Definition: Molecular subunits composing proteins. It is a class of 20 molecules that are combined to form proteins in living things. The sequence of amino acids in a protein and hence protein function are determined by the genetic code.
Amino acids contain a basic amino (NH2) group, an acidic carboxyl (COOH) group and a side chain (R - of a number of different kinds) attached to an alpha carbon atom.
See also
Links
aminoacids metabolism at Wayne
References
Lobanov AV, Kryukov GV, Hatfield DL, Gladyshev VN. Is there a twenty third amino acid in the genetic code? Trends Genet. 2006 Jul;22(7):357-60. PMID: 16713651