Lindstad R I, Hermansen L F, McKinley-McKee J S
Institute of Biochemistry, University of Oslo, Blindern, Norway.
Eur J Biochem. 1994 Apr 15;221(2):847-54. doi: 10.1111/j.1432-1033.1994.tb18799.x.
Reversible inhibition and activation, as well as protection against affinity labelling with DL-2-bromo-3-(5-imidazolyl)propionic acid, of sheep liver sorbitol dehydrogenase have been studied. The results presented are discussed in terms of enzyme active-site properties and may have potential applications for drug design. Kinetics with mainly sorbitol competitive inhibitors reveals that aliphatic thiols are generally the most potent inhibitors of enzyme activity. Inhibition and inactivation by heterocyclics parallel that seen previously with sorbitol dehydrogenase from other sources as well as with alcohol dehydrogenase from yeast. However, there are significant differences in relation to the structurally similar horse liver alcohol dehydrogenase, as the catalytic zinc of sorbitol dehydrogenase is more easily removed by chelating molecules. Several aldose reductase inhibitors are shown to also inhibit sorbitol dehydrogenase, but at concentrations unlikely to be reached clinically. Enzyme activation has been observed with various compounds, in particular halo-alcohols and detergents. Several inhibitors provide competitive protection against enzyme inactivation by DL-2-bromo-3-(5-imidazolyl)propionic acid. This enables the dissociation constants for binary enzyme-inhibitor complexes to be determined. NADH protects noncompetitively against inactivation. The presence of some binary and ternary enzyme-NADH complexes is indicated from fluorescence emission spectra, as a shift in the fluorescence maximum and intensity is observed due to their formation.
对绵羊肝脏山梨醇脱氢酶的可逆抑制与激活作用，以及针对DL-2-溴-3-(5-咪唑基)丙酸亲和标记的保护作用进行了研究。根据酶活性位点特性对所呈现的结果进行了讨论，这些结果可能在药物设计中有潜在应用。主要以山梨醇竞争性抑制剂进行的动力学研究表明，脂肪族硫醇通常是酶活性最有效的抑制剂。杂环化合物的抑制和失活作用与之前在其他来源的山梨醇脱氢酶以及酵母乙醇脱氢酶中观察到的情况相似。然而，与结构相似的马肝乙醇脱氢酶存在显著差异，因为山梨醇脱氢酶的催化锌更容易被螯合分子去除。几种醛糖还原酶抑制剂也显示出能抑制山梨醇脱氢酶，但在临床上不太可能达到的浓度下才有此作用。已观察到多种化合物能激活该酶，特别是卤代醇和去污剂。几种抑制剂能为酶抵御DL-2-溴-3-(5-咪唑基)丙酸的失活提供竞争性保护。这使得能够确定二元酶-抑制剂复合物的解离常数。NADH对失活具有非竞争性保护作用。荧光发射光谱表明存在一些二元和三元酶-NADH复合物，因为由于它们的形成，观察到荧光最大值和强度发生了变化。
