Lecture+18+Citric+acid+cycle notes

Endproduct inhibition not allosteric products have

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Unformatted text preview: CoA Two mechanisms: 1. Endproduct inhibition (not allosteric) Products have high affinity for active site(s) At higher [product], active site occupied, inhibiting forward rxn 2.  Phosphorylation NADH, acetyl CoA, activate a kinase that inactivate the enzyme 19 Oxaloacetate + 2 CoASH + 2 NADH + FADH2 + 2 H+ 20 The glyoxylate and citric acid cycles Regulation: low [AMP] (high energy charge) activates a kinase that phosphorylates and inactivates isocitrate dehydrogenase, blocking the citric acid cycle and shunting into the glyoxylate cycle. Blocked when energy charge high Important points from today’s lecture Citric acid cycle Intermediates needed in catalytic amounts They get used up in biosynthetic rxns Need anapleurotic rxns Cannot convert fats to carbohydrates Regulated mainly by availability of acetyl CoA and O2 Used it to discuss isotope labeling and prochirality Pyruvate dehydrogenase example of a multienzyme complex regulated by feedback inhibition 21 when energy charge is high you don't need citric acid cycle 22...
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