligarh Muslim University, Aligarh, Uttar Pradesh, India.
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10
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Raskar T, Koh CY, Niebling S, Kini RM, Hosur MV. X-ray crystallographic analysis of time-dependent binding of guanidine hydrochloride to HEWL: First steps during protein unfolding. Int J Biol Macromol 2018; 122:903-913. [PMID: 30412756 DOI: 10.1016/j.ijbiomac.2018.11.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 10/24/2018] [Accepted: 11/05/2018] [Indexed: 01/02/2023]
Abstract
Time-dependent binding of guanidine hydrochloride (GuHCl) to hen egg-white lysozyme (HEWL), and effects of this binding on the protein structure have been investigated by solving X-ray structures of crystalline complexes. The complexes have been prepared by soaking, for different periods of time, native lysozyme crystals in solutions containing 2.5M GuHCl. In the refined structures, the number of water molecules in the protein's first solvent shell has progressively decreased from 152 to 115, showing protein's preference for guanidinium over water. Guanidinium ions preferentially hydrogen bond with the backbone carbonyl oxygen atoms. In their van der Waals interactions, they do not show any preference for apolar residues. Guanidinium ions have replaced water molecules that form cages around exposed hydrophobic residues. Guanidinium binding has decreased the average length of water-water hydrogen bond by 0.1Å. The hydrogen bonds between main chain atoms have been weakened by GuHCl, and this may be the reason for increased potency of GuHCl compared to urea. Guanidinium binding destabilizes the β-domain by causing loss of hydrogen bonds involving Asn 59 side chain. Interestingly, this loss is almost identical to that observed in structures of amyloidogenic variants of human lysozyme. Compounds preventing this loss could be anti-amyloidogenic.
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Affiliation(s)
- Tushar Raskar
- Ultrafast Molecular Dynamics Group, Centre for Hybrid Nanostructures (ChyN), University of Hamburg, Germany
| | - Cho Yeow Koh
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Stephan Niebling
- Ultrafast Molecular Dynamics Group, Centre for Hybrid Nanostructures (ChyN), University of Hamburg, Germany
| | - R M Kini
- Department of Biological Sciences, National University of Singapore, Singapore
| | - M V Hosur
- National Institute of Advanced Studies, IISc campus, Bengaluru 560012, India.
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11
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Xie WJ, Cha S, Ohto T, Mizukami W, Mao Y, Wagner M, Bonn M, Hunger J, Nagata Y. Large Hydrogen-Bond Mismatch between TMAO and Urea Promotes Their Hydrophobic Association. Chem 2018. [DOI: 10.1016/j.chempr.2018.08.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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12
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Ding B, Yang L, Mukherjee D, Chen J, Gao Y, Gai F. Microscopic Insight into the Protein Denaturation Action of Urea and Its Methyl Derivatives. J Phys Chem Lett 2018; 9:2933-2940. [PMID: 29767523 DOI: 10.1021/acs.jpclett.8b00960] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We employ site-specific, linear and nonlinear infrared spectroscopic techniques as well as fluorescence spectroscopy and molecular dynamics simulations to investigate the binding interactions of urea and three of its derivatives, methylurea, 1,3-dimethylurea, and tetramethylurea, with protein aromatic and polar side chains. We find that (1) urea methylation leads to preferential interactions between the cosolvent molecules and aromatic side chains with an affinity that increases with the number of methyl groups; (2) interactions with tetramethylurea cause significant dehydration of aromatic side chains and the effect is most pronounced for tryptophan; and (3) while neither urea nor tetramethylurea shows preferential accumulation around a polar side chain, the number of hydrogen-bond donors around this side chain is significantly decreased in the presence of tetramethylurea. Taken together, our findings suggest that these urea derivatives, especially tetramethylurea, can effectively disrupt hydrophobic interactions in proteins. Additionally, tetramethylurea can promote intramolecular hydrogen-bond formation and hence induce α-helix folding in peptides, as observed.
