03-08-2011 12:03 (11/17/10) Lecture by Kevin Ahern of Oregon State University discussing Biochemistry Basics in BB 450. See the full course at oregonstate.edu Highlights Glycolysis II 1. Reaction #9 is catalyzed by enolase and involves removal of water from 2PG to form PEP, which is a highly energetic compound. 2. Reaction #10 is the "Big Bang" of glycolysis. It is catalyzed by the enzyme pyruvate kinase and in the reaction, a substrate level phosphorylation yields ATP. Note that the Delta G zero prime is very strongly negative, helping to pull all the reactions preceding it to a large extent. The enzyme is allosterically inactivated by ATP and allosterically activated by F1,6BP. The latter activation is an example of "feed forward" activation. Pyruvate kinase is also inactivated by phosphorylation, as will be seen in glycogen metabolism. 3. The phenomenon of redox balancing is important for glycolysis. Redox balancing relates to the relative amount of NAD+ and NADH in the cell. Remember that reaction 6 is very sensitive to the ratio of NAD+/NADH. 4. Pyruvate has three separate fates, depending on conditions and the cell type. When oxygen is present, there is plenty of NAD+, so aerobic cells convert pyruvate to acetyl-CoA for oxidation in the citric acid cycle. When oxygen is absent, NAD+ levels can go down, so to prevent that from happening, pyruvate is converted to either lactate (animals) or ethanol (bacteria/yeast). Either of these last two conversions REQUIRES NADH and produces NAD+ ...
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Bite-Sized Biochemistry #22 - Glycolysis II / Carbohydrate Metabolism - Video
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