Transamination concept check: Which statement correctly describes what happens during a transamination reaction?

Introduction / Context:
Transamination reactions redistribute nitrogen among amino acids and alpha-keto acids without releasing ammonia. They are catalyzed by aminotransferases using pyridoxal phosphate (PLP) and are vital for both amino acid catabolism and biosynthesis, as well as for shuttling nitrogen into glutamate before urea formation.

Given Data / Assumptions:

• Transamination is typically reversible.
• Free ammonia is not produced directly in transamination.
• Common pairs include alanine/pyruvate and glutamate/alpha-ketoglutarate.

Concept / Approach:
Define what is transferred and between which molecules. The alpha-amino group moves from a donor amino acid to an acceptor alpha-keto acid, yielding a new amino acid and a new alpha-keto acid. This contrasts with oxidative deamination, which removes the amino group to free ammonia, and with peptide bond formation, which is a ribosomal process and not a transamination.

Step-by-Step Solution:

Verification / Alternative check:
Enzyme assays for ALT and AST, used clinically in liver function testing, directly measure transamination activities, supporting the defined chemistry.

Why Other Options Are Wrong:

• Carboxyl group transfer: not the defining feature of transamination.
• Removal of the amino group as ammonia: describes oxidative deamination.
• Polymerization into peptides: describes translation, not transamination.
• Oxygen transfer from keto acids: not a standard step in transamination.

Common Pitfalls:
Mixing up transamination with deamination or transamidation; remember that in transamination the nitrogen stays organic, simply changing partners.

Final Answer:
An amino group is transferred from an amino acid to an alpha-keto acid to form a new amino acid