Question

The pyruvate dehydrogenase is allosterically inhibited by all of the following except?

a) low adp/atp ratios
b) low amp / atp ratios
c) low nad+/ nadh ratios
d) low coa-sh/ acetyl-coa ratios
e) low acetyl coa / coa-sh ratios

Answer 1

e) low acetyl-CoA/CoA-sh ratios

Step-by-step explanation:

The enzyme pyruvate dehydrogenase is allosterically inhibited by a high concentration of some of the products of the reaction it catalyzes: NADH and Acetyl-CoA, and ATP (since its a enzyme involved in the cellular respiration, a metabolic process that converts organic molecules into energy/ATP).

So, if you have a low ratio of acetyl-CoA/CoA-sh it means you have a more of CoA-sh than acetyl-CoA, therefore wouldn't allosterically inhibited the enzyme.

Answer 2

The correct answer is option e) "low acetyl coa / coa-sh ratios".

Step-by-step explanation:

Allosteric inhibition, also known as negative allosteric modulation, occurs when a ligand decreases one enzyme's affinity to its substrate by binding to a site different from the active site. One classic example of allosteric inhibition takes place in pyruvate dehydrogenase, an enzyme that converts pyruvate into acetyl-CoA by a process called pyruvate decarboxylation. Pyruvate dehydrogenase is inhibited by the end products of the reactions that it catalyzes to regulate its activity. Therefore, a low acetyl coa / coa-sh ratios would not inhibited pyruvate dehydrogenase, on the contrary, a high concentration of acetyl coa would inhibit its activity.