Which vitamin-derived cofactor is required by aminotransferases (transaminases, such as AST and ALT) to transfer amino groups between amino acids and alpha-keto acids?
Answer and explanation
Correct answer: D. Pyridoxal 5'-phosphate (PLP from Vitamin B6)
All transamination reactions use pyridoxal 5'-phosphate (PLP, the active coenzyme form of vitamin B6). PLP forms an intermediate Schiff base (aldimine) with the substrate amino acid, accepting the amino group to become pyridoxamine phosphate (PMP), which then transfers the amino group to an alpha-keto acid to generate a new amino acid.
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