Question

Describe the general role of an a-keto acid in a transamination reaction and the ultimate goal that makes a transamination reaction necessary.

So my question is what is the overall goal because I understand that transmination reactions basically transfer a amino group to a alpha ketoacid like oxaloacetate and alpha ketoglutarate. This is done to produce non essential amino acids. But why is this reaction done in the first place if non essential amino acids are produced especially in the citric acid cycle.

Answer 1

A specific example is the transamination of alanine to make pyruvic acid and glutamic acid. This process is an important step by which amino acids can be synthesized by the organism. The product of transamination reactions depends on the availability of alpha-keto acids. The products usually are either alanine, aspartate or glutamate, since their corresponding alpha-keto acids are produced through metabolism of fuels through Citric acid cycle.

Now coming to your last question only the carbon skeletons of many non-essential amino acids are made from citric acid cycle intermediates like oxaloacetate which forms aspartate and asparagine; and alpha-ketoglutarate which forms glutamine, proline, and arginine. Thus Citric acid cycle provides only the carbon skeleton and the rest work is done by the transamination process by actually converting them to non-essential amino acids.