title: A specific cephalosporin-binding protein of Citrobacter freundii.
abstract: 1. A cephalosporin-binding protein obtained from a strain of Citrobacter freundii was purified to the extent of a single band in analytical and sodium dodecyl sulfate-containing disc electrophoresis. 2. The molecular weight determined by disc electrophoresis was 53 000. 3. The binding protein did not show any beta-lactamase activity at substrate concentrations examined: 6 mM to 100 muM of penicillins and 12 mM to 100 muM of cephalosporins. 4. In gel filtration, [14C]benzylpenicillin was found not to bind to the binding protein. 5. In fluorescence titration, all cephalosporins tested quenched the fluorescence. Association constants of cephalosporins were in the range of 0.8-12-103 M-1, and one binding site was calculated for all cephalosporins tested.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D001426:Bacterial Proteins / Q000032:analysis* / Q000378:metabolism; D001665:Binding Sites; D001667:Binding, Competitive; D002510:Cephalosporinase / Q000378:metabolism; D002511:Cephalosporins / Q000378:metabolism*; D002954:Citrobacter / Q000378:metabolism*; D004755:Enterobacteriaceae / Q000378:metabolism*; D007700:Kinetics; D008970:Molecular Weight; D010400:Penicillin G / Q000378:metabolism; D011485:Protein Binding; D011955:Receptors, Drug; D013050:Spectrometry, Fluorescence
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; D002511:Cephalosporins; D011955:Receptors, Drug; D002510:Cephalosporinase; D010400:Penicillin G