Elimination of a good leaving group from the 3'-position of a cephalosporin need not be concerted with .beta.-lactam ring opening: TEM-2 .beta.-lactamase-catalyzed hydrolysis of pyridine-2-azo-4'-(N',N'-dimethylaniline) cephalosporin (PADAC) and of cephaloridine

1984 ◽  
Vol 106 (5) ◽  
pp. 1489-1490 ◽  
Author(s):  
W. Stephen Faraci ◽  
R. F. Pratt
Keyword(s):  
Ring Opening ◽  
Beta Lactamase ◽  
Beta Lactam ◽  
Leaving Group ◽  
Lactam Ring ◽  
Hydrolysis Of

Characteristics of Aerobacter beta-lactamase

1968 ◽  
Vol 14 (2) ◽  
pp. 139-145 ◽  
Author(s):  
M. Goldner ◽  
D. G. Glass ◽  
P. C. Fleming
Keyword(s):  
Reaction Rates ◽  
Penicillin G ◽  
Cephalosporin C ◽  
Beta Lactamase ◽  
Beta Lactam ◽  
Lactam Ring ◽  
Rate Of Hydrolysis ◽  
High Concentrations ◽  
Hydrolysis Of ◽  
Pseudomonas Pyocyanea

In this investigation, Aerobacter cloacae is shown to inactivate cephalosporin by hydrolysis of its beta-lactam ring. This was demonstrated by iodine absorption and infrared absorption spectra.The values of the Michaelis constant obtained with cephalosporin C and deacetyl cephalosporin C indicate a great affinity of the Aerobacter's beta-lactamase for its substrate. The enzyme was most active at pH 7.0 and 37 C. Aqueous washings of the Aerobacter cells were a potent source of enzyme.The beta-lactamase of A. cloacae was active on both cephalosporin and penicillin. A higher rate of hydrolysis was observed with cephalosporin C and deacetyl cephalosporin C than with cephalothin and cephaloridine. The ratio of reaction rates on cephalosporin C to that on penicillin G was consistently of the order of 100 to 1. The activity on V, N, and especially the semisynthetic penicillins was also low.The A. cloacae enzyme was easily demonstrable in large amount without added inducer. By contrast, the activity of the beta-lactamase from Pseudomonas pyocyanea cannot be detected unless high concentrations of inducer are used.

scholarly journals Inhibition of class C β-lactamases by (1′R,6R)-6-(1′-hydroxy)benzylpenicillanic acid SS-dioxide

1985 ◽  
Vol 225 (2) ◽  
pp. 435-439 ◽  
Author(s):  
G C Knight ◽  
S G Waley
Keyword(s):  
Side Chain ◽  
Beta Lactamase ◽  
Beta Lactam ◽  
Beta Lactamases ◽  
Beta Lactam Antibiotics ◽  
Lactam Ring ◽  
Class C ◽  
Hydrolysis Of

beta-Lactamases, enzymes that catalyse the hydrolysis of the beta-lactam ring in beta-lactam antibiotics, are divided into three classes, A, B and C, on the basis of the structures so far determined. There are relatively few effective inhibitors of class C beta-lactamases. A beta-lactam sulphone with a hydroxybenzyl side chain, namely (1′R,6R)-6-(1′-hydroxy)benzylpenicillanic acid SS-dioxide (I), has now been studied. The sulphone is a good mechanism-based inhibitor of class C beta-lactamases. At pH8, the inhibition of a Pseudomonas beta-lactamase is irreversible, and proceeds at a rate that is about one-tenth the rate of concurrent hydrolysis. The labelled enzyme has enhanced u.v. absorption and is probably an enamine. At a lower pH, however, inhibition is transitory.

scholarly journals PREVALENCE OF CEPHALOSPORIN-RESISTANT GRAM-NEGATIVE BACILLI FROM CLINICAL SAMPLES

2016 ◽  
pp. 176
Author(s):  
Kavi Aniis ◽  
Rajamanikandan Kcp ◽  
Arvind Prasanth D
Keyword(s):  
Clinical Samples ◽  
Beta Lactamase ◽  
Bacterial Isolates ◽  
Beta Lactam ◽  
Gram Negative ◽  
Beta Lactamases ◽  
Extended Spectrum Beta Lactamase ◽  
E Coli ◽  
Lactam Ring ◽  
Esbl Producers

