Question

Transfer of an amino group from an amino acid to an alpha-keto acid is done by which enzyme?

• A. Transaminases
• B. Aminases
• C. Transketolase
• D. Decarboxylase

Hint:

Moving an amino group between an amino acid and a keto acid is transamination.

Answer 1

The Correct Option is A

The reaction in the stem describes lifting an amino group off an amino acid and placing it onto an alpha-keto acid, so that the keto acid becomes an amino acid while the original amino acid becomes a keto acid. This exchange is the definition of transamination, and the enzymes that carry it out are the transaminases, also called aminotransferases. Familiar clinical examples are ALT and AST, both of which depend on the vitamin B6 derivative pyridoxal phosphate to ferry the amino group through the catalytic cycle. None of the other options fit the description: a transketolase shuttles two-carbon fragments within the pentose phosphate pathway, a decarboxylase strips off a carboxyl group releasing carbon dioxide, and aminases is not the recognized name for this group-transfer reaction. Thus the enzyme responsible is a transaminase. \[\boxed{\text{Transaminases}}\]