title: Chemical modifications of Serratia marcescens anthranilate synthase component I.
abstract: Serratia marcescens anthranilate synthase Component I (AS I) was purified from a plasmid-containing Escherichia coli strain. Residues essential for AS I function were studied by chemical modification reactions. Phenylglyoxal and 1,2-cyclohexanedione modified 2-5 arginine residues and inactivated AS I. The substrate chorismate reduced the rate of inactivation. Analysis of inactivation data indicated that 1 arginine residue is essential for activity. Histidine residues in AS I were modified by ethoxyformic anhydride and by photooxidation. Enzyme inactivation accompanied modification of histidine residues. Inactivation was prevented by substrate. Comparison of the number of carbethoxy groups incorporated between substrate-protected and unprotected AS I indicated that 1 histidine residue is required for activity. AS I was also inactivated by bromopyruvate. Substrate retarded inactivation by bromopyruvate. A differential labeling experiment indicated that the loss of AS I activity was correlated with alkylation of 1 cysteine residue. A tryptic peptide containing the essential cysteine residue was isolated. The peptide has the amino acid sequence of Ile-Cys-Gln-Ala-Gly-Ser-Arg.
mesh_terms: D000345:Affinity Labels / Q000494:pharmacology*; D000596:Amino Acids; D000878:Anthranilate Synthase / Q000378:metabolism*; D001665:Binding Sites; D003510:Cyclohexanes / Q000494:pharmacology*; D003512:Cyclohexanones / Q000494:pharmacology*; D004047:Diethyl Pyrocarbonate / Q000494:pharmacology*; D004926:Escherichia coli / Q000201:enzymology; D005561:Formates / Q000494:pharmacology*; D007700:Kinetics; D010084:Oxidation-Reduction; D010782:Photolysis; D011485:Protein Binding; D011773:Pyruvates / Q000494:pharmacology*; D012395:Rose Bengal / Q000494:pharmacology*; D012706:Serratia marcescens / Q000201:enzymology*
chemical_list: D000345:Affinity Labels; D000596:Amino Acids; D003510:Cyclohexanes; D003512:Cyclohexanones; D005561:Formates; D011773:Pyruvates; D012395:Rose Bengal; C017092:bromopyruvate; C018031:1,2-cyclohexanedione; D000878:Anthranilate Synthase; D004047:Diethyl Pyrocarbonate