Regulation The citric acid cycle is regulated at the steps catalyzed by citrate synthase, isocitrare dehydrogenase and keoglutarate dehydrogenase via feedback inhibition by ATP, citrate, NADH and succinyl CoA, and stimulation of isocitrare dehydrogenase by ADP
Regulation • The citric acid cycle is regulated at the steps catalyzed by citrate synthase, isocitrare dehydrogenase and α– keoglutarate dehydrogenase via feedback inhibition by ATP , citrate, NADH and succinyl CoA , and stimulation of isocitrare dehydrogenade by ADP
Pyruvate dehydrogenase yruvate dehydrogenase is inhibited by acetyl CoA and NADH. In addition, this enzyme is inactivated b phosphory lation, a reaction catalyzed by pyruvate dehydrogenase kinase
Pyruvate dehydrogenase • Pyruvate dehydrogenase is inhibited by acetyl CoA and NADH. In addition, this enzyme is inactivated by phosphorylation, a reaction catalyzed by pyruvate dehydrogenase kinase
Pyruvate dehydrogenase A high ratio of NADH/ NADt, acetyl COA/CoA or ATP/ADP stimulates ph osphorylation of pyruvate dehydro- genase and so inactivates this enzyme Pyruvate inhibits the kinase. Removal of the phosphate group (dephospho- rylation) by a phosphatase reactivates pyrucate dehydrogenase
Pyruvate dehydrogenase • A high ratio of NADH/ NAD+, acetyl CoA/CoA or ATP/ADP stimulates phosphorylation of pyruvate dehydrogenase and so inactivates this enzyme. Pyruvate inhibits the kinase. Removal of the phosphate group (dephosphorylation) by a phosphatase reactivates pyrucate dehydrogenase
mode vivant AT° tyl-CoA, pyruvate dehydrogenass NADH, fatty acids mple AMP,CoA,NAD·,Ca2+ AcetvI-CoA Oxaloacetate Isocitrate LUstrate (ATP maInte ydm量④ca2,ADF NADH Malnte at-Ketoglutarnte FADHO cr-ketoriutnrate Q succinyl-CoA, NADH dehydrogenass ehyrlrogenand SuccinvI-CoA GTE ATP
mode
Biosynthetic pathways ° Amino acids, purines嘌呤and pyrimidines嘧啶, porphyrins卟啉 fatty acids and glucose are all synthesized by pathways that use citric acid intermediates中间体as precursors
Biosynthetic pathways • Amino acids, purines 嘌 呤 and pyrimidines 嘧 啶 , porphyrins 卟 啉 , fatty acids and glucose are all synthesized by pathways that use citric acid intermediates 中间体 as precursors