[鸽胸肌丙酮酸脱氢酶的协同相互作用]

[Cooperative interaction of pyruvate dehydrogenase from pigeon breast muscle].

作者信息

Khailova L S, Bernkhardt R, Severin S E

出版信息

Biokhimiia. 1976 Aug;41(8):1391-6.

Abstract

Cooperative interaction of pyruvate with the pyruvate dehydrogenase (PD) complex from pigeon breast muscle was shown. The sigmoidal dependence of the reaction rate on pyruvate concentration was observed for the PD complex. The Hill coefficient is equal to 1,5; no inhibition by the substrate (up to 2.2.10(-3) M) was found. The kinetic behaviour of the isolated pyruvate dehydrogenase component (PDH) analyzed under similar conditions, is more complex; this may be probably due to the presence of oligomeric forms with different molecular weights and specific activities. The competitive inhibitor of the PD complex--an amide of pyruvic acid (PA) (Ki=6.3-10(-6) M) activates the enzyme at low concentrations (less than 2,10(-6) M). When PA is present, the dependence of the reaction rate on pyruvate concentration gives a usual hyperbolic curve, v of [S]o. It is concluded that pyruvate may have a regulatory effect on the activity of muscle PD complex.

摘要

已表明丙酮酸与鸽胸肌丙酮酸脱氢酶（PD）复合物存在协同相互作用。观察到PD复合物的反应速率对丙酮酸浓度呈S形依赖关系。希尔系数等于1.5；未发现底物（浓度高达2.2×10⁻³ M）的抑制作用。在相似条件下分析的分离丙酮酸脱氢酶组分（PDH）的动力学行为更为复杂；这可能是由于存在具有不同分子量和比活性的寡聚形式。PD复合物的竞争性抑制剂——丙酮酸酰胺（PA）（Ki = 6.3×10⁻⁶ M）在低浓度（小于2×10⁻⁶ M）时激活该酶。当存在PA时，反应速率对丙酮酸浓度的依赖关系给出通常的双曲线，即v对[S]ₒ。得出结论，丙酮酸可能对肌肉PD复合物的活性具有调节作用。