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Affiliation(s)
| | - Lijiang Yang
- College of Chemistry and Molecular Engineering , Peking University , Beijing 100871 , China
| | | | | | - Yiqin Gao
- College of Chemistry and Molecular Engineering , Peking University , Beijing 100871 , China
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13
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Chen HC, Liu YC. Creating functional water by treating excited gold nanoparticles for the applications of green chemistry, energy and medicine: A review. J IND ENG CHEM 2018. [DOI: 10.1016/j.jiec.2017.09.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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14
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Martin JP, Fetto NR, Tucker MJ. Comparison of biological chromophores: photophysical properties of cyanophenylalanine derivatives. Phys Chem Chem Phys 2018; 18:20750-7. [PMID: 27412819 DOI: 10.1039/c6cp04154j] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Within this work, the family of cyanophenylalanine spectroscopic reporters is extended by showing the ortho and meta derivatives have intrinsic photophysical properties that are useful for studies of protein structure and dynamics. The molar absorptivities of 2-cyanophenylalanine and 3-cyanophenylalanine are shown to be comparable to that of 4-cyanophenylalanine with similar spectral features in their absorbance and emission profiles, demonstrating that these probes can be utilized interchangeably. The fluorescence quantum yields are also on the same scale as commonly used fluorophores in peptides and proteins, tyrosine and tryptophan. These new cyano-fluorophores can be paired with either 4-cyanophenylalanine or tryptophan to capture distances in peptide structure through Förster resonance energy transfer. Additionally, the spectroscopic properties of these chromophores can report the local solvent environment via changes in fluorescence emission intensity as a result of hydrogen bonding and/or hydration. A decrease in the quantum yield is also observed in basic environments due to photoinduced electron transfer from a deprotonated amine in the free PheCN species and at the N-terminus of a short peptide, providing an avenue to detect pH in biological systems. Our results show the potential of these probes, 2-cyanophenylalanine and 3-cyanophenylalanine, to be incorporated into a single peptide chain, either individually or in tandem with 4-cyanophenylalanine, tryptophan, or tyrosine, in order to obtain information about peptide structure and dynamics.
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Affiliation(s)
- Joshua P Martin
- Department of Chemistry, University of Nevada, Reno, 89557, USA.
| | - Natalie R Fetto
- Department of Chemistry, University of Nevada, Reno, 89557, USA.
| | - Matthew J Tucker
- Department of Chemistry, University of Nevada, Reno, 89557, USA.
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15
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Trimethylamine N-oxide stabilizes proteins via a distinct mechanism compared with betaine and glycine. Proc Natl Acad Sci U S A 2017; 114:2479-2484. [PMID: 28228526 DOI: 10.1073/pnas.1614609114] [Citation(s) in RCA: 123] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We report experimental and computational studies investigating the effects of three osmolytes, trimethylamine N-oxide (TMAO), betaine, and glycine, on the hydrophobic collapse of an elastin-like polypeptide (ELP). All three osmolytes stabilize collapsed conformations of the ELP and reduce the lower critical solution temperature (LSCT) linearly with osmolyte concentration. As expected from conventional preferential solvation arguments, betaine and glycine both increase the surface tension at the air-water interface. TMAO, however, reduces the surface tension. Atomically detailed molecular dynamics (MD) simulations suggest that TMAO also slightly accumulates at the polymer-water interface, whereas glycine and betaine are strongly depleted. To investigate alternative mechanisms for osmolyte effects, we performed FTIR experiments that characterized the impact of each cosolvent on the bulk water structure. These experiments showed that TMAO red-shifts the OH stretch of the IR spectrum via a mechanism that was very sensitive to the protonation state of the NO moiety. Glycine also caused a red shift in the OH stretch region, whereas betaine minimally impacted this region. Thus, the effects of osmolytes on the OH spectrum appear uncorrelated with their effects upon hydrophobic collapse. Similarly, MD simulations suggested that TMAO disrupts the water structure to the least extent, whereas glycine exerts the greatest influence on the water structure. These results suggest that TMAO stabilizes collapsed conformations via a mechanism that is distinct from glycine and betaine. In particular, we propose that TMAO stabilizes proteins by acting as a surfactant for the heterogeneous surfaces of folded proteins.
