苹果酸脱氢酶（Malate Dehydrogenase，MDH）（EC 1.1.1.37）广泛存在于动物、植物、微生物和培养细胞中，线粒体中 MDH 是三羧酸循环（TCA）的关键酶之一，催化苹果酸形成草酰乙酸；相反，胞浆中MDH催化草酰乙酸形成苹果酸。草酰乙酸是重要的中间产物，连接多条重要的代谢途径。因此，MDH在细胞多种生理活动中扮演着重要的角色，包括线粒体的能量代谢、苹果酸-天冬氨酸穿梭系统、活性氧代谢和抗病性等。根据不同的辅酶特异性，MDH 分为 NAD-依赖的 MDH 和 NADP-依赖的 MDH。 本试剂盒检测原理是 NADP-MDH 催化 NADPH 还原草酰乙酸生成苹果酸，导致340 nm处光吸收下降。
Malate Dehydrogenase (MDH) (EC 1.1.1.37) is widely present in animals, plants, microorganisms, and cultured cells. In mitochondria, MDH is one of the key enzymes in the tricarboxylic acid (TCA) cycle, catalyzing the conversion of malate to oxaloacetate. Conversely, cytoplasmic MDH catalyzes the formation of malate from oxaloacetate. Oxaloacetate is a crucial intermediate that connects multiple important metabolic pathways. Therefore, MDH plays a significant role in various cellular physiological processes, including mitochondrial energy metabolism, the malate-aspartate shuttle system, reactive oxygen species metabolism, and disease resistance. Based on coenzyme specificity, MDH is classified into NAD-dependent MDH and NADP-dependent MDH. The detection principle of this kit is that NADP-MDH catalyzes the reduction of oxaloacetate by NADPH to generate malate, resulting in a decrease in light absorption at 340 nm.
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