(01/03/11) Lecture by Kevin Ahern of Oregon State University discussing Biochemistry Basics in BB 451. See the full course at oregonstate.edu This course can be taken for credit (wherever you live) via OSU’s ecampus. For details, see ecampus.oregonstate.edu Download Metabolic Melodies at www.davincipress.com Related courses include BB 350 – oregonstate.edu BB 450 – oregonstate.edu BB 100 – oregonstate.edu Citric Acid Cycle I 1. Both oxidative decarboxylation (in higher cells) and non-oxidative decarboxylation (in yeast) use an enzymatic activity called the pyryvate dehydrogenase complex to convert pyruvate from glycolysis into acetyl-Coa for the citric acid cycle. This enzyme complex is in the mitochondrion and requires that pyruvate from the cytoplasm be transported to the mitochondrion. This complex includes the following: Pyruvate decarboxylase (your book calls it “Pyruvate Dehydrogenase Component” (E1) Dihyrolipoamide transacetylase (E2) Dihyrolipoamide dehydrogenase (E3) It also uses the coenzymes, Thiamine Pyrophosphate (TPP), Lipoamide, NAD, FAD, and Coenzyme A (also called CoASH or CoA). 2. The mechanism of the reaction catalyzed by the complex is very similar to that catalyzed by the alpha-keto-glutarate dehydrogenase complex of the Citric Acid Cycle. Both involve oxidation of alpha-keto acids. 3. In aerobic higher organisms, the reaction mechanism involves binding of pyruvate by an ionized TPP, decarboxylation, transfer to the lipoamide molecules, linkage of the …
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