An enzyme that catalyzes the transfer of an amino group from a donor molecule to a recipient molecule. The donor molecule is usu- ally an amino acid and the recipient molecule is usually an alpha-2 keto acid. Two of the best-known enzymes in this class are serum glutamic oxaloacetic transaminase (SGOT) and serum glu- tamic pyruvic transaminase (SGPT), both of which are normally found primarily in cells in the liver and heart.