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16
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Adhikary R, Zimmermann J, Romesberg FE. Transparent Window Vibrational Probes for the Characterization of Proteins With High Structural and Temporal Resolution. Chem Rev 2017; 117:1927-1969. [DOI: 10.1021/acs.chemrev.6b00625] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Ramkrishna Adhikary
- Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037, United States
| | - Jörg Zimmermann
- Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037, United States
| | - Floyd E. Romesberg
- Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037, United States
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17
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Do guanidinium and tetrapropylammonium ions specifically interact with aromatic amino acid side chains? Proc Natl Acad Sci U S A 2017; 114:1003-1008. [PMID: 28096375 DOI: 10.1073/pnas.1618071114] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Many ions are known to affect the activity, stability, and structural integrity of proteins. Although this effect can be generally attributed to ion-induced changes in forces that govern protein folding, delineating the underlying mechanism of action still remains challenging because it requires assessment of all relevant interactions, such as ion-protein, ion-water, and ion-ion interactions. Herein, we use two unnatural aromatic amino acids and several spectroscopic techniques to examine whether guanidinium chloride, one of the most commonly used protein denaturants, and tetrapropylammonium chloride can specifically interact with aromatic side chains. Our results show that tetrapropylammonium, but not guanidinium, can preferentially accumulate around aromatic residues and that tetrapropylammonium undergoes a transition at ∼1.3 M to form aggregates. We find that similar to ionic micelles, on one hand, such aggregates can disrupt native hydrophobic interactions, and on the other hand, they can promote α-helix formation in certain peptides.
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18
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Ohto T, Hunger J, Backus EHG, Mizukami W, Bonn M, Nagata Y. Trimethylamine-N-oxide: its hydration structure, surface activity, and biological function, viewed by vibrational spectroscopy and molecular dynamics simulations. Phys Chem Chem Phys 2017; 19:6909-6920. [DOI: 10.1039/c6cp07284d] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Vibrational spectroscopy and molecular simulations revealed the hydrophilicity and hydrophobicity of TMAO in aqueous solution.
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Affiliation(s)
- Tatsuhiko Ohto
- Graduate School of Engineering Science
- Osaka University
- Toyonaka
- Japan
| | | | | | - Wataru Mizukami
- Department of Energy and Material Sciences
- Faculty of Engineering Sciences
- Kyushu University
- Fukuoka
- Japan
| | - Mischa Bonn
- Max Planck Institute for Polymer Research
- 55128 Mainz
- Germany
| | - Yuki Nagata
- Max Planck Institute for Polymer Research
- 55128 Mainz
- Germany
- Department of Theoretical and Computational Molecular Science
- Institute for Molecular Science
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19
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Lehmkühler F, Forov Y, Elbers M, Steinke I, Sahle CJ, Weis C, Tsuji N, Itou M, Sakurai Y, Poulain A, Sternemann C. Temperature dependence of the hydrogen bond network in trimethylamine N-oxide and guanidine hydrochloride–water solutions. Phys Chem Chem Phys 2017; 19:28470-28475. [DOI: 10.1039/c7cp04958g] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present an X-ray Compton scattering study on aqueous trimethylamine N-oxide (TMAO) and guanidine hydrochloride solutions (GdnHCl) as a function of temperature.
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Affiliation(s)
- Felix Lehmkühler
- Deutsches Elektronen-Synchrotron DESY
- 22607 Hamburg
- Germany
- The Hamburg Centre for Ultrafast Imaging
- 22761 Hamburg
| | - Yury Forov
- Fakultät Physik/DELTA
- Technische Universität Dortmund
- 44221 Dortmund
- Germany
| | - Mirko Elbers
- Fakultät Physik/DELTA
- Technische Universität Dortmund
- 44221 Dortmund
- Germany
| | - Ingo Steinke
- Deutsches Elektronen-Synchrotron DESY
- 22607 Hamburg
- Germany
- The Hamburg Centre for Ultrafast Imaging
- 22761 Hamburg
| | | | - Christopher Weis
- Fakultät Physik/DELTA
- Technische Universität Dortmund
- 44221 Dortmund
- Germany
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20
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Muttathukattil AN, Reddy G. Osmolyte Effects on the Growth of Amyloid Fibrils. J Phys Chem B 2016; 120:10979-10989. [DOI: 10.1021/acs.jpcb.6b09215] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Aswathy N. Muttathukattil
- Solid State and Structural
Chemistry Unit, Indian Institute of Science, Bangalore 560012, Karnataka, India
| | - Govardhan Reddy
- Solid State and Structural
Chemistry Unit, Indian Institute of Science, Bangalore 560012, Karnataka, India
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21
