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Xiong R, Xu L, Tang Y, Cao M, Li H. Identifying the protonation site and the scope of non-proline cis-peptide bond conformations: a first-principles study on protonated oligopeptides. Phys Chem Chem Phys 2023; 25:13989-13998. [PMID: 37194311 DOI: 10.1039/d3cp00690e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The existence of non-proline cis-peptide bond conformations of protonated triglycine proposed by us has been verified through a recent IR-IR double resonance experiment. However, the scope of such unique structures in protonated oligopeptides and whether protonation at amide oxygen is more stable than that at traditional amino nitrogen remain unsolved. In this study, the most stable conformers of a series of protonated oligopeptides were fully searched. Our findings reveal that the special cis-peptide bond structure appears with high energies for diglycine and is energetically less favored for tetra- and pentapeptides, while it acts as the global minimum only for tripeptides. To explore the formation mechanism of the cis-peptide bond, electrostatic potential analysis, and intramolecular interactions were analyzed. Advanced theoretical calculations confirmed that amino nitrogen is still preferred as the protonated site in most cases except glycylalanylglycine(GAG). The energy difference between the two protonated isomers of GAG is only 0.03 kcal mol-1, indicating that the tripeptide is most likely to be protonated on the amide oxygen first. We also conducted chemical (infrared (IR)) and electronic (X-ray photoelectron spectra (XPS) and near-edge X-ray absorption fine structure spectra (NEXAFS)) structure calculations of these peptides to identify their notable differences unambiguously. This study thus provides valuable information for exploring the scope of cis-peptide bond conformation and the competition between two different protonated ways.
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Affiliation(s)
- Rui Xiong
- Institutes of Physical Science and Information Technology, Key Laboratory of Structure and Functional Regulation of Hybrid Materials, Ministry of Education, Anhui Graphene Engineering Laboratory, Anhui University, Hefei, Anhui, 230601, China.
| | - Li Xu
- Institutes of Physical Science and Information Technology, Key Laboratory of Structure and Functional Regulation of Hybrid Materials, Ministry of Education, Anhui Graphene Engineering Laboratory, Anhui University, Hefei, Anhui, 230601, China.
| | - Yong Tang
- Institutes of Physical Science and Information Technology, Key Laboratory of Structure and Functional Regulation of Hybrid Materials, Ministry of Education, Anhui Graphene Engineering Laboratory, Anhui University, Hefei, Anhui, 230601, China.
| | - Mengge Cao
- Institutes of Physical Science and Information Technology, Key Laboratory of Structure and Functional Regulation of Hybrid Materials, Ministry of Education, Anhui Graphene Engineering Laboratory, Anhui University, Hefei, Anhui, 230601, China.
| | - Hongbao Li
- Institutes of Physical Science and Information Technology, Key Laboratory of Structure and Functional Regulation of Hybrid Materials, Ministry of Education, Anhui Graphene Engineering Laboratory, Anhui University, Hefei, Anhui, 230601, China.
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Iliev S, Gocheva G, Ivanova N, Atanasova B, Petrova J, Madjarova G, Ivanova A. Identification and computational characterization of isomers with cis and trans amide bonds in folate and its analogues. Phys Chem Chem Phys 2018; 20:28818-28831. [PMID: 30418443 DOI: 10.1039/c8cp04304c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Folate and its synthetic analogues, called antifolates, are known to have diverse bio-applications, for example as cell proliferation stimulators or anticancer drugs. Their molecular structure is important for performing the required biological activity. Since all folate-derived ligands contain a peptide-like amide bond, its configuration is one of the key components for the functional fitness of such compounds. During the modelling of folate and three of its derivatives - methotrexate, 5-methyl tetrahydrofolate, and pteroyl ornithine, we registered significant population of the cis isomers along the amide bond. The properties of the cis and trans forms of the ligands in saline are studied in detail by classical atomistic molecular dynamics and by quantum chemical methods. The calculations predict high probability for coexistence of the cis isomers for two of the ligands. The energetic instability of the cis form is explained with a σ-character admixture into the C[double bond, length as m-dash]O(π) bond, while its magnitude is attributed to the pattern of local electron density redistribution. The cis forms of all molecules have markedly slower structural dynamics than the trans ones, which might affect their behavior in vivo.
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Affiliation(s)
- Stoyan Iliev
- Laboratory of Quantum and Computational Chemistry, Faculty of Chemistry and Pharmacy, University of Sofia, 1 James Bourchier blvd., 1164 Sofia, Bulgaria.
