OXIDATIVE PHOSPHORYLATION. 1. Only the various oxidation reactions in glycolysis
ID: 45998 • Letter: O
Question
OXIDATIVE PHOSPHORYLATION.
1. Only the various oxidation reactions in glycolysis and the citric acid cycle, the only one that does not involve NAD+ is the succinate dehydrogenase reaction. What would deltaG be for an enzyme that oxidizes succinate with NAD+ istead of FAD? If the intramitochondrial concetration of succinate was 10-fold higher than that of fumarate, what minimum [NAD+]/[NADH] ratio in mitochondria would be needed to make this reaction exergonic at 37C?
2. If you were to determine the P/O ratio for oxidation of alpha-ketoglutarate, you would probably include some malonate in your reaction system. Why? Under these conditions, what what P/O ratio would you expect to observe?
Explanation / Answer
1) The oxidation of succinate to fumarate is catalyzed by the enzyme Succinate dehydrogenase by using FAD to NAD+ as hydrogen acceptor. This is because the free energy change is insufficent to reduce NAD+ .
for every drive with ATP synthesise produces 6 protons per an electron pair from Succinate and 10 protons from NADH.
2) Here, malonate acts as an activator in the oxidation of alpha-ketoglutarte. Thus malonate is added in the reaction system. Under such condistions, the expected P/O ratio would be low.
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