<p>ABSTRACT<br />Objective: Beta-lactams are the group of antibiotics that contain a ring called as “beta-lactam ring,” which is responsible for the antibacterial activity.<br />The presence of resistance among Gram-negative organisms is due to the production of beta-lactamases enzymes that hydrolysis the beta-lactam ring<br />thereby conferring resistance to the organism. This study is undertaken to determine the prevalence of extended-spectrum beta-lactamase (ESBL)<br />producing Gram-negative organism from clinical samples.<br />Methods: A total of 112 clinical samples were taken for this study. The combined disc synergistic test (CDST) was used for the phenotypic detection<br />of ESBL producers from the clinical samples. The genotypic identification of ESBL producers was carried out by alkaline lysis method by isolation of<br />plasmid DNA.<br />Result: A total of 87 bacterial isolates were isolated and identified. Among them, Klebsiella (41%) was the predominant organism followed by<br />Escherichia coli (33%), Proteus (10%), Pseudomonas (10%), and Serratia (6%). Among the various bacterial isolates, Klebsiella showed a higher<br />percentage of resistance. The CDST showed that 8 isolates of Klebsiella, 3 isolates of E. coli, and 1 isolate of Pseudomonas were found to be ESBL<br />producers. The genotypic confirmation showed that the two bacterial isolates, namely, Klebsiella and E. coli were found to possess temoniera (TEM)<br />gene which was the 400-500 bp conferring resistance to the antibiotics.<br />Conclusion: The results of this study suggest that early detection of ESBL producing Gram-negative organism is a very important step in planning the<br />therapy of patient in Hospitals. CDST continues to be a good indicator in the detection of ESBL producers.<br />Keywords: Beta-lactamases, Gram-negative bacilli, Extended-spectrum beta-lactamase, Resistance, Combined disc synergistic test.</p><p> </p>

scholarly journals A metallo-beta-lactamase with both beta-lactamase and ribonuclease activity is linked with traduction in giant viruses

2019 ◽  
Author(s):  
Philippe Colson ◽  
Lucile Pinault ◽  
Said Azza ◽  
Nicholas Armstrong ◽  
Eric Chabriere ◽  
...  
Keyword(s):  
Acanthamoeba Castellanii ◽  
Deep Ocean ◽  
Penicillin G ◽  
Beta Lactamase ◽  
Beta Lactam ◽  
Strong Activity ◽  
Beta Lactam Antibiotics ◽  
Double Stranded Dna ◽  
Giant Viruses ◽  
Hydrolysis Of

ABSTRACTEnzymatic proteins with a metallo-beta-lactamase (MBL) fold have been essentially studied in bacteria for their activity on beta-lactam antibiotics. However, the MBL fold is ancient and highly conserved, and these proteins are capable of cleaving a broad range of substrates. It has recently been shown that MBLs are present in a wide array of cellular organisms, including eukaryotes and archaea. We show here that Tupanvirus deep ocean, a giant virus, also encodes a protein with a MBL fold. Phylogeny showed its clustering with transfer ribonucleases (RNases) and the presence of orthologs in other giant viruses, mainly those harboring the largest sets of translation components. In addition, it suggests an ancient origin for these genes and a transfer between giant viruses and Acanthamoeba spp., a host of many giant viruses. Biologically, after its expression in Escherichia coli, the tupanvirus protein was found to hydrolyse nitrocefin, a chromogenic beta-lactam. We also observed an hydrolysis of penicillin G (10 μg/mL) and detected the metabolite of penicillin G hydrolysis, benzylpenilloic acid. This was inhibited by sulbactam, a beta-lactamase inhibitor. In addition, we tested the degradation of single-stranded DNA, double-stranded DNA, and RNAs, and observed a strong activity on RNAs from seven bacteria with G+C varying from 42% to 67%, and from Acanthamoeba castellanii, the tupanvirus host. This was not inhibited by sulbactam or ceftriaxone. RNase activity was estimated to be 0.45±0.15 mU/mg using a fluorescence-based assay. Our results still broaden the range of hosts of MBL fold proteins and demonstrate that such protein can have dual beta-lactamase/nuclease activities. We suggest that they should be annotated according to this finding to avoid further confusion.

