REGULATION OF KETO ACID DEHYDROGENSES IN THE HEART

拟议研究计划的主要目标是阐明 调节机制的两个多酶复合物参与 心脏组织中的微生物能量产生。 的调节 丙酮酸和支链α-酮酸脱氢酶 复合物通过两种形式的共价修饰（例如，磷酸化和 酰化）将使用来自 牛心脏，分离的大鼠心脏线粒体和在分离的灌注 鼠心 我们的论点将寻求实验的支持， 这两种酶复合物被它们各自的天然酶激活， 底物但被另一复合物的底物灭活，例如， 丙酮酸激活丙酮酸脱氢酶，但使支链 复合物，而支链α-酮酸活化支链 链复合物，但不包括丙酮酸复合物。 特别感兴趣的 我们认为丙酮酸脱氢酶激酶可能 通过各种α-酮酸底物的酰化/乙酰化调节，或 辅酶A衍生物。 最后，各种代谢和 调节丙酮酸和支链的激素状态 脱氢酶复合物将在灌注心脏中进行研究 准备工作 有人提出实验来检验胰岛素 对丙酮酸脱氢酶复合物发挥其刺激作用， （例如，含二硫化物）介体物质 丙酮酸脱氢酶激酶上的反应性巯基部分。 是 预计拟议的研究将提供必要的和独特的 如何调节这两个非常重要的酶的看法， 复合物对于维持适当的能量至关重要 在我的心肌中产生能力。

The major objective of the proposed research program is to elucidate regulatory mechanisms for two multienzyme complexes involved in mirochondrial energy production in cardiac tissue. The regulation of the pyruvate and the branched chain Alpha-keto acid dehydrogenase enzyme complexes by two forms of covalent modification (e.g., phosphorylation and acylation) will be investigated using the purified enzyme complexes from bovine heart, isolated rat heart mitochondria and in the isolated perfused rat heart. Experimental support will be sought for our contention that these two enzyme complexes are activated by their respective natural substrates but inactivated by the substrates for the other complex, e.g., pyruvate activates pyruvate dehydrogenase but inactivate the branched chain complex while the branched chain Alpha-keto acids activate the branched chain complex but inactivate the pyruvate complex. Of particular interest will be our suggestion that the pyruvate dehydrogenase kinase may be regulated by acylation/acetylation by various Alpha-keto acid substrates or Coenzyme A derivatives. Finally, the effects of various metabolic and hormonal states on the regulation of the pyruvate and branched chain dehydrogenase complexes will be investigated in perfused heart preparations. Experiments are proposed to test a suggestion that insulin exerts its stimulatory effect on the pyruvate dehydrogenase complex through an effect of a (e.g., disulfide containing) mediator substance on a reactive thiol moiety on the pyruvate dehydrogenase kinase. It is anticipated that the proposed studies will provide a necessary and unique perception of how the regulation of these two very important enzyme complexes is crucial for the maintenance of an appropriate energy generating capability in my myocardium.