Acetyl-S-CoA Carboxylase Part 2 (Transcarboxylase)

The video explores the mechanisms of biotin carboxylase and transcarboxylase, highlighting their roles in carboxylation processes involving biotin, ATP, and bicarbonate. It details the active site interactions, proton transfers, and the formation of malonyl CoA from acetyl CoA. The interplay between enzyme subunits and the significance of malonyl CoA in fatty acid biosynthesis are also discussed.

What is the role of lysine in the biotin carboxylase mechanism?

• It interacts with bicarbonate.

• It binds to ATP.

• It stabilizes the enzyme structure.

• It acts as a nucleophile.

How does biotin interact with different domains in the enzyme complex?

• By binding to ATP.

• By changing its charge state.

• By rotating along with lysine.

• By altering its pH.

What is a key feature of the transcarboxylase mechanism?

• It is highly conserved across enzymes.

• It is unique to each enzyme.

• It requires a metal cofactor.

• It does not involve biotin.

What is the role of aspartate in the active site?

• It binds to biotin.

• It stabilizes the enzyme structure.

• It acts as a proton donor.

• It donates electrons.

What is generated during the tautomerization of acetyl CoA?

• A stable enolate.

• A protonated lysine.

• A tetrahedral intermediate.

• A nucleophilic acyl substitution.

Which carbon in malonyl CoA originates from bicarbonate?

• The central carbon.

• The terminal carbon.

• The carbonyl carbon.

• The carboxylate carbon.

What happens to the carboxyl group in malonyl CoA during fatty acid synthesis?

• It forms a new bond with acetyl CoA.

• It is incorporated into the fatty acid.

• It is lost as carbon dioxide.

• It is converted to a hydroxyl group.

What is the primary function of malonyl CoA in fatty acid biosynthesis?

• To serve as a building block.

• To inhibit enzyme activity.

• To transport fatty acids.

• To act as an energy source.

How does enzyme conformation change affect biotin's interaction with enzyme domains?

• It rotates biotin between domains.

• It modifies the enzyme's size.

• It alters the enzyme's pH.

• It changes the enzyme's charge.

What is the role of fatty acid synthase in relation to malonyl CoA?

• It uses malonyl CoA to synthesize fatty acids.

• It breaks down malonyl CoA.

• It stores malonyl CoA for later use.

• It converts malonyl CoA to ATP.