Wu C Y, Chen S T, Chiou S H, Wang K T
Graduate Institute of Biochemical Sciences, National Taiwan University, Taipei.
Biochem Biophys Res Commun. 1992 Jul 31;186(2):874-80. doi: 10.1016/0006-291x(92)90827-8.
A systematic analysis of the kinetic properties of duck lens epsilon-crystallin with lactate dehydrogenase [LDH, (E.C. 1.1.1.27)] activity was carried out by employing some 19 different alpha-keto acids as substrates for this NADH-dependent LDH-catalyzed reaction. The steady-state Michaelis and catalytic constants (Km, kcat) were determined for a broad range of organic compounds. The results provide important insights regarding the binding and affinity of substrates to active sites of this enzyme crystallin and indicate a great potential for the application of the stable epsilon-crystallin as a catalyst to the synthesis of some important chiral alpha-hydroxyacids in a convenient and efficient way. It is also demonstrated for the first time that in addition to the enzymatic activity of lactate dehydrogenase, duck epsilon-crystallin also possesses the enzymatic activity of malate dehydrogenase.
通过使用约19种不同的α-酮酸作为这种依赖NADH的乳酸脱氢酶（LDH，E.C. 1.1.1.27）催化反应的底物，对鸭晶状体ε-晶体蛋白与乳酸脱氢酶的动力学特性进行了系统分析。测定了一系列有机化合物的稳态米氏常数和催化常数（Km，kcat）。这些结果为底物与这种酶晶体蛋白活性位点的结合和亲和力提供了重要见解，并表明稳定的ε-晶体蛋白作为催化剂以方便、高效的方式合成一些重要的手性α-羟基酸具有巨大潜力。首次证明，除了乳酸脱氢酶的酶活性外，鸭ε-晶体蛋白还具有苹果酸脱氢酶的酶活性。
