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Linear Eyring Plots Conceal a Change in the Rate-Limiting Step in an Enzyme Reaction.

ABSTRACT: The temperature dependence of psychrophilic and mesophilic ( R)-3-hydroxybutyrate dehydrogenase steady-state rates yields nonlinear and linear Eyring plots, respectively. Solvent viscosity effects and multiple- and single-turnover pre-steady-state kinetics demonstrate that while product release is rate-limiting at high temperatures for the psychrophilic enzyme, either interconversion between enzyme-substrate and enzyme-product complexes or a step prior to it limits the rate at low temperatures. Unexpectedly, a similar change in the rate-limiting step is observed with the mesophilic enzyme, where a step prior to chemistry becomes rate-limiting at low temperatures. This observation may have implications for past and future interpretations of temperature-rate profiles.

SUBMITTER: Machado TFG

PROVIDER: S-EPMC6300308 | biostudies-literature | 2018 Dec

REPOSITORIES: biostudies-literature

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Linear Eyring Plots Conceal a Change in the Rate-Limiting Step in an Enzyme Reaction.

Machado Teresa F G TFG Gloster Tracey M TM da Silva Rafael G RG

Biochemistry 20181127 49

The temperature dependence of psychrophilic and mesophilic ( R)-3-hydroxybutyrate dehydrogenase steady-state rates yields nonlinear and linear Eyring plots, respectively. Solvent viscosity effects and multiple- and single-turnover pre-steady-state kinetics demonstrate that while product release is rate-limiting at high temperatures for the psychrophilic enzyme, either interconversion between enzyme-substrate and enzyme-product complexes or a step prior to it limits the rate at low temperatures. ...[more]

PMID: 30472832

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