Investigation of the pH dependence of proton uptake by porcine heart mitochondrial malate dehydrogenase upon binding of NADH

Hodges, C T; Jurgensen, Stewart; Harrison, John

doi:10.1016/0003-9861(80)90215-5

Cited by 3 publications

(1 citation statement)

References 18 publications

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“…Our proposed model (Fig. 1 F) is based on the studies on pH-dependent proton uptake upon binding of NADH to the enzyme (49). These authors observed that mMDH exhibits proton uptake upon binding to NADH for pH values >6.0, and suggested the histidine residue to be the cause of proton uptake.…”

Section: Kinetic Mechanismmentioning

confidence: 99%

Determination of the Catalytic Mechanism for Mitochondrial Malate Dehydrogenase

Dasika

Vinnakota

Beard

2015

Biophysical Journal

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The kinetics of malate dehydrogenase (MDH) catalyzed oxidation/reduction of L-malate/oxaloacetate is pH-dependent due to the proton generated/taken up during the reaction. Previous kinetic studies on the mitochondrial MDH did not yield a consensus kinetic model that explains both substrate and pH dependency of the initial velocity. In this study, we propose, to our knowledge, a new kinetic mechanism to explain kinetic data acquired over a range of pH and substrate concentrations. Progress curves in the forward and reverse reaction directions were obtained under a variety of reactant concentrations to identify associated kinetic parameters. Experiments were conducted at physiologically relevant ionic strength of 0.17 M, pH ranging between 6.5 and 9.0, and at 25 °C. The developed model was built on the prior observation of proton uptake upon binding of NADH to MDH, and that the MDH-catalyzed oxidation of NADH may follow an ordered bi-bi mechanism with NADH/NAD binding to the enzyme first, followed by the binding of oxaloacetate/L-malate. This basic mechanism was expanded to account for additional ionic states to explain the pH dependency of the kinetic behavior, resulting in what we believe to be the first kinetic model explaining both substrate and pH dependency of the reaction velocity.

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Section: Kinetic Mechanismmentioning

confidence: 99%

Determination of the Catalytic Mechanism for Mitochondrial Malate Dehydrogenase

Dasika

Vinnakota

Beard

2015

Biophysical Journal

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The N-ethylmaleimide-sensitive cysteine residue in the pH-dependent subunit interactions of malate dehydrogenase.

Wood¹,

Hodges²,

Howell³

et al. 1981

Journal of Biological Chemistry

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Catalytic mechanism and kinetics of malate dehydrogenase

de Lorenzo,

Stack,

Fox

et al. 2024

Essays in Biochemistry

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Malate dehydrogenase (MDH) is a ubiquitous and central enzyme in cellular metabolism, found in all kingdoms of life, where it plays vital roles in the cytoplasm and various organelles. It catalyzes the reversible NAD+-dependent reduction of L-malate to oxaloacetate. This review describes the reaction mechanism for MDH and the effects of mutations in and around the active site on catalytic activity and substrate specificity, with a particular focus on the loop that encloses the active site after the substrates have bound. While MDH exhibits selectivity for its preferred substrates, mutations can alter the specificity of MDH for each cosubstrate. The kinetic characteristics and similarities of a variety of MDH isozymes are summarized, and they illustrate that the KM values are consistent with the relative concentrations of the substrates in cells. As a result of its existence in different cellular environments, MDH properties vary, making it an attractive model enzyme for studying enzyme activity and structure under different conditions.

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Investigation of the pH dependence of proton uptake by porcine heart mitochondrial malate dehydrogenase upon binding of NADH

Cited by 3 publications

References 18 publications

Determination of the Catalytic Mechanism for Mitochondrial Malate Dehydrogenase

Determination of the Catalytic Mechanism for Mitochondrial Malate Dehydrogenase

The N-ethylmaleimide-sensitive cysteine residue in the pH-dependent subunit interactions of malate dehydrogenase.

Catalytic mechanism and kinetics of malate dehydrogenase

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