Which enzyme catalyzes the transfer of amino groups causing the interconversion of amino acids and alpha-oxoacids?

• A. Amylase
• B. Aspartate transaminase
• C. Alkaline phosphatase
• D. Lactate dehydrogenase

Answer: (B)

Transaminases carry out transamination: they move an amino group from an amino acid to a keto acid, creating a new amino acid and a new alpha-keto acid. This is how amino acids and alpha-oxoacids interconvert, a key process in amino acid metabolism. The enzyme that best fits this description among the options is aspartate transaminase, a classic aminotransferase that transfers the amino group from aspartate to α-ketoglutarate to form oxaloacetate and glutamate. This reaction relies on pyridoxal phosphate as a cofactor and is reversible, reflecting the dynamic nature of amino acid and keto acid pools in the body. The other enzymes perform different roles: one digests starch (amylase), another removes phosphate groups (alkaline phosphatase), and another uses redox chemistry to interconvert lactate and pyruvate (lactate dehydrogenase).