Methionine 500, the site of covalent attachment of an active site-directed reagent of beta-galactosidase
Fowler, A.V.; Zabin, I.; Sinnott, M.L.; Zabin, I.
Journal of Biological Chemistry 253(15): 5283-5285
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.