Which enzyme is responsible for the conversion of homocysteine to methionine in the methionine cycle, and its deficiency is associated with hyperhomocysteinemia?

A Methionine synthase ✓
B Cystathionine beta-synthase
C Betaine-homocysteine methyltransferase
D Homocysteine methyltransferase

Explanation

Methionine synthase is the enzyme responsible for the conversion of homocysteine to methionine in the methionine cycle, and its deficiency can lead to hyperhomocysteinemia.

Source

Journal of Clinical Investigation
Enzymes in Disease Biochemistry Amino Acid Metabolism Hard MEDICAL Confidence: high