amino-acid metabolism metabolism of amino-acids, a group of organic compound containing an amino group (NH2), a carboxylic acid group (COOH), and any of various side groups, especially any of the 20 compounds that have the basic formula NH2CHRCOOH, and that link together by peptide bonds to form proteins or that function as chemical messengers and as intermediates in metabolism. Amino-acids are the precursors of many molecules such as purines, pyrimidines, histamines, adrenaline and melanin. GO:0006520 UPa:UPA00401 pathway AA metabolism metabolic intermediate metabolism