title: Modification of the active site of alkaline phosphatase by site-directed mutagenesis.
abstract: The catalytically essential amino acid in the active site of bacterial alkaline phosphatase (Ser-102) has been replaced with a cysteine by site-directed mutagenesis. The resulting thiol enzyme catalyzes the hydrolysis of a variety of phosphate monoesters. The rate-determining step of hydrolysis, however, is no longer the same for catalysis when the active protein nucleophile is changed from the hydroxyl of serine to the thiol of cysteine. Unlike the steady-state kinetics of native alkaline phosphatase, those of the mutant show sensitivity to the leaving group of the phosphate ester.
mesh_terms: D019297:2,4-Dinitrophenol / Q000031:analogs & derivatives*; D000469:Alkaline Phosphatase / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D001665:Binding Sites; D004247:DNA / Q000235:genetics; D004140:Dinitrophenols / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D007700:Kinetics; D009154:Mutation; D009596:Nitrophenols / Q000378:metabolism; D010755:Organophosphates / Q000378:metabolism; D009943:Organophosphorus Compounds / Q000378:metabolism; D010957:Plasmids
chemical_list: D004140:Dinitrophenols; D009596:Nitrophenols; D010755:Organophosphates; D009943:Organophosphorus Compounds; C047468:2,4-dinitrophenylphosphate; C008644:nitrophenylphosphate; D004247:DNA; D000469:Alkaline Phosphatase; D019297:2,4-Dinitrophenol