Centro de Estudios Fotosintéticos y Bioquímicos, (CONICET, F.M. Lillo, Universidad Nacional de Rosario), Suipacha 531, 2000, Rosario, Argentina.
Photosynth Res. 1994 Jan;39(1):67-73. doi: 10.1007/BF00027144.
The effect of structural analogues of L-malate was studied on NADP-malic enzyme purified from Zea mays L. leaves. Among the compounds tested, the organic acids behaved as more potent inhibitors at pH 7.0 than at pH 8.0, suggesting that the dimeric form was more susceptible to the inhibition than the tetrameric form of the enzyme.Oxalate, ketomalonate, hydroxymalonate, malonate, oxaloacetate, tartrate, α-hydroxybutyrate, α-ketobutyrate, α-ketoglutarate and α-hydroxyglutarate exhibited linear competitive inhibition with respect to the substrate L-malate at pH 8.0. On the other hand, glyoxylate and glycolate turned out to be non-competitive inhibitors, while glycolaldehyde, succinate, fumarate, maleate and β- and γ-hydroxybutyrate had no effect on the enzyme activity, at the concentrations assayed. These results suggest that the extent of inhibition was dependent on the size of the analogues and that the presence of an 1-carboxyl group along with a 2-hydroxyl or 2-keto group was important for binding of the substrate analogue to the enzyme.
研究了 L-苹果酸的结构类似物对从玉米叶中纯化的 NADP-苹果酸酶的影响。在测试的化合物中，有机酸在 pH7.0 时比在 pH8.0 时表现出更强的抑制作用，这表明二聚体形式比酶的四聚体形式更容易受到抑制。草酸盐、酮戊二酸、羟马来酸、丙二酸、草酰乙酸、酒石酸、α-羟基丁酸、α-酮丁酸、α-酮戊二酸和α-羟基戊二酸在 pH8.0 时对底物 L-苹果酸表现出线性竞争抑制。另一方面，乙醛酸和甘醇酸被证明是非竞争性抑制剂，而乙醛、琥珀酸、富马酸、马来酸以及β-和γ-羟基丁酸在测定的浓度下对酶活性没有影响。这些结果表明，抑制程度取决于类似物的大小，并且 1-羧基与 2-羟基或 2-酮基的存在对于类似物与酶的结合很重要。
