Question

Biotin is a B-vitamin that is required for pyruvate carboxylase and acetyl-CoA carboxylase to function properly

a) In a biotin deficiency, would you expect β-hydroxybutyrate concentration in blood to increase, decrease, or stay the same compared to a biotin sufficient control?

b) How is pyruvate carboxylase involved in this effect on [BHB]?

c) How is acetyl-CoA carboxylase involved in this effect on [BHB]?

Answer 1

Insulin play a major role here. .

If insulin is less , lipase degrade fatty acids and form acetyl coA and enters TCA and will combine with oxaloacetate but as insulin is less glucose molecule do not catabolised so pyruvate does not formed and hence no formation of oxaloacetae

oxaloacetate will be deficient as it will be preferentially shifted into the gluconeogenesis pathway .The oxaloacetate deficiency, when combined with overproduction of acetyl-CoA, will shift the further metabolism of acetyl-CoA towards ketone body formation (BHA) .

Biotin catalyles the acetylcoA to acetoacetate and pyruavte to acetoacetate but here neither conversion occur so, it's deficieny nor overdose can cause anything.

2 acetyl-CoA molecules must combine to form 1 molecule of acetoacetic acid (AcAa) and the acetoacetic acid must be carried in the blood to peripheral cells where it can be utilized as an energy source . Acetoacetic acid is also converted directly to β-hydroxybutyric acid (BHA) and acetone, both of which are ketone bodies.

Biotin concerts pyruvate to acetoacetic acid ( in presence on pyruvate carboxylase) and acetyl coA to malonyl to acetoacetate ( in presence of acetyl carboxylase).

Acetoacetate converts to BHA ( ketone body) .