scholarly journals Substrate-induced inactivation of the OXA2 β-lactamase

1993 ◽  
Vol 295 (3) ◽  
pp. 871-878 ◽  
Author(s):  
P Ledent ◽  
J M Frère
Keyword(s):  
Competitive Inhibition ◽  
Hydrolysis Product ◽  
Beta Lactamase ◽  
Beta Lactam ◽  
Hydrolysis Time ◽  
Beta Lactam Antibiotics ◽  
Class D ◽  
Time Courses ◽  
Burst Kinetics ◽  
Hydrolysis Of

The hydrolysis time courses of 22 beta-lactam antibiotics by the class D OXA2 beta-lactamase were studied. Among these, only three appeared to correspond to the integrated Henri-Michaelis equation. ‘Burst’ kinetics, implying branched pathways, were observed with most penicillins, cephalosporins and with flomoxef and imipenem. Kinetic parameters characteristic of the different phases of the hydrolysis were determined for some substrates. Mechanisms generally accepted to explain such reversible partial inactivations involving branches at either the free enzyme or the acyl-enzyme were inadequate to explain the enzyme behaviour. The hydrolysis of imipenem was characterized by the occurrence of two ‘bursts’, and that of nitrocefin by a partial substrate-induced inactivation complicated by a competitive inhibition by the hydrolysis product.

scholarly journals The inhibition of staphylococcal β-lactamase by clavulanic acid

1979 ◽  
Vol 179 (1) ◽  
pp. 67-76 ◽  
Author(s):  
C Reading ◽  
P Hepburn
Keyword(s):  
Enzyme Activity ◽  
Clavulanic Acid ◽  
Cell Extract ◽  
Beta Lactam ◽  
Beta Lactamases ◽  
First Order ◽  
Lactam Ring ◽  
Covalent Intermediate ◽  
Hydrolysis Of ◽  
Inhibited Enzyme

Clavulanic acid inhibited both the extracellular and cell-extract beta-lactamases of the four Staphylococcus aureus strains tested. The inhibition of S. aureus Russell cell-extract enzyme appeared to be active-site-directed and proceeded in a first-order fashion consistent with the formation of a covalent intermediate. Inhibited enzyme free of excess clavulanic acid was shown to regenerate enzyme activity slowly at pH 7.0, but the rate of reactivation increased at acid pH. When the enzyme was incubated with excess clavulanic acid complete inhibition was rapidly obtained, during further incubation clavulanic acid was shown to disappear slowly and complete loss of clavulanic acid from the reaction mixture coincided with the onset of the return of enzyme activity. A reactive enamine resulting from enzymic hydrolysis of the beta-lactam ring of clavulanic acid has been proposed as a possible intermediate in the inhibitory mechanism.

scholarly journals A thiono-β-lactam substrate for the β-lactamase II of Bacillus cereus. Evidence for direct interaction between the essential metal ion and substrate

1989 ◽  
Vol 258 (3) ◽  
pp. 765-768 ◽  
Author(s):  
B P Murphy ◽  
R F Pratt
Keyword(s):  
Bacillus Cereus ◽  
Active Site ◽  
Metal Ion ◽  
Direct Interaction ◽  
Beta Lactamase ◽  
Beta Lactam ◽  
Enzyme Active Site ◽  
Lactam Carbonyl ◽  
Beta Lactamase Ii ◽  
Hydrolysis Of

An 8-thionocephalosporin was shown to be a substrate of the beta-lactamase II of Bacillus cereus, a zinc metalloenzyme. Although it is a poorer substrate, as judged by the Kcat./Km parameter, than the corresponding 8-oxocephalosporin, the discrimination against sulphur decreased when the bivalent metal ion in the enzyme active site was varied in the order Mn2+ (the manganese enzyme catalysed the hydrolysis of the oxo compound but not that of the thiono compound), Zn2+, Co2+ and Cd2+. This result is taken as evidence for kinetically significant direct contact between the active-site metal ion of beta-lactamase II and the beta-lactam carbonyl heteroatom. No evidence was obtained, however, for accumulation of an intermediate with such co-ordination present.

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