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Yancey PH, Siebenaller JF. Co-evolution of proteins and solutions: protein adaptation versus cytoprotective micromolecules and their roles in marine organisms. ACTA ACUST UNITED AC 2016; 218:1880-96. [PMID: 26085665 DOI: 10.1242/jeb.114355] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Organisms experience a wide range of environmental factors such as temperature, salinity and hydrostatic pressure, which pose challenges to biochemical processes. Studies on adaptations to such factors have largely focused on macromolecules, especially intrinsic adaptations in protein structure and function. However, micromolecular cosolutes can act as cytoprotectants in the cellular milieu to affect biochemical function and they are now recognized as important extrinsic adaptations. These solutes, both inorganic and organic, have been best characterized as osmolytes, which accumulate to reduce osmotic water loss. Singly, and in combination, many cosolutes have properties beyond simple osmotic effects, e.g. altering the stability and function of proteins in the face of numerous stressors. A key example is the marine osmolyte trimethylamine oxide (TMAO), which appears to enhance water structure and is excluded from peptide backbones, favoring protein folding and stability and counteracting destabilizers like urea and temperature. Co-evolution of intrinsic and extrinsic adaptations is illustrated with high hydrostatic pressure in deep-living organisms. Cytosolic and membrane proteins and G-protein-coupled signal transduction in fishes under pressure show inhibited function and stability, while revealing a number of intrinsic adaptations in deep species. Yet, intrinsic adaptations are often incomplete, and those fishes accumulate TMAO linearly with depth, suggesting a role for TMAO as an extrinsic 'piezolyte' or pressure cosolute. Indeed, TMAO is able to counteract the inhibitory effects of pressure on the stability and function of many proteins. Other cosolutes are cytoprotective in other ways, such as via antioxidation. Such observations highlight the importance of considering the cellular milieu in biochemical and cellular adaptation.
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Affiliation(s)
- Paul H Yancey
- Department of Biology, Whitman College, Walla Walla, WA 99362, USA
| | - Joseph F Siebenaller
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
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22
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Ding B, Hilaire MR, Gai F. Infrared and Fluorescence Assessment of Protein Dynamics: From Folding to Function. J Phys Chem B 2016; 120:5103-13. [PMID: 27183318 DOI: 10.1021/acs.jpcb.6b03199] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
While folding or performing functions, a protein can sample a rich set of conformational space. However, experimentally capturing all of the important motions with sufficient detail to allow a mechanistic description of their dynamics is nontrivial since such conformational events often occur over a wide range of time and length scales. Therefore, many methods have been employed to assess protein conformational dynamics, and depending on the nature of the conformational transition in question, some may be more advantageous than others. Herein, we describe our recent efforts, and also those of others, wherever appropriate, to use infrared- and fluorescence-based techniques to interrogate protein folding and functional dynamics. Specifically, we focus on discussing how to use extrinsic spectroscopic probes to enhance the structural resolution of these techniques and how to exploit various cross-linking strategies to acquire dynamic and mechanistic information that was previously difficult to attain.
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Affiliation(s)
- Bei Ding
- Department of Chemistry and ‡The Ultrafast Optical Processes Laboratory, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
| | - Mary Rose Hilaire
- 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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23
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Deb P, Haldar T, Kashid SM, Banerjee S, Chakrabarty S, Bagchi S. Correlating Nitrile IR Frequencies to Local Electrostatics Quantifies Noncovalent Interactions of Peptides and Proteins. J Phys Chem B 2016; 120:4034-46. [DOI: 10.1021/acs.jpcb.6b02732] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Pranab Deb
- Physical and Materials Chemistry
Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India
| | - Tapas Haldar
- Physical and Materials Chemistry
Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India
| | - Somnath M Kashid
- Physical and Materials Chemistry
Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India
| | - Subhrashis Banerjee
- Physical and Materials Chemistry
Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India
| | - Suman Chakrabarty
- Physical and Materials Chemistry
Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India
| | - Sayan Bagchi
- Physical and Materials Chemistry
Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India
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24
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Meuzelaar H, Panman MR, Woutersen S. Guanidinium-Induced Denaturation by Breaking of Salt Bridges. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201508601] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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25
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Meuzelaar H, Panman MR, Woutersen S. Guanidinium-Induced Denaturation by Breaking of Salt Bridges. Angew Chem Int Ed Engl 2015; 54:15255-9. [DOI: 10.1002/anie.201508601] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Indexed: 11/11/2022]
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26
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Rahman S, Warepam M, Singh LR, Dar TA. A current perspective on the compensatory effects of urea and methylamine on protein stability and function. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 119:129-36. [PMID: 26095775 DOI: 10.1016/j.pbiomolbio.2015.06.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Revised: 06/16/2015] [Accepted: 06/17/2015] [Indexed: 11/16/2022]
