title: Penem derivatives: beta-lactamase stability and affinity for penicillin-binding proteins in Escherichia coli.
abstract: Penem derivatives, a new group of beta-lactam antibiotics with potent activities against a wide range of bacteria, including Pseudomonas aeruginosa, were tested for their stability against hydrolysis by beta-lactamases purified from clinical isolates of Morganella morganii. Proteus vulgaris, and Escherichia coli and by a penicillinase from Bacillus cereus. Penems having 6 alpha substituents, such as hydroxyethyl, hydroxymethyl, and ethyl groups, were very stable against hydrolysis by each of the enzymes. Penems having no 6 alpha substituents were easily hydrolyzed by P. vulgaris and E. coli enzymes, whereas they were rather stable against hydrolysis by M. morganii and B. cereus enzymes, a typical cephalosporinase and penicillinase, respectively. Affinity of the penems for E. coli penicillin-binding proteins (PBPs) was also tested. beta-Lactamase-stable penems having a 6 alpha-hydroxyethyl group showed high affinity for PBP-4, -5, and -6 as well as for PBP-1A, -1Bs, and -2. However, the penems having no 6 alpha substituents showed a far lower affinity for PBP-4, -5, and -6 than that shown by the corresponding 6 alpha-hydroxyethyl penems. Among the penems tested, affinity for PBP-4, -5, and -6 was closely related to their beta-lactamase stability, as was the case among cephamycins and cephalosporins. Effects of the penems on the morphology of a strain of E. coli are also described.
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology*; D001426:Bacterial Proteins; D002352:Carrier Proteins / Q000378:metabolism*; D055598:Chemical Phenomena; D002621:Chemistry; D004355:Drug Stability; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism*; D006602:Hexosyltransferases; D006868:Hydrolysis; D002267:Muramoylpentapeptide Carboxypeptidase; D046915:Penicillin-Binding Proteins; D010458:Peptidyl Transferases; D011485:Protein Binding; D013379:Substrate Specificity; D001618:beta-Lactamases / Q000378:metabolism*; D047090:beta-Lactams / Q000378:metabolism / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D002352:Carrier Proteins; D046915:Penicillin-Binding Proteins; D047090:beta-Lactams; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D002267:Muramoylpentapeptide Carboxypeptidase; D001618:beta-Lactamases