Catabolism of amino acids

The catabolic breakdown of amino acids yields compounds that act as intermediates in the citric acid cycle, whilst the anabolic formation of amino acids uses citric cycle intermediates as precursors.
The catabolism and anabolism of amino acids are linked but are not the exact reverse reactions of one another. For example transamination plays an important role in both processes, and they don’t involve the same group of enzymes.

A glucogenic amino acid produces pyruvate or oxaloacetate when broken down. Oxaloacetate is the starting point for the production of glucose via gluconeogenesis.
A ketogenic amino acid will produce acetyl-CoA or actoacetyl-CoA when broken down, which will lead to the production of ketone bodies.
Amino acids that have been converted to acetyl-CoA and acetoacteyl-CoA are used as intermediates in the citric acid cycle, but mammals cannot use them in glucose synthesis. This fact is the distinction between glucogenic and ketogenic amino acids .