Abstract
Urea is a strong denaturant and inhibits many enzymes but is accumulated intracellularly at very high concentrations (up to 3-4 M) in mammalian kidney and in many marine fishes. It is known that the harmful effects of urea on the macromolecular structure and function is offset by the accumulation of an osmolytic agent called methylamine. Intracellular concentration of urea to methylamines falls in the ratio of 2:1 to 3:2 (molar ratio). At this ratio, the thermodynamic effects of urea and methylamines on protein stability and function are believed to be algebraically additive. The mechanism of urea-methylamine counteraction has been widely investigated on various approaches including, thermodynamic, structural and functional aspects. Recent advances have also revealed atomic level insights of counteraction and various molecular dynamic simulation studies have yielded significant molecular level informations on the interaction between urea and methylamines with proteins. It is worthwhile that urea-methylamine system not only plays pivotal role for the survival and functioning of the renal medullary cells but also is a key osmoregulatory component of the marine elasmobranchs, holocephalans and coelacanths. Therefore, it is important to combine all discoveries and discuss the developments in context to physiology of the mammalian kidney and adaptation of the marine organisms. In this article we have for the first time reviewed all major developments on urea-counteraction systems to date. We have also discussed about other additional urea-counteraction systems discovered so far including urea-NaCl, urea-myoinsoitol and urea-molecular chaperone systems. Insights for the possible future research have also been highlighted.
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Affiliation(s)
- Safikur Rahman
- Dr. B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi 110 007, India
| | - Marina Warepam
- Dr. B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi 110 007, India
| | - Laishram R Singh
- Dr. B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi 110 007, India
| | - Tanveer Ali Dar
- Clinical Biochemistry, University of Kashmir, Srinagar, Jammu & Kashmir 190006, India.
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27
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Ganguly P, Hajari T, Shea JE, van der Vegt NFA. Mutual Exclusion of Urea and Trimethylamine N-Oxide from Amino Acids in Mixed Solvent Environment. J Phys Chem Lett 2015; 6:581-5. [PMID: 26262470 DOI: 10.1021/jz502634k] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
We study the solvation of amino acids in pure-osmolyte and mixed-osmolyte urea and trimethylamine N-oxide (TMAO) solutions using molecular dynamics simulations. Analysis of Kirkwood-Buff integrals between the solution components provides evidence that in the mixed osmolytic solution, both urea and TMAO are mutually excluded from the amino acid surface, accompanied by an increase in osmolyte-osmolyte aggregation. Similar observations are made in simulations of a model protein backbone, represented by triglycine, and suggest that TMAO stabilizes proteins under urea denaturation conditions by effectively removing urea from the protein surface. The effects of the mixed osmolytes on the solvation of the amino acids and the backbone are found to be highly nonlinear in terms of the effects of the individual osmolytes and independent of differences in the strength of the TMAO-water interactions, as observed with different TMAO force fields.
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Affiliation(s)
- Pritam Ganguly
- §Eduard-Zintl-Institut für Anorganische und Physikalische Chemie and Center of Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Straße 10, Darmstadt 64287, Germany
| | - Timir Hajari
- §Eduard-Zintl-Institut für Anorganische und Physikalische Chemie and Center of Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Straße 10, Darmstadt 64287, Germany
| | | | - Nico F A van der Vegt
- §Eduard-Zintl-Institut für Anorganische und Physikalische Chemie and Center of Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Straße 10, Darmstadt 64287, Germany
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28
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Abstract
Intrinsically disordered proteins (IDPs) are a unique class of proteins that have no stable native structure, a feature that allows them to adopt a wide variety of extended and compact conformations that facilitate a large number of vital physiological functions. One of the most well-known IDPs is the microtubule-associated tau protein, which regulates microtubule growth in the nervous system. However, dysfunctions in tau can lead to tau oligomerization, fibril formation, and neurodegenerative disease, including Alzheimer's disease. Using a combination of simulations and experiments, we explore the role of osmolytes in regulating the conformation and aggregation propensities of the R2/wt peptide, a fragment of tau containing the aggregating paired helical filament (PHF6*). We show that the osmolytes urea and trimethylamine N-oxide (TMAO) shift the population of IDP monomer structures, but that no new conformational ensembles emerge. Although urea halts aggregation, TMAO promotes the formation of compact oligomers (including helical oligomers) through a newly proposed mechanism of redistribution of water around the perimeter of the peptide. We put forth a "superposition of ensembles" hypothesis to rationalize the mechanism by which IDP structure and aggregation is regulated in the cell.