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Li H, Jiang J, Luo Y. Identification of the protonation site of gaseous triglycine: the cis-peptide bond conformation as the global minimum. Phys Chem Chem Phys 2017; 19:15030-15038. [DOI: 10.1039/c7cp01997a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Extensive ab initio investigations have been performed to characterize stable conformers of protonated triglycine (GGGH) in the gas phase.
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Affiliation(s)
- Hongbao Li
- Hefei National Laboratory for Physical Sciences at the Microscale
- School of Chemistry and Materials Science
- University of Science and Technology of China
- Hefei
- China
| | - Jun Jiang
- Hefei National Laboratory for Physical Sciences at the Microscale
- School of Chemistry and Materials Science
- University of Science and Technology of China
- Hefei
- China
| | - Yi Luo
- Hefei National Laboratory for Physical Sciences at the Microscale
- School of Chemistry and Materials Science
- University of Science and Technology of China
- Hefei
- China
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Fisher KM, Haglund E, Noel JK, Hailey KL, Onuchic JN, Jennings PA. Geometrical Frustration in Interleukin-33 Decouples the Dynamics of the Functional Element from the Folding Transition State Ensemble. PLoS One 2015; 10:e0144067. [PMID: 26630011 PMCID: PMC4667907 DOI: 10.1371/journal.pone.0144067] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 11/12/2015] [Indexed: 12/27/2022] Open
Abstract
Interleukin-33 (IL-33) is currently the focus of multiple investigations into targeting pernicious inflammatory disorders. This mediator of inflammation plays a prevalent role in chronic disorders such as asthma, rheumatoid arthritis, and progressive heart disease. In order to better understand the possible link between the folding free energy landscape and functional regions in IL-33, a combined experimental and theoretical approach was applied. IL-33 is a pseudo- symmetrical protein composed of three distinct structural elements that complicate the folding mechanism due to competition for nucleation on the dominant folding route. Trefoil 1 constitutes the majority of the binding interface with the receptor whereas Trefoils 2 and 3 provide the stable scaffold to anchor Trefoil 1. We identified that IL-33 folds with a three-state mechanism, leading to a rollover in the refolding arm of its chevron plots in strongly native conditions. In addition, there is a second slower refolding phase that exhibits the same rollover suggesting similar limitations in folding along parallel routes. Characterization of the intermediate state and the rate limiting steps required for folding suggests that the rollover is attributable to a moving transition state, shifting from a post- to pre-intermediate transition state as you move from strongly native conditions to the midpoint of the transition. On a structural level, we found that initially, all independent Trefoil units fold equally well until a QCA of 0.35 when Trefoil 1 will backtrack in order to allow Trefoils 2 and 3 to fold in the intermediate state, creating a stable scaffold for Trefoil 1 to fold onto during the final folding transition. The formation of this intermediate state and subsequent moving transition state is a result of balancing the difficulty in folding the functionally important Trefoil 1 onto the remainder of the protein. Taken together our results indicate that the functional element of the protein is geometrically frustrated, requiring the more stable elements to fold first, acting as a scaffold for docking of the functional element to allow productive folding to the native state.
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Affiliation(s)
- Kaitlin M. Fisher
- Department of Chemistry and Biochemistry, University of California at San Diego (UCSD), La Jolla, CA, United States of America
| | - Ellinor Haglund
- Center for Theoretical Biological Physics (CTBP) and Department of Physics, University of California at San Diego (UCSD), La Jolla, CA, United States of America
- Center for Theoretical Biological Physics (CTBP) and Department of Physics and Astronomy, Chemistry and Biochemistry and Cell Biology, Rice University, Houston, TX, United States of America
| | - Jeffrey K. Noel
- Center for Theoretical Biological Physics (CTBP) and Department of Physics and Astronomy, Chemistry and Biochemistry and Cell Biology, Rice University, Houston, TX, United States of America
| | - Kendra L. Hailey
- Department of Chemistry and Biochemistry, University of California at San Diego (UCSD), La Jolla, CA, United States of America
| | - José N. Onuchic
- Center for Theoretical Biological Physics (CTBP) and Department of Physics and Astronomy, Chemistry and Biochemistry and Cell Biology, Rice University, Houston, TX, United States of America
| | - Patricia A. Jennings
- Department of Chemistry and Biochemistry, University of California at San Diego (UCSD), La Jolla, CA, United States of America
- * E-mail:
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Rathi PC, Höffken HW, Gohlke H. Quality matters: extension of clusters of residues with good hydrophobic contacts stabilize (hyper)thermophilic proteins. J Chem Inf Model 2014; 54:355-61. [PMID: 24437522 PMCID: PMC3985445 DOI: 10.1021/ci400568c] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Identifying determinant(s) of protein thermostability is key for rational and data-driven protein engineering. By analyzing more than 130 pairs of mesophilic/(hyper)thermophilic proteins, we identified the quality (residue-wise energy) of hydrophobic interactions as a key factor for protein thermostability. This distinguishes our study from previous ones that investigated predominantly structural determinants. Considering this key factor, we successfully discriminated between pairs of mesophilic/(hyper)thermophilic proteins (discrimination accuracy: ∼80%) and searched for structural weak spots in E. coli dihydrofolate reductase (classification accuracy: 70%).
