Kinetic Study of Interaction between Brl 42715, Beta-Lactamases, and D-Alanyl-D-Alanine Peptidases

in Antimicrobial Agents and Chemotherapy (1995), 39(1), 227-31

A detailed kinetic study of the interactions between BRL 42715, a beta-lactamase-inhibiting penem, and various beta-lactamases (EC 3.5.2.6) and D-alanyl-D-alanine peptidases (DD-peptidases, EC 3.4.16.4 ... [more ▼]

A detailed kinetic study of the interactions between BRL 42715, a beta-lactamase-inhibiting penem, and various beta-lactamases (EC 3.5.2.6) and D-alanyl-D-alanine peptidases (DD-peptidases, EC 3.4.16.4) is presented. The compound was a very efficient inactivator of all active-site serine beta-lactamases but was hydrolyzed by the class B, Zn(2+)-containing enzymes, with very different kcat values. Inactivation of the Streptomyces sp. strain R61 extracellular DD-peptidase was not observed, and the Actinomadura sp. strain R39 DD-peptidase exhibited a low level of sensitivity to the compound. [less ▲]

Kinetic properties of the Bacillus licheniformis Penicillin-binding proteins

in Biochemical Journal (1995), 309

A common system controls the induction of very different genes. The class-A beta-lactamase of Proteus vulgaris and the enterobacterial class-C beta-lactamase.

in European Journal of Biochemistry (1994), 226(1), 149-57

Among the Enterobacteriaceae, Proteus vulgaris is exceptional in the inducible production of a 29-kDa beta-lactamase (cefuroximase) with an unusually high activity towards the beta-lactamase-stable ... [more ▼]

Among the Enterobacteriaceae, Proteus vulgaris is exceptional in the inducible production of a 29-kDa beta-lactamase (cefuroximase) with an unusually high activity towards the beta-lactamase-stable oximino-cephalosporins (e.g. cefuroxime and cefotaxime). Sequencing of the corresponding gene, cumA, showed that the derived CumA beta-lactamase belonged to the molecular class A. The structural gene was under the direct control of gene cumR, which was transcribed backwards and whose initiation codon was 165 bp away from that of the beta-lactamase gene. This resembled the arrangement of structural and regulator genes ampC and ampR of the 39-kDa molecular-class-C beta-lactamase AmpC present in many enterobacteria. Moreover, cloned genes ampD and ampG for negative modulation and signal transduction of AmpC beta-lactamase induction, respectively, were also able to restore constitutively CumA overproducing and non-inducible P. vulgaris mutants to the inducible, wild-type phenotype. The results indicate that controls of the induction phenomena are equivalent for the CumA and AmpC beta-lactamase. Very different structural genes can thus be under the control of identical systems. [less ▲]

Synthesis, purification and kinetic properties of fluorescein-labelled penicillins

in Biochemical Journal (1994), 300

Acyltransferase activities of the high-molecular-mass essential penicillin-binding proteins

in Biochemical Journal (1991), 279(Part 2), 601-604

The high-molecular-mass penicillin-binding proteins (HMM-PBPs), present in the cytoplasmic membranes of all eubacteria, are involved in important physiological events such as cell elongation, septation or ... [more ▼]

The high-molecular-mass penicillin-binding proteins (HMM-PBPs), present in the cytoplasmic membranes of all eubacteria, are involved in important physiological events such as cell elongation, septation or shape determination. Up to now it has, however, been very difficult or impossible to study the catalytic properties of the HMM-PBPs in vitro. With simple substrates, we could demonstrate that several of these proteins could catalyse the hydrolysis of some thioesters or the transfer of their acyl moiety on the amino group of a suitable acceptor nucleophile. Many of the acyl-donor substrates were hippuric acid or benzoyl-D-alanine derivatives, and their spectroscopic properties enabled a direct monitoring of the enzymic reaction. In their presence, the binding of radioactive penicillin to the PBPs was also inhibited. [less ▲]

Chromosome-encoded beta-lactamases of Citrobacter diversus. Interaction with beta-iodopenicillanate and labelling of the active site.

in Biochemical Journal (1988), 254(3), 891-3

Both forms of the chromosome-encoded beta-lactamase of Citrobacter diversus react with beta-iodopenicillanate at a rate characteristic of class A beta-lactamases. The active site of form I was labelled ... [more ▼]

Both forms of the chromosome-encoded beta-lactamase of Citrobacter diversus react with beta-iodopenicillanate at a rate characteristic of class A beta-lactamases. The active site of form I was labelled with the same reagent. The sequence of the peptide obtained after trypsin hydrolysis is identical with that of a peptide obtained in a similar manner from the chromosome-encoded beta-lactamase of Klebsiella pneumoniae. [less ▲]

Properties of a class C beta-lactamase from Serratia marcescens.

in Biochemical Journal (1986), 239(3), 581-6

A beta-lactamase produced by a penicillin-resistant strain of Serratia marcescens was isolated and purified. The kcat. value for benzylpenicillin was about 5% of that observed for the best cephalosporin ... [more ▼]

A beta-lactamase produced by a penicillin-resistant strain of Serratia marcescens was isolated and purified. The kcat. value for benzylpenicillin was about 5% of that observed for the best cephalosporin substrates. However, the low Km of the penam resulted in a high catalytic efficiency (kcat./Km) and the classification of the enzyme as a cephalosporinase might not be completely justified. It also exhibited a low but measurable activity against cefotaxime, cefuroxime, cefoxitin and moxalactam. Substrate-induced inactivation was observed both with a very good (cephalothin) or a very bad (moxalactam) substrate. The active site was labelled by beta-iodopenicillanate. Trypsin digestion produced a 19-residue active-site peptide whose sequence clearly allowed the classification of the enzyme as a class C beta-lactamase. [less ▲]