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29
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Abstract
Infrared spectroscopy has played an instrumental role in the study of a wide variety of biological questions. However, in many cases, it is impossible or difficult to rely on the intrinsic vibrational modes of biological molecules of interest, such as proteins, to reveal structural and environmental information in a site-specific manner. To overcome this limitation, investigators have dedicated many recent efforts to the development and application of various extrinsic vibrational probes that can be incorporated into biological molecules and used to site-specifically interrogate their structural or environmental properties. In this review, we highlight recent advancements in this rapidly growing research area.
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30
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Reddy PM, Taha M, Sharma YVRK, Venkatesu P, Lee MJ. Quantifying the co-solvent effects on trypsin from the digestive system of carp Catla catla by biophysical techniques and molecular dynamics simulations. RSC Adv 2015. [DOI: 10.1039/c5ra01302j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Urea molecules locate within 0.5 nm of the surface of trypsin.
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Affiliation(s)
- P. Madhusudhana Reddy
- Department of Chemistry
- University of Delhi
- Delhi – 110 007
- India
- Department of Chemical Engineering
| | - M. Taha
- CICECO
- Departamento de Química
- Universidade de Aveiro
- 3810-193 Aveiro
- Portugal
| | | | | | - Ming-Jer Lee
- Department of Chemical Engineering
- National Taiwan University of Science & Technology
- Taipei 10607
- Taiwan
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31
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Chen HC, Mai FD, Yang KH, Chen LY, Yang CP, Liu YC. Quantitative evaluation on activated property-tunable bulk liquid water with reduced hydrogen bonds using deconvoluted Raman spectroscopy. Anal Chem 2014; 87:808-15. [PMID: 25471522 DOI: 10.1021/ac5039434] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Interesting properties of water with distinguishable hydrogen-bonding structure on interfacial phase or in confined environment have drawn wide attentions. However, these unique properties of water are only found within the interfacial phase and confined environment, thus, their applications are limited. In addition, quantitative evaluation on these unique properties associating with the enhancement of water's physical and chemical activities represents a notable challenge. Here we report a practicable production of free-standing liquid water at room temperature with weak hydrogen-bonded structure naming Au nanoparticles (NPs)-treated (AuNT) water via treating by plasmon-induced hot electron transfer occurred on resonantly illuminated gold NPs (AuNPs). Compared to well-known untreated bulk water (deionized water), the prepared AuNT water exhibits many distinct activities in generally physical and chemical reactions, such as high solubilities to NaCl and O2. Also, reducing interaction energy within water molecules provides lower overpotential and higher efficiency in electrolytic hydrogen production. In addition, these enhanced catalytic activities of AuNT water are tunable by mixing with deionized water. Also, most of these tunable activities are linearly proportional to its degree of nonhydrogen-bonded structure (DNHBS), which is derived from the O-H stretching in deconvoluted Raman spectrum.
