Biochemistry: A Short Course - MyWeb | Solutions

Citric Acid Cycle Generates Reductive Equivalents Utilized in Respiration Citric Acid Cycle: A Two Stage Process

Stage One: C4 + C2 condensation C6 tricarboxylic acid Oxidative decarboxylation 2 CO2

Succinyl CoA Net Result: 2NADH + 2CO2 + Succinyl CoA C4 + C2 Condensation Reaction

Condensation catalyzed by enzyme dimer Citrate Synthase RxN Driver

Citrate Synthase Reaction Citrate Synthase Reaction Citrate Synthase Reaction

Citrate Synthase Reaction Citrate to Isocitrate Conversion via Aconitase Hydroxyl shift for subsequent oxidative decarboxylation

Isocitrate Dehydrogenase: Oxidation and Decarboxylation Oxalosuccinate not released from the enzyme -Ketoglutarate Dehydrogenase: Ketoglutarate Dehydrogenase: Oxidation and Decarboxylation

How similar is -Ketoglutarate Dehydrogenase: ketoglutarate dehydrogenase with pyruvate dehydrogenase in terms of substrate components? Reaction mechanism? Citric Acid Cycle Part Two:

Oxaloacetate Regeneration Succinyl Coenzyme A Synthetase couples hydrolysis of Coenzyme A (-Ketoglutarate Dehydrogenase: 33 kJ/mol) with GTP formation (-Ketoglutarate Dehydrogenase: 30 kJ/mol) The energetics works but what about the reaction

mechanism? Succinyl CoA-Ketoglutarate Dehydrogenase: Sythetase Generates GTP What is the Nu:-Ketoglutarate Dehydrogenase: , E, and leaving group with GTP generation?

Oxaloacetate Enzyme Regeneration from Succinate Succinate Dehydrogenase Fumerase Malate Dehydrogenase

A Color-Ketoglutarate Dehydrogenase: Coded Citric Acid Cycle Isocitrate is prochiral Succinate is a symmetric molecule

Generated products include: 2CO2 + 3NADH + 1FADH2 + GTP + CoA

Citric Acid Energetics Citric Acid Cycle Regulation Points ATP and NADH are indicators of a high energy state

ADP an indicator of a low energy state Regulatory sites include: Isocitrate dehydrogenase -Ketoglutarate Dehydrogenase: Ketoglutarate dehydrogenase Pyruvate dehydrogenase

Citric Acid Cycle is a Source for Biosynthetic Precursors Transamination Reaction

Citric Acid Cycle Intermediates: Replenished as Metabolites are Drawn Off for Biosynthesis Anapleurotic reactions lead to a replenishment

of pathway components (e.g. pyruvate carboxylase). Problems: 1, 3, 5, 7 and 9