Constitutive Inorganic Pyrophosphatase of Escherichia coli VI. INACTIVATION BY CHEMICAL MODIFICATION OF LYSINE RESIDUES

摘要: Abstract Escherichia coli pyrophosphatase was inactivated by reaction with reagents which modify the e-amino groups of lysine residues. These included 2,4,6-trinitrobenzene sulfonic acid (TNBS), potassium cyanate, diazonium-1H-tetrazole, and anhydrides maleic succinic acids. The enzyme unaffected diisopropyl phosphorofluoridate, N-acetylimidazole, sulfhydryl (N-ethylmaleimide p-hydroxymercuribenzoate). inactivation lysine-modifying agents followed pseudo first-order kinetics respect to sites. Detailed analyses TNBS indicated that interaction 1 molecule an residue led a second-order rate constant 86 m-1 min-1 in 0.5 m NaHCO3, pH 8.5. Inorganic pyrophosphate, competitive inhibitor absence divalent cation, partially protected against inactivation, but kinetic this effect showed could react enzyme-pyrophosphate complex, although lower (52 min-1). results can be interpreted either terms active site modification or on apart from whose integrity is essential for function enzyme.