Transamination:

Prior to the metabolism of their carbon skeletons into a major metabolic intermediate, the α-amino set of the amino acid has first to be erased through a procedure called transamination.   In this procedure the α-amino group of most amino

Figure:  Biosynthetic families of amino acids.

acids is transferred to  α -ketoglutarate  to form glutamate and the subsequent α-keto acid:

 α-amino α- amino acid+ α -ketoglutarate  ↔ α-keto acid+ glutamate

The enzymes which catalyze these reactions are known as transaminases aminotransferases and in mammals are start predominantly in the liver.  For instance, aspartate transaminase catalyzes the transfer of the amino group of aspartate to α-ketoglutarate although alanine transaminase catalyzes the transfer of the amino group of alanine to α-ketoglutarate.