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  • 1
    ISSN: 0948-5023
    Keywords: Keywords: Amides ; Hydrolysis ; Reaction mechanism ; Peptides ; Theoretical calculations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The hydrolysis of amides is a model reaction to study peptide hydrolysis. This process has been previously considered in the literature at the ab initio level. In this work, we revisit different reaction mechanisms (water-assisted, non-assisted, neutral and acid-catalyzed) with various theoretical methods : semiempirical, ab initio and Density Functional. The ab initio calculations are carried out at a computational level which is substantially higher than in previous studies. We describe the structure of the transition states and discuss the influence of the catalyst. We also compute the activation free energies for these processes at the Density Functional Theory level. Comparison of the methods allows to outline the main trends of these theoretical approaches which may be useful to design new computational strategies for investigating biological reaction mechanisms through the use of combined Quantum Mechanics/Molecular Mechanics methods.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0948-5023
    Keywords: Hybrid methods ; QM/MM ; LSCF ; Zinc metalloproteases ; Thermolysin ; Peptide hydrolysis ; Enzymatic mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The hydrolysis by thermolysin of a Gly-Phe-Leu peptide, considered as a model substrate of the enkephalin family, has been studied with a mixed QM/MM method with the AM1/AMBER parameterization. This study is based on the mechanism proposed by Matthews in which the Glu-143 residue plays the role of a proton shuttle in the course of the reaction. The study focused on the description of every step of the process, reaction intermediates and transition states, and on the influence, both energetical and structural, of the whole protein on these stationary points. The overall mechanism appears to be quite realistic, but the study shows that some reaction steps that were assumed to be concerted should occur in two phases. Analysis of the role of the amino-acids surrounding the active site has shown their important participation in the fluctuations of the energy. In particular, the major role of His-231 on the overall mechanism has been confirmed. This study shows that modeling reaction mechanisms for enzymes is quite feasible and opens the way for computer experiments that may be helpful in devising and interpreting detailed experimental investigations.
    Type of Medium: Electronic Resource
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