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Affiliation(s)
- Hsiao-Chien Chen
- Department of Biochemistry and Molecular Cell Biology, School of Medicine, College of Medicine, Taipei Medical University , No. 250, Wuxing St., Taipei 11031, Taiwan
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32
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Bandyopadhyay D, Mohan S, Ghosh SK, Choudhury N. Molecular Dynamics Simulation of Aqueous Urea Solution: Is Urea a Structure Breaker? J Phys Chem B 2014; 118:11757-68. [DOI: 10.1021/jp505147u] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Dibyendu Bandyopadhyay
- Heavy water Division and ‡Theoretical Chemistry
Section, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Sadhana Mohan
- Heavy water Division and ‡Theoretical Chemistry
Section, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Swapan K. Ghosh
- Heavy water Division and ‡Theoretical Chemistry
Section, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Niharendu Choudhury
- Heavy water Division and ‡Theoretical Chemistry
Section, Bhabha Atomic Research Centre, Mumbai 400 085, India
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33
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Macdonald RD, Khajehpour M. Effects of the protein denaturant guanidinium chloride on aqueous hydrophobic contact-pair interactions. Biophys Chem 2014; 196:25-32. [PMID: 25268875 DOI: 10.1016/j.bpc.2014.08.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 08/20/2014] [Accepted: 08/20/2014] [Indexed: 11/19/2022]
Abstract
Guanidinium chloride (GdmCl) is one of the most common protein denaturants. Although GdmCl is well known in the field of protein folding, the mechanism by which it denatures proteins is not well understood. In fact, there are few studies looking at its effects on hydrophobic interactions. In this work the effect of GdmCl on hydrophobic interactions has been studied by observing how the denaturant influences model systems of phenyl and alkyl hydrophobic contact pairs. Contact pair formation is monitored through the use of fluorescence spectroscopy, i.e., measuring the intrinsic phenol fluorescence being quenched by carboxylate ions. Hydrophobic interactions are isolated from other interactions through a previously developed methodology. The results show that GdmCl does not significantly affect hydrophobic interactions between small moieties such as methyl groups and phenol; while on the other hand, the interaction of larger hydrophobes such as hexyl and heptyl groups with phenol is significantly destabilized.
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Affiliation(s)
- Ryan D Macdonald
- Department of Chemistry, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - Mazdak Khajehpour
- Department of Chemistry, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.
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34
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Microscopic insights into the protein-stabilizing effect of trimethylamine N-oxide (TMAO). Proc Natl Acad Sci U S A 2014; 111:8476-81. [PMID: 24912147 DOI: 10.1073/pnas.1403224111] [Citation(s) in RCA: 183] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Although it is widely known that trimethylamine N-oxide (TMAO), an osmolyte used by nature, stabilizes the folded state of proteins, the underlying mechanism of action is not entirely understood. To gain further insight into this important biological phenomenon, we use the C≡N stretching vibration of an unnatural amino acid, p-cyano-phenylalanine, to directly probe how TMAO affects the hydration and conformational dynamics of a model peptide and a small protein. By assessing how the lineshape and spectral diffusion properties of this vibration change with cosolvent conditions, we are able to show that TMAO achieves its protein-stabilizing ability through the combination of (at least) two mechanisms: (i) It decreases the hydrogen bonding ability of water and hence the stability of the unfolded state, and (ii) it acts as a molecular crowder, as suggested by a recent computational study, that can increase the stability of the folded state via the excluded volume effect.
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35
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Ghosh A, Tucker MJ, Gai F. 2D IR spectroscopy of histidine: probing side-chain structure and dynamics via backbone amide vibrations. J Phys Chem B 2014; 118:7799-805. [PMID: 24712671 PMCID: PMC4317052 DOI: 10.1021/jp411901m] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
It is well known that histidine is involved in many biological functions due to the structural versatility of its side chain. However, probing the conformational transitions of histidine in proteins, especially those occurring on an ultrafast time scale, is difficult. Herein we show, using a histidine dipeptide as a model, that it is possible to probe the tautomer and protonation status of a histidine residue by measuring the two-dimensional infrared (2D IR) spectrum of its amide I vibrational transition. Specifically, for the histidine dipeptide studied, the amide unit of the histidine gives rise to three spectrally resolvable amide I features at approximately 1630, 1644, and 1656 cm(-1), respectively, which, based on measurements at different pH values and frequency calculations, are assigned to a τ tautomer (1630 cm(-1) component) and a π tautomer with a hydrated (1644 cm(-1) component) or dehydrated (1656 cm(-1) component) amide. Because of the intrinsic ultrafast time resolution of 2D IR spectroscopy, we believe that the current approach, when combined with the isotope editing techniques, will be useful in revealing the structural dynamics of key histidine residues in proteins that are important for function.
