organic group modified amino-acid residue An organic group that results from covalent modification or chemical alteration to the side chain or backbone atoms of an amino acid residue or derivative thereof, where such alteration maintains the integrity of the amino acid chain containing the residue. Category=external. Note: This entity is distinct from MOD:00000 "protein modification" in that the latter includes proteolytic cleavages. [PRO:DAN, PRO:JSG] PR:000025513 modified amino acid chain residue modified protein residue protein peptidyl modified amino-acid residue non-peptidyl modified amino-acid residue