Question

Which enzyme–substrate pair is CORRECT?

Group of answer choices

- methylmalonyl CoA mutase – 3-hydroxy-3-methyl-glutaryl CoA

- acyl CoA synthetase – acetyl CoA

- thiolase – 3-ketoacyl CoA

- hydroxymethylglutaryl CoA synthase – L-methylmalonyl CoA

- cis-Δ³-enoyl CoA isomerase – trans-Δ³-enoyl CoA

Answer 1

Answer- thiolase- 3-ketoacyl CoA

Explanation- thiolse is last enzyme in beta oxidation which converts substrate 3-ketoacyl CoA to acyl CoA and acetyl-CoA. So that correct enzyme substrate pair is thiolase - 3-ketoacyl CoA.

Wrong pairs are-

• Methylamalonyl-CoA mutase - 3-hydroxy-3- methyl -glutaryl CoA = methylmalonyl-CoA mutase is member of isomerase family carry out isomerization of substrate methylmalonyl-CoA to succinyl-CoA. So that 3-hydroxy-3- methyl -glutaryl CoA is not substrate of methylmalonyl-CoA mutase.

• acyl CoA synthetase- acetyl-CoA = acyl CoA synthetase carry out activation of fatty acid by forming thioester linkage between fatty acid group and thiol group of CoA and produces fatty acyl-CoA. So that acyl CoA synthetase has substrate fatty acid but not acetyl CoA.

• hydroxymethylglutaryl CoA synthase - L- methylmalonyl CoA = hydroxymethylglutaryl CoA synthase (HMG-CoA synthase) converts acetoacetyl-CoA to hydroxymethylglutaryl CoA (HMG CoA). L-methylmalonyl CoA is not substrate of HMG-CoA synthase.

• cis- 3-enoyl CoA isomerase - trans -3-enoyl CoA -= cis 3-enoyl CoA isomerase converts substrate cis 3-enoyl CoA to trans 2-enoyl CoA. So that trans 3-enoyl CoA is not substrate of this enzyme.