REGULATION OF KETO ACID DEHYDROGENSES IN THE HEART

拟议的研究计划的主要目标是阐明 两种多酶复合体参与的调节机制 心肌组织中线粒体能量的产生。对法律的监管 丙酮酸和支链α-酮酸脱氢酶 通过两种形式的共价修饰(例如，磷酸化和 酰化)将使用纯化的酶复合体从 牛心、大鼠离体心线粒体及在离体灌流液中 老鼠心。我们将为我们的论点寻求实验支持 这两种酶的复合体是由它们各自的天然 底物但被另一络合物的底物失活，例如， 丙酮酸激活丙酮酸脱氢酶但使支链失活 络合物而支链α-酮酸激活支链 链状复合体，但灭活丙酮酸复合体。特别感兴趣的 将是我们认为丙酮酸脱氢酶可能是 受不同α-酮酸底物的酰化/乙酰化或 辅酶A衍生物。最后，各种新陈代谢和 激素状态对丙酮酸和支链的调节 将在灌流的心脏中研究脱氢酶复合体 准备工作。有人提议用实验来检验这样一种说法 通过对丙酮酸脱氢酶复合体的刺激作用 一种(例如，含二硫化物的)介体物质对 丙酮酸脱氢酶上的活性硫醇部分。它是 预期拟议的研究将提供必要和独特的 感知这两种非常重要的酶是如何调节的 络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.