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Affiliation(s)
- Prakash Chandra Rathi
- Institute for Pharmaceutical and Medicinal Chemistry, Department of Mathematics and Natural Sciences, Heinrich Heine University , Universitätsstr. 1, 40225 Düsseldorf, Germany
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Zhang J, Germann MW. Characterization of secondary amide peptide bond isomerization: thermodynamics and kinetics from 2D NMR spectroscopy. Biopolymers 2011; 95:755-62. [PMID: 21538331 PMCID: PMC3158813 DOI: 10.1002/bip.21642] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Revised: 03/29/2011] [Accepted: 03/31/2011] [Indexed: 11/10/2022]
Abstract
Secondary amide cis peptide bonds are of even lower abundance than the cis tertiary amide bonds of prolines, yet they are of biochemical importance. Using 2D NMR exchange spectroscopy (EXSY) we investigated the formation of cis peptide bonds in several oligopeptides: Ac-G-G-G-NH(2) , Ac-I-G-G-NH(2) , Ac-I-G-G-N-NH(2) and its cyclic form: I-G-G-N in dimethylsulfoxide (DMSO). From the NMR studies, using the amide protons as monitors, an occurrence of 0.13-0.23% of cis bonds was obtained at 296 K. The rate constants for the trans to cis conversion determined from 2D EXSY spectroscopy were 4-9 × 10(-3) s(-1) . Multiple minor conformations were detected for most peptide bonds. From their thermodynamic and kinetic properties the cis isomers are distinguished from minor trans isomers that appear because of an adjacent cis peptide bond. Solvent and sequence effects were investigated utilizing N-methylacetamide (NMA) and various peptides, which revealed a unique enthalpy profile in DMSO. The cyclization of a tetrapeptide resulted in greatly lowered cis populations and slower isomerization rates compared to its linear counterpart, further highlighting the impact of structural constraints.
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Affiliation(s)
- Jin Zhang
- Department of Chemistry and Biology, Georgia State University, Atlanta, GA, USA
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Gutierrez LJ, Baldoni HA, Enriz RD. Conformational and electronic study of cis-peptides (non-proline residues) occurring in natural proteins. J Mol Struct 2009. [DOI: 10.1016/j.molstruc.2009.06.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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8
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Li QG, Xue Y, Yan GS. Water-assisted enol-to-keto tautomerism of a simple peptide model: A computational investigation. ACTA ACUST UNITED AC 2008. [DOI: 10.1016/j.theochem.2008.08.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Mathieu S, Poteau R, Trinquier G. Estimating the "steric clash" at cis peptide bonds. J Phys Chem B 2008; 112:7894-902. [PMID: 18543981 DOI: 10.1021/jp711082d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
To account for the scarcity of cis peptide bonds in proteins, especially in nonproline (or secondary amide) cases, a steric-clash argument is often put forward, in a scheme where the R lateral chains are facing parallel one another, and the backbone is kept in an "all- trans"-like arrangement. Although such a steric conflict can be partly relieved through proper adjustment of the backbone dihedral angles, one can try to estimate its associated energy cost. To this end, quantum-chemistry approaches using a differential-torsion protocol and bond-separation-energy analyses are applied to N-ethyl propionamide CH3-CH2-CO-NH-CH2-CH3, regarded as a model capable of exhibiting C beta...C beta interaction as in alanine succession. The calculations provide an increment of 9 kcal/mol, quite close to that obtained in the nearly isostere (gsg) rotamer of n-hexane (10 kcal/mol), suggesting the local effects induced by methyl-methyl contact are similar in both cases. Analogous treatments on larger radicals as encountered in leucine or phenylalanine dimers do not change this increment much, which therefore defines the basic reference per-plaque quota to be overcome along all- cis chains. Explicit modeling indicated it can be reduced by up to a factor of 4.
