Changes in Properties of Malate Dehydrogenase Isolated from<i>Solanum nigrum</i>L. Seeds Imbibed at High Temperatures

Plasma membranes were isolated and purified from 14day-old maize roots (Zea mays L.) by two-phase partitioning at a 6.5% polymer concentration, and compared to isolated mitochondria, microsomes, and soluble fraction. Marker enzyme analysis demonstrated that the plasma membranes were devoid of cytoplasmic, mitochondrial, tonoplast, and endoplasmic-reticulum contaminations. Isolated plasma membranes exhibited malate dehydrogenase activity, catalyzing NADH-dependent reduction of oxaloacetate as well as NAD+-dependent malate oxidation. Malate dehydrogenase activity was resistant to osmotic shock, freeze-thaw treatment, and salt washing and stimulated by solubilization with Triton X-100, indicating that the enzyme is tightly bound to the plasma membrane. Malate dehydrogenase activity was highly specific to NAD § and NADH. The enzyme exhibited a high degree of latency in both right-side-out (80%) and inside-out (70%) vesicle preparations. Kinetic and regulatory properties with ATP and P~, as well as pH dependence of plasma-membrane-bound malate dehydrogenase were different from mitochondrial and soluble malate dehydrogenases. Starch gel electrophoresis revealed a characteristic isozyme form present in the plasma membrane isolate, but not present in the soluble, mitochondrial, and microsomal fractions. The results presented show that purified plasma membranes isolated from maize roots contain a tightly associated malate dehydrogenase, having properties different from mitochondrial and soluble malate dehydrogenases.Abbreviations: FCR ferricyanide reductase; MDH malate dehydrogenase.

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Plasma-membrane-bound malate dehydrogenase activity in maize roots

Hadži-Taskovišković

Vuletić

Ignjatović-Micić

et al. 1999

Protoplasma

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Effects of fruit age, fermentation and storage on germination of cucurbit seeds

Nerson

Paris

1988

Scientia Horticulturae

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Malate dehydrogenase in plants: evolution, structure, and a myriad of functions

Baird,

Berndsen,

Monroe

2024

Essays in Biochemistry

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Malate dehydrogenase (MDH) catalyzes the interconversion of oxaloacetate and malate coupled to the oxidation/reduction of coenzymes NAD(P)H/NAD(P)+. While most animals have two isoforms of MDH located in the cytosol and mitochondria, all major groups of land plants have at least six MDHs localized to the cytosol, mitochondria, plastids, and peroxisomes. This family of enzymes participates in important reactions in plant cells including photosynthesis, photorespiration, lipid metabolism, and NH4+ metabolism. MDH also helps to regulate the energy balance in the cell and may help the plant cope with various environmental stresses. Despite their functional diversity, all of the plant MDH enzymes share a similar structural fold and act as dimers. In this review, we will introduce readers to our current understanding of the plant MDHs, including their evolution, structure, and function. The focus will be on the MDH enzymes of the model plant Arabidopsis thaliana.

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Changes in Properties of Malate Dehydrogenase Isolated fromSolanum nigrumL. Seeds Imbibed at High Temperatures

Cited by 3 publications

References 26 publications

Plasma-membrane-bound malate dehydrogenase activity in maize roots

Plasma-membrane-bound malate dehydrogenase activity in maize roots

Effects of fruit age, fermentation and storage on germination of cucurbit seeds

Malate dehydrogenase in plants: evolution, structure, and a myriad of functions

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