Biochemistry 2280A Study Guide - Midterm Guide: Enzyme Inhibitor, Insulin, Nicotinamide
11 Oct 2017
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The citric acid cycle: under aerobic conditions, pyruvate produced by glycolysis is transported into mitochondria, where it is oxidized to form co2. Mitochondrial structure: mitochondrion: organelle with 2 membranes, outer membrane: has many pores embedded, freely permeable to most solutes of low molecular weight (up to 5000 kda) Mitochondrial respiration: convert pyruvate and o2 into co2 and h2o: respiration, o2 we inhale in physiological respiration is used primarily as the final electron acceptor for mitochondrial respiration. Oxidation of pyruvate to co2 in mitochondria: 2 stages, 1. Decarboxylation of pyruvate and addition of coenzyme a to form acetyl-coa: 2. Irreversible: only way mammals produce acetyl-coa from carbohydrates, pyruvate dehydrogenase complex is an assembly of 3 enzymes, 60 polypeptide chains in all. Inhibited by its products, acetyl-coa and nadh, which compete with coa and nad+ respectively: acetyl-coa and nadh also promote phosphorylation of a serine residue on the enzyme complex. > inactivates the complex: pyruvate inhibits this phosphorylation, increasing enzyme activity.
