(a) The pyruvate dehydrogenase complex and the a-ketoglutarate dehydrogenase complex have common reaction mechanisms and catalyze chemically similar reactions. However, there are two enzymes that are critical for regulating the pyruvate dehydrogenase complex that are not found in the a-ketoglutarate complex dehydrogenase. What are these regulatory proteins and what is the re-sult of their catalytic action? (b) Through the metabolism of pyruvate and of isocitrate, CO₂ is released with production of NADH. One of these metabolites undergoes oxidative decarboxylation while the other undergoes non- oxidative decarboxylation. On the basis of the structures of the reactant and product for both metabolites show why one reaction is oxidative while the other is non-oxidative even though NAD+ is reduced in both cases. (c) Using structural formulas for the reactions catalyzed by the pyruvate dehydrogenase complex, draw the structures of the corresponding intermediates of the reaction cata-lyzed by a-ketoglutarate dehydrogenase complex. Name the enzymes catalyzing the various steps.

(a) The pyruvate dehydrogenase complex and the a-ketoglutarate dehydrogenase complex have common reaction mechanisms and catalyze chemically similar reactions. However, there are two enzymes that are critical for regulating the pyruvate dehydrogenase complex that are not found in the a-ketoglutarate complex dehydrogenase. What are these regulatory proteins and what is the re-sult of their catalytic action? (b) Through the metabolism of pyruvate and of isocitrate, CO₂ is released with production of NADH. One of these metabolites undergoes oxidative decarboxylation while the other undergoes non- oxidative decarboxylation. On the basis of the structures of the reactant and product for both metabolites show why one reaction is oxidative while the other is non-oxidative even though NAD+ is reduced in both cases. (c) Using structural formulas for the reactions catalyzed by the pyruvate dehydrogenase complex, draw the structures of the corresponding intermediates of the reaction cata-lyzed by a-ketoglutarate dehydrogenase complex. Name the enzymes catalyzing the various steps.

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter25: Nitrogen Acquisition And Amino Acid Metabolism

Section: Chapter Questions

Problem 16P: A Deficiency on 3-Phosphogtycerate Dehydrogenase Can Affect Amino Acid Metabolism Although serine is...

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