title: Methionine 500, the site of covalent attachment of an active site-directed reagent of beta-galactosidase.
abstract: The site of attachment to beta-galactosidase of the active site-directed inhibitor, beta-D-galactopyranosylmethyl p-nitrophenyl triazene, was determined. When the enzyme is completely inactivated, 1 mol of the galactopyranosylmethyl group is bound per mol of monomer with retention of the tetrameric structure. After reaction with the [14C]methyl reagent, labeled peptides were isolated and analyzed. The radioactive label was found to be covalently bound to methionine residue 500.
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D005696:Galactosidases / Q000378:metabolism; D005697:Galactosides; D008715:Methionine; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D005697:Galactosides; D008715:Methionine; D005696:Galactosidases; D001616:beta-Galactosidase