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Affiliation(s)
- Simon Mathieu
- Laboratoire de Chimie et Physique Quantique, IRSAMC, Université Paul-Sabatier, Toulouse Cedex 9, France
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Khan MA, Neale C, Michaux C, Pomés R, Privé GG, Woody RW, Bishop RE. Gauging a hydrocarbon ruler by an intrinsic exciton probe. Biochemistry 2007; 46:4565-79. [PMID: 17375935 PMCID: PMC5007129 DOI: 10.1021/bi602526k] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The structural basis of lipid acyl-chain selection by membrane-intrinsic enzymes is poorly understood because most integral membrane enzymes of lipid metabolism have proven refractory to structure determination; however, robust enzymes from the outer membranes of gram-negative bacteria are now providing a first glimpse at the underlying mechanisms. The methylene unit resolution of the phospholipid:lipid A palmitoyltransferase PagP is determined by the hydrocarbon ruler, a 16-carbon saturated acyl-chain-binding pocket buried within the transmembrane beta-barrel structure. Substitution of Gly88 lining the floor of the hydrocarbon ruler with Ala or Met makes the enzyme select specifically 15- or 12-carbon saturated acyl chains, respectively, indicating that hydrocarbon ruler depth determines acyl-chain selection. However, the Gly88Cys PagP resolution does not diminish linearly because it selects both 14- and 15-carbon saturated acyl chains. We discovered that an exciton, emanating from a buried Tyr26-Trp66 phenol-indole interaction, is extinguished by a local structural perturbation arising from the proximal Gly88Cys PagP sulfhydryl group. Site-specific S-methylation of the single Cys afforded Gly88Cys-S-methyl PagP, which reasserted both the exciton and methylene unit resolution by specifically selecting 13-carbon saturated acyl chains for transfer to lipid A. Unlike the other Gly88 substitutions, the Cys sulfhydryl group recedes from the hydrocarbon ruler floor and locally perturbs the subjacent Tyr26 and Trp66 aromatic rings. The resulting hydrocarbon ruler expansion thus occurs at the exciton's expense and accommodates an extra methylene unit in the selected acyl chain. The hydrocarbon ruler-exciton juxtaposition endows PagP with a molecular gauge for probing the structural basis of lipid acyl-chain selection in a membrane-intrinsic environment.
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Affiliation(s)
| | | | | | | | | | | | - Russell E. Bishop
- To whom correspondence should be addressed: Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada L8N 3Z5. Telephone: (905) 525-9140, ext. 28810. Fax: (905) 522-9033.
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Abstract
The conformational study on Ac-Ala-NHMe (the alanine dipeptide) and Ac-Pro-NHMe (the proline dipeptide) is carried out using ab initio HF and density functional methods with the self-consistent reaction field method to explore the differences in the backbone conformational preference and the cis-trans isomerization for the non-prolyl and prolyl residues in the gas phase and in the solutions (chloroform and water). For the alanine and proline dipeptides, with the increase of solvent polarity, the populations of the conformation tC with an intramolecular C(7) hydrogen bond significantly decrease, and those of the polyproline II-like conformation tF and the alpha-helical conformation tA increase, which is in good agreement with the results from circular dichroism and NMR experiments. For both the dipeptides, as the solvent polarity increases, the relative free energy of the cis conformer to the trans conformer decreases and the rotational barrier to the cis-trans isomerization increases. It is found that the cis-trans isomerization proceeds in common through only the clockwise rotation with omega' approximately +120 degrees about the non-prolyl and prolyl peptide bonds in both the gas phase and the solutions. The pertinent distance d(N...H-N(NHMe)) can successfully describe the increase in the rotational barriers for the non-prolyl and prolyl trans-cis isomerization as the solvent polarity increases and the higher barriers for the non-prolyl residue than for the prolyl residue, as seen in experimental and calculated results. By analysis of the contributions to rotational barriers, the cis-trans isomerization for the non-prolyl and prolyl peptide bonds is proven to be entirely enthalpy driven in the gas phase and in the solutions. The calculated cis populations and rotational barriers to the cis-trans isomerization for both the dipeptides in chloroform and/or water accord with the experimental values.
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Affiliation(s)
- Young Kee Kang
- Department of Chemistry and Basic Science Research Institute, Chungbuk National University, Cheongju, Chungbuk 361-763, South Korea.
