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Hidden Conformational States and Strange Temperature Optima in Enzyme Catalysis

[Image: see text] The existence of temperature optima in enzyme catalysis that occur before protein melting sets in can be described by different types of kinetic models. Such optima cause distinctly curved Arrhenius plots and have, for example, been observed in several cold-adapted enzymes from psy...

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Autores principales: Åqvist, Johan, Sočan, Jaka, Purg, Miha
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2020
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7584337/
https://www.ncbi.nlm.nih.gov/pubmed/32975950
http://dx.doi.org/10.1021/acs.biochem.0c00705
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author Åqvist, Johan
Sočan, Jaka
Purg, Miha
author_facet Åqvist, Johan
Sočan, Jaka
Purg, Miha
author_sort Åqvist, Johan
collection PubMed
description [Image: see text] The existence of temperature optima in enzyme catalysis that occur before protein melting sets in can be described by different types of kinetic models. Such optima cause distinctly curved Arrhenius plots and have, for example, been observed in several cold-adapted enzymes from psychrophilic species. The two main explanations proposed for this behavior either invoke conformational equilibria with inactive substrate-bound states or postulate differences in heat capacity between the reactant and transition states. Herein, we analyze the implications of the different types of kinetic models in terms of apparent activation enthalpies, entropies, and heat capacities, using the catalytic reaction of a cold-adapted α-amylase as a prototypic example. We show that the behavior of these thermodynamic activation parameters is fundamentally different between equilibrium and heat capacity models, and in the α-amylase case, computer simulations have shown the former model to be correct. A few other enzyme-catalyzed reactions are also discussed in this context.
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spelling pubmed-75843372020-10-26 Hidden Conformational States and Strange Temperature Optima in Enzyme Catalysis Åqvist, Johan Sočan, Jaka Purg, Miha Biochemistry [Image: see text] The existence of temperature optima in enzyme catalysis that occur before protein melting sets in can be described by different types of kinetic models. Such optima cause distinctly curved Arrhenius plots and have, for example, been observed in several cold-adapted enzymes from psychrophilic species. The two main explanations proposed for this behavior either invoke conformational equilibria with inactive substrate-bound states or postulate differences in heat capacity between the reactant and transition states. Herein, we analyze the implications of the different types of kinetic models in terms of apparent activation enthalpies, entropies, and heat capacities, using the catalytic reaction of a cold-adapted α-amylase as a prototypic example. We show that the behavior of these thermodynamic activation parameters is fundamentally different between equilibrium and heat capacity models, and in the α-amylase case, computer simulations have shown the former model to be correct. A few other enzyme-catalyzed reactions are also discussed in this context. American Chemical Society 2020-09-25 2020-10-13 /pmc/articles/PMC7584337/ /pubmed/32975950 http://dx.doi.org/10.1021/acs.biochem.0c00705 Text en This is an open access article published under a Creative Commons Attribution (CC-BY) License (http://pubs.acs.org/page/policy/authorchoice_ccby_termsofuse.html) , which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited.
spellingShingle Åqvist, Johan
Sočan, Jaka
Purg, Miha
Hidden Conformational States and Strange Temperature Optima in Enzyme Catalysis
title Hidden Conformational States and Strange Temperature Optima in Enzyme Catalysis
title_full Hidden Conformational States and Strange Temperature Optima in Enzyme Catalysis
title_fullStr Hidden Conformational States and Strange Temperature Optima in Enzyme Catalysis
title_full_unstemmed Hidden Conformational States and Strange Temperature Optima in Enzyme Catalysis
title_short Hidden Conformational States and Strange Temperature Optima in Enzyme Catalysis
title_sort hidden conformational states and strange temperature optima in enzyme catalysis
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7584337/
https://www.ncbi.nlm.nih.gov/pubmed/32975950
http://dx.doi.org/10.1021/acs.biochem.0c00705
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