title: Binding of 125I-labeled beta-lactam antibiotics to the penicillin binding proteins of Escherichia coli.
abstract: 125I-Labeled derivatives of the beta-lactam antibiotics cephalexin, cephradine, cefaclor and 6-alpha-aminopenicillanic acid have been obtained by reacting these compounds with (125I)-Bolton-Hunter reagent. The following target proteins were found in Escherichia coli: (1) The derivatives of cephalexin, cefaclor and cephradine preferentially interact with the high molecular weight penicillin binding proteins ( PBP1a and PBP1b ); (2) The 125I- derivative of 6-alpha-aminopenicillanic acid is preferentially bound by the low molecular weight penicillin binding proteins 4 and 5/6. The iodinated derivatives showed a very high affinity of binding to their target proteins with apparent half-saturating concentrations in the nano -molar range.
mesh_terms: D000667:Ampicillin / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000378:metabolism* / Q000494:pharmacology; D001426:Bacterial Proteins; D001667:Binding, Competitive; D002268:Carboxypeptidases / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins; D006602:Hexosyltransferases; D007457:Iodine Radioisotopes; D007700:Kinetics; D002267:Muramoylpentapeptide Carboxypeptidase / Q000378:metabolism*; D046915:Penicillin-Binding Proteins; D010406:Penicillins / Q000378:metabolism*; D046928:Peptidoglycan Glycosyltransferase; D010458:Peptidyl Transferases; D046929:Serine-Type D-Ala-D-Ala Carboxypeptidase; D013329:Structure-Activity Relationship
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D007457:Iodine Radioisotopes; D046915:Penicillin-Binding Proteins; D010406:Penicillins; D000667:Ampicillin; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D046928:Peptidoglycan Glycosyltransferase; C478681:penicillin-binding protein 1B, E coli; D002268:Carboxypeptidases; D046929:Serine-Type D-Ala-D-Ala Carboxypeptidase; D002267:Muramoylpentapeptide Carboxypeptidase