During the initial stages of amino acid catabolism, the amino group is typically removed from most amino acids through a process known as transamination. This reaction involves the transfer of the amino group to an α-keto acid acceptor, most commonly α-ketoglutarate. What is the primary immediate outcome of transamination in amino acid catabolism?
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The answer
Correct answer: A. The original amino acid is converted into its corresponding α-keto acid, and α-ketoglutarate becomes glutamate.
Tested concept: Amino acid catabolism and transamination
Explanation
Transamination is the first step in the catabolism of many amino acids. In this reaction, the amino group of an amino acid is transferred to an α-keto acid (usually α-ketoglutarate), forming a new α-keto acid (from the original amino acid) and a new amino acid (glutamate from α-ketoglutarate). This process prepares the carbon skeleton of the amino acid for entry into central metabolic pathways like the citric acid cycle, and collects amino groups into glutamate for eventual excretion as urea. Distractor D1 describes oxidative deamination, which typically follows transamination for the removal of the amino group as ammonia. Distractor D2 describes protein synthesis, an anabolic process, not catabolism. Distractor D3 is incorrect because transamination itself does not directly generate ATP; rather, the resulting α-keto acids can be further metabolized to produce energy.
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