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Affiliation(s)
- Ayanjeet Ghosh
- Department of Chemistry, University of Pennsylvania , Philadelphia, Pennsylvania 19104-6323, United States
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36
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Gonzalez JD, Levonyak NS, Schneider SC, Smith MJ, Cremeens ME. Using infrared spectroscopy of a nitrile labeled phenylalanine and tryptophan fluorescence to probe the α-MSH peptide’s side-chain interactions with a micelle model membrane. J Mol Struct 2014. [DOI: 10.1016/j.molstruc.2013.09.059] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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37
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Abstract
In cells, biological molecules function in an aqueous solution. Electrolytes and other small molecules play important roles in keeping the osmotic pressure of the cellular environment as well as the structure formation and function of biomolecules. The observed empirical rules such as Hofmeister series are still waiting for molecular interpretations. In this Perspective, we will discuss a simple and self-consistent theory that takes into account the cooperative effects of cations and anions in affecting water/air surface tension, water activity, and the solubility of model compounds including polypeptides. Molecular dynamics simulations used to test these theoretical models will also be discussed.
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Affiliation(s)
- Wen Jun Xie
- Institute of Theoretical and Computational Chemistry, College of Chemistry and Molecular Engineering, Peking National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China
| | - Yi Qin Gao
- Institute of Theoretical and Computational Chemistry, College of Chemistry and Molecular Engineering, Peking National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China
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38
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Huerta-Viga A, Woutersen S. Protein Denaturation with Guanidinium: A 2D-IR Study. J Phys Chem Lett 2013; 4:3397-3401. [PMID: 24163724 PMCID: PMC3805561 DOI: 10.1021/jz401754b] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 09/23/2013] [Indexed: 05/13/2023]
Abstract
Guanidinium (Gdm+) is a widely used denaturant, but it is still largely unknown how it operates at the molecular level. In particular, the effect of guanidinium on the different types of secondary structure motifs of proteins is at present not clear. Here, we use two-dimensional infrared spectroscopy (2D-IR) to investigate changes in the secondary structure of two proteins with mainly α-helical or β-sheet content upon addition of Gdm-13C15N3·Cl. We find that upon denaturation, the β-sheet protein shows a complete loss of β-sheet structure, whereas the α-helical protein maintains most of its secondary structure. These results suggest that Gdm+ disrupts β-sheets much more efficiently than α-helices, possibly because in the former, hydrophobic interactions are more important and the number of dangling hydrogen bonds is larger.
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39
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Carr JK, Buchanan LE, Schmidt JR, Zanni MT, Skinner JL. Structure and dynamics of urea/water mixtures investigated by vibrational spectroscopy and molecular dynamics simulation. J Phys Chem B 2013; 117:13291-300. [PMID: 23841646 DOI: 10.1021/jp4037217] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Urea/water is an archetypical "biological" mixture and is especially well-known for its relevance to protein thermodynamics as urea acts as a protein denaturant at high concentration. This behavior has given rise to an extended debate concerning urea's influence on water structure. On the basis of a variety of methods and of definitions of the water structure, urea has been variously described as a structure-breaker, a structure-maker, or as remarkably neutral toward water. Because of its sensitivity to microscopic structure and dynamics, vibrational spectroscopy can help resolve these debates. We report experimental and theoretical spectroscopic results for the OD stretch of HOD/H2O/urea mixtures (linear IR, 2DIR, and pump-probe anisotropy decay) and for the CO stretch of urea-D4/D2O mixtures (linear IR only). Theoretical results are obtained using existing approaches for water and a modification of a frequency map developed for acetamide. All absorption spectra are remarkably insensitive to urea concentration, consistent with the idea that urea only very weakly perturbs the water structure. Both this work and experiments by Rezus and Bakker, however, show that water's rotational dynamics are slowed down by urea. Analysis of the simulations casts doubt on the suggestion that urea immobilizes particular doubly hydrogen bonded water molecules.
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Affiliation(s)
- J K Carr
- Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin , Madison, Wisconsin 53706, United States
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40
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Larini L, Shea JE. Double Resolution Model for Studying TMAO/Water Effective Interactions. J Phys Chem B 2013; 117:13268-77. [DOI: 10.1021/jp403635g] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Luca Larini
- Department of Chemistry
and Biochemistry
and of Physics, University of California, Santa Barbara, Santa Barbara, California 93106, United
States
| | - Joan-Emma Shea
- Department of Chemistry
and Biochemistry
and of Physics, University of California, Santa Barbara, Santa Barbara, California 93106, United
States
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