Friedman M E, Otwell H B, Teggins J E
Biochim Biophys Acta. 1975 May 23;391(1):1-8. doi: 10.1016/0005-2744(75)90145-x.
Mitochondrial malate dehydrogenase (L-malate : NAD-+ oxido-reductase, EC 1.1.1.37) was inhibited by potassium tetrachloro platinum (II), K-2PtCl-4, in the presence of varying concentrations of NADH, NAD-+ and L-malate and mixtures of NAD-+ and L-malate. It was observed that NADH is an effective protector of the enzyme from inhibition while both NAD-+ and L-malate are poor protectors. Spectral studies have suggested that the protection afforded by the substrates are accomplished by reaction with specific groups on the enzyme rather than by complexation of the substrates with PtCl-4-2-minus. From the above data it has been concluded that the tetrachloroplatinate ion binds only at the active site and that this site which is effectively protected by NADH, and moderately protected by a NAD-+-L-malate complex probably contains one or more sulfur containing amino acid side chains. It is also proposed that when the tetrachloroplatinate complexes with the enzyme there is some effect, possibly a conformational change, which causes the release of NADH at the allosteric site.
线粒体苹果酸脱氢酶（L-苹果酸：NAD⁺氧化还原酶，EC 1.1.1.37）在不同浓度的NADH、NAD⁺、L-苹果酸以及NAD⁺与L-苹果酸的混合物存在的情况下，受到四氯铂（II）酸钾（K₂PtCl₄）的抑制。据观察，NADH是该酶免受抑制的有效保护剂，而NAD⁺和L-苹果酸都是较差的保护剂。光谱研究表明，底物提供的保护是通过与酶上的特定基团反应实现的，而不是通过底物与PtCl₄²⁻络合。根据上述数据得出结论，四氯铂酸根离子仅结合在活性位点，该位点受到NADH的有效保护，并受到NAD⁺-L-苹果酸复合物的适度保护，可能含有一个或多个含硫氨基酸侧链。还提出，当四氯铂酸根与酶络合时，会产生某种效应，可能是构象变化，导致变构位点处的NADH释放。
