Alanine aminotransferase (ALT) transfers an amino group from alanine to alpha ketoglutarate, forming pyruvate and glutamate. Which cofactor is essential for this reaction?

• A Tetrahydrobiopterin derived from folic acid
• B Thiamine pyrophosphate derived from vitamin B1
• C Pyridoxal phosphate derived from vitamin B6 ✓
• D Biotin derived from vitamin B7

Explanation

All aminotransferases (transaminases) require pyridoxal phosphate, the active form of vitamin B6. Its aldehyde group forms a Schiff base (aldimine) with the amino acid substrate, allowing electron withdrawal that stabilises the transition states of both transamination and decarboxylation reactions. Tetrahydrobiopterin serves hydroxylases such as phenylalanine hydroxylase, biotin serves carboxylases, and TPP serves alpha ketoacid dehydrogenase complexes.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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