海螺肌肉中镁激活型和锰激活型丙酮酸激酶之间的差异。

Differences between magnesium-activated and manganese-activated pyruvate kinase from the muscle of Concholepas concholepas.

作者信息

González R, Carvajal N, Morán A

出版信息

Comp Biochem Physiol B. 1984;78(2):389-92. doi: 10.1016/0305-0491(84)90047-6.

Abstract

In contrast to the Mg2+-activated enzyme, in the presence of Mn2+ pyruvate kinase exhibits hyperbolic kinetics with respect to the substrate phosphoenolpyruvate and is insensitive to fructose 1,6-biphosphate, phenylalanine and alanine. However, with both metal activated species inhibition by excess ADP is observed. In contrast with Mg2+, which affords significant protection against inactivation caused by 5,5'-dithiobis (2-nitrobenzoic acid), the rate of inactivation by this reagent is increased in the presence of Mn2+. Differences in conformational changes induced by combination of pyruvate kinase with Mg2+ or Mn2+ were indicated by u.v. difference spectra.

摘要

与镁离子激活的酶相反，在锰离子存在的情况下，丙酮酸激酶对底物磷酸烯醇丙酮酸呈现双曲线动力学，并且对1,6-二磷酸果糖、苯丙氨酸和丙氨酸不敏感。然而，对于这两种金属激活的酶，均观察到过量二磷酸腺苷（ADP）的抑制作用。与镁离子能有效防止由5,5'-二硫代双（2-硝基苯甲酸）引起的失活相反，在锰离子存在时，该试剂导致的失活速率增加。丙酮酸激酶与镁离子或锰离子结合所诱导的构象变化差异通过紫外差光谱得以体现。