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Svensson AKE, Zitzewitz JA, Matthews C, Smith VF. The relationship between chain connectivity and domain stability in the equilibrium and kinetic folding mechanisms of dihydrofolate reductase from E.coli. Protein Eng Des Sel 2006; 19:175-85. [PMID: 16452118 PMCID: PMC5441858 DOI: 10.1093/protein/gzj017] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2006] [Accepted: 01/06/2006] [Indexed: 11/14/2022] Open
Abstract
The role of domains in defining the equilibrium and kinetic folding properties of dihydrofolate reductase (DHFR) from Escherichia coli was probed by examining the thermodynamic and kinetic properties of a set of variants in which the chain connectivity in the discontinuous loop domain (DLD) and the adenosine-binding domain (ABD) was altered by permutation. To test the concept that chain cleavage can selectively destabilize the domain in which the N- and C-termini are resident, permutations were introduced at one position within the ABD, one within the DLD and one at a boundary between the domains. The results demonstrated that a continuous ABD is required for a stable thermal intermediate and a continuous DLD is required for a stable urea intermediate. The permutation at the domain interface had both a thermal and urea intermediate. Strikingly, the observable kinetic folding responses of all three permuted proteins were very similar to the wild-type protein. These results demonstrate a crucial role for stable domains in defining the energy surface for the equilibrium folding reaction of DHFR. If domain connectivity affects the kinetic mechanism, the effects must occur in the sub-millisecond time range.
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Kamagata K, Arai M, Kuwajima K. Unification of the Folding Mechanisms of Non-two-state and Two-state Proteins. J Mol Biol 2004; 339:951-65. [PMID: 15165862 DOI: 10.1016/j.jmb.2004.04.015] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2003] [Revised: 04/01/2004] [Accepted: 04/01/2004] [Indexed: 11/15/2022]
Abstract
We have collected the kinetic folding data for non-two-state and two-state globular proteins reported in the literature, and investigated the relationships between the folding kinetics and the native three-dimensional structure of these proteins. The rate constants of formation of both the intermediate and the native state of non-two-state folders were found to be significantly correlated with protein chain length and native backbone topology, which is represented by the absolute contact order and sequence-distant native pairs. The folding rate of two-state folders, which is known to be correlated with the native backbone topology, apparently does not correlate significantly with protein chain length. On the basis of a comparison of the folding rates of the non-two-state and two-state folders, it was found that they are similarly dependent on the parameters that reflect the native backbone topology. This suggests that the mechanisms behind non-two-state and two-state folding are essentially identical. The present results lead us to propose a unified mechanism of protein folding, in which folding occurs in a hierarchical manner, reflecting the hierarchy of the native three-dimensional structure, as embodied in the case of non-two-state folding with an accumulation of the intermediate. Apparently, two-state folding is merely a simplified version of hierarchical folding caused either by an alteration in the rate-limiting step of folding or by destabilization of the intermediate.
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Affiliation(s)
- Kiyoto Kamagata
- Department of Physics, School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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Peterson ME, Eisenthal R, Danson MJ, Spence A, Daniel RM. A New Intrinsic Thermal Parameter for Enzymes Reveals True Temperature Optima. J Biol Chem 2004; 279:20717-22. [PMID: 14973131 DOI: 10.1074/jbc.m309143200] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Two established thermal properties of enzymes are the Arrhenius activation energy and thermal stability. Arising from anomalies found in the variation of enzyme activity with temperature, a comparison has been made of experimental data for the activity and stability properties of five different enzymes with theoretical models. The results provide evidence for a new and fundamental third thermal parameter of enzymes, T(eq), arising from a subsecond timescale-reversible temperature-dependent equilibrium between the active enzyme and an inactive (or less active) form. Thus, at temperatures above its optimum, the decrease in enzyme activity arising from the temperature-dependent shift in this equilibrium is up to two orders of magnitude greater than what occurs through thermal denaturation. This parameter has important implications for our understanding of the connection between catalytic activity and thermostability and of the effect of temperature on enzyme reactions within the cell. Unlike the Arrhenius activation energy, which is unaffected by the source ("evolved") temperature of the enzyme, and enzyme stability, which is not necessarily related to activity, T(eq) is central to the physiological adaptation of an enzyme to its environmental temperature and links the molecular, physiological, and environmental aspects of the adaptation of life to temperature in a way that has not been described previously. We may therefore expect the effect of evolution on T(eq) with respect to enzyme temperature/activity effects to be more important than on thermal stability. T(eq) is also an important parameter to consider when engineering enzymes to modify their thermal properties by both rational design and by directed enzyme evolution.
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Affiliation(s)
- Michelle E Peterson
- Department of Biological Sciences, University of Waikato, Private Bag 3105, Hamilton, New Zealand
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