Malate dehydrogenase in plants: Its genetics, structure, localization and use as a marker

late: NAD oxidoreductase; EC 1.1.1.37) is an enzyme very commonly occurring in animals, plants and microorganisms. MDH catalyzes the oxidation (dehydration) of L-malate to oxaloacetate in the presence of NAD+ as a cofactor: This article is an overview of literature data on the structure, properties, functions and genetic control of the enzyme malate dehydrogenase (MDH) in plants. In most of the plant entities studied, this enzyme is highly polymorphic, which means that malate dehydrogenase has multiple molecular forms. It has been found that MDH polymorphism in each species is genetically determined by several loci with multiple alleles. A readily identifiable phenotypic manifestation and a high activity of malate dehydrogenase in diverse organs and tissues make this enzyme a reliable and convenient genetic marker, which can effectively be used in special, ecological and population genetics. СООН-СН2-СНОН-СООН + NAD = L-malate СООН-СН2-СО-СООН + NADH + Н oxaloacetate [3]. MDH is a well-studied enzyme. In the cell, malate dehydrogenase exists in various molecular forms. Two MDH forms have been found in most of the plant objects studied: mitochondrial MDH (m-MDH) and cytoplasmic MDH (s-MDH) [4-8]. Mitochondrial MDH functions as part of the Krebs cycle, while soluble (cytoplasmic) MDH can be involved in acid metabolism in plant tissues, in autotrophic carbon dioxide fixation in higher plants and in more other metabolic pathways [9-11]. In plant tissues, MDH has additionally been found in glyoxysomes [6,7, 12,13], peroxisomes [14,15] and microsomes [16-18]. The microbody form of MDH is involved in photorespiration and the glyoxylate cycle [19].