Five coenzymes are required by a-ketoglutarate dehydrogenase, the enzyme in the citric acid cycle that converts a-ketoglutarate to succinyl-CoA.a. Identify the coenzymes.b. Propose a mechanism for the reaction. A-ketoglutarate dehydrogenase A-ketoglutarate succinyl-CoAOO OO O−O O− −O SCoA + CO2

Five coenzymes are required by a-ketoglutarate dehydrogenase, the enzyme in the citric acid cycle that converts a-ketoglutarate to succinyl-CoA.a. Identify the coenzymes.b. Propose a mechanism for the reaction. A-ketoglutarate dehydrogenase A-ketoglutarate succinyl-CoAOO OO O−O O− −O SCoA + CO2

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter19: The Tricarboxylic Acid Cycle

Section: Chapter Questions

Problem 22P: Study Figure 19.18 and decide which of the following statements is false. Pyruvate dehydrogenase is...

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Five coenzymes are required by a-ketoglutarate dehydrogenase, the enzyme in the citric acid cycle that converts a-ketoglutarate to succinyl-CoA.a. Identify the coenzymes.b. Propose a mechanism for the reaction.
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Explain why people with Medium-chain acyl-CoA dehydrogenase deficiency are advised to eat a diet rich in complex carbohydrates. How is this condition normally diagnosed?
When transaminated, the three branched-chain amino acids (valine, leucine, and isoleucine) form compounds that have the characteristic odor of maple syrup. An enzyme known as branched-chain a-keto acid dehydrogenase converts these compounds into CoA esters. People who do not have this enzyme have the genetic disease known as maple syrup urine disease, so called because their urine smells like maple syrup. a. Draw the compounds that smell like maple syrup.b. Draw the CoA esters.c. Branched-chain a-keto acid dehydrogenase has five coenzymes. Identify them.d. Suggest a way to treat maple syrup urine disease.
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Which of the following enzymes possesses a catalytic mechanism extremely similar to that of the Pyruvate Dehydrogenase Complex? A. the isocitrate dehydrogenase B. the succinate dehydrogenase C. the alpha-ketoglutarate dehydrogenase D. the malate dehydrogenase
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Write a balanced equation for the conversion in the glyoxylate cycle of twoacetyl units, as acetyl-CoA, to oxaloacetate.
Under anaerobic conditions, Escherichia coli synthesizes an NADH-dependent fumarate reductase rather than succinatedehydrogenase, the flavoprotein that oxidizes succinate to fumarate. a) Write an equation for the reaction catalyzed by fumarate reductase.b) NADH produced by the glyceraldehyde-3-phosphate dehydrogenase reaction is re-oxidized by reducing an organicintermediate. Rather than reduce pyruvate to lactate, anaerobic E. coli utilize fumarate reductase. However, underanaerobiosis, the activity of -ketoglutarate dehydrogenase is virtually nonexistent. Show how fumarate is formed, usinga reaction beginning with PEP and including the necessary TCA cycle enzymes.c) What is the metabolic advantage to anaerobic E. coli in using the fumarate reductase pathway rather than lactatedehydrogenase to re-oxidize NADH?
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