BIO 205 Lecture Notes - Lecture 32: Malate Dehydrogenase, Citric Acid Cycle, Beta Oxidation
Lecture 32 Krebs Cycle
Role of TCA cycle in overall metabolic pathways
1. TCA cycle: stage 2 in aerobic metabolism
a. TCA cycle aka Krebs cycle or citric acid cycle processes the acetyl
group of Ac-CoA molecules derived from three sources which
are catabolism of glucose, beta oxidation of fatty acids, and
breakdown of some of the amino acids
b. The two carbons of acetyl group are oxidized to CO2 and
electrons are passed to NAD+ and FAD in the form of H:- and H
to produce NADH and FADH2
2. TCA cycle: central hub for amino acid catabolism
• Length of their carbon skeleton
• Linearity or branching of skeleton
• In the presence or absence of C=C bond
3. Amino acids containing C-C-C-C-C
a. Arginine, proline, histidine, glutamine, and glutamate
Overview of TCA cycle
4. Classes of rxn
a. Step 1: citrate synthase
b. Step 2: aconitase; catalyzed by a dehydratase
c. Step 3: isocitrate dehydrogenase; catalyzed by an oxidative
decarboxylase
d. Step 4: a-ketoglutarate dehydrogenase; oxidative carboxylase
e. Step 5: succinyl-CoA synthetase
f. Step 6: succinate dehydrogenase
g. Step 7: fumarase hydratase
h. Step 8: malate dehydrogenase
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