References of "Frère, Jean-Marie"
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See detailThe Bimodular G57-V577 Polypeptide Chain of the Class B Penicillin-Binding Protein 3 of Escherichia Coli Catalyzes Peptide Bond Formation from Thiolesters and Does Not Catalyze Glycan Chain Polymerization from the Lipid II Intermediate
Adam, Maggy; Fraipont, Claudine ULiege; Rhazi, Noureddine ULiege et al

in Journal of Bacteriology (1997), 179(19), 6005-6009

Because the specificity profile of the membrane anchor-free G57-V577 penicillin-binding protein 3 (PBP3) of Escherichia coli for a large series of beta-lactam antibiotics is similar to that of the full ... [more ▼]

Because the specificity profile of the membrane anchor-free G57-V577 penicillin-binding protein 3 (PBP3) of Escherichia coli for a large series of beta-lactam antibiotics is similar to that of the full-size membrane-bound PBP, the truncated PBP is expected to adopt the native folded conformation. The truncated PBP3 functions as a thiolesterase. In aqueous media and in the presence of millimolar concentrations of a properly structured amino compound, it catalyzes the aminolysis of the thiolester until completion, suggesting that the penicillin-binding module of PBP3 is designed to catalyze transpeptidation reactions. In contrast, the truncated PBP3 is devoid of glycan polymerization activity on the E. coli lipid II intermediate, suggesting that the non-penicillin-binding module of PBP3 is not a transglycosylase. [less ▲]

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See detailZn(Ii) Dependence of the Aeromonas Hydrophila Ae036 Metallo-Beta-Lactamase Activity and Stability
Hernandez Valladares, M.; Felici, A.; Weber, Georges ULiege et al

in Biochemistry (1997), 36(38), 11534-41

Two Zn2+ binding sites were found in the Aeromonas hydrophila AE036 metallo-beta-lactamase. The affinity of the first binding site for Zn2+ ions is so high that the dissociation constant could not be ... [more ▼]

Two Zn2+ binding sites were found in the Aeromonas hydrophila AE036 metallo-beta-lactamase. The affinity of the first binding site for Zn2+ ions is so high that the dissociation constant could not be determined, but it is significantly lower than 20 nM. The mono-Zn2+ form of the enzyme exhibits a maximum activity against its carbapenem substrates. The presence of a Zn2+ ion in the second lower affinity binding site results in a loss of enzymatic activity with a Ki value of 46 microM at pH 6.5. The kinetic analysis is in agreement with a noncompetitive inhibition mechanism. The Zn content of the A. hydrophila enzyme is also strongly pH-dependent. With an external Zn2+ ion concentration of 0.4 microM, occupancy of the higher affinity site by metal ions is lower than 10% at pH 5 and 10. The affinity for the second binding site seems to increase from pH 6 to 7.5. Fluorescence emission and circular dichroism spectra revealed slight conformational changes upon titration of the apoenzyme by Zn2+ ions, resulting in the successive saturation of the first and second binding sites. Differential scanning calorimetry transitions and intrinsic fluorescence emission spectra in the presence of increasing concentrations of urea demonstrate that the catalytic zinc strongly stabilizes the conformation of the enzyme whereas the di-Zn enzyme is even more resistant to thermal and urea denaturation than the mono-Zn enzyme. The Zn2+ dependency of the activity of this metallo-beta-lactamase thus appears to be very different from that of the homologous Bacteroides fragilis enzyme for which the presence of two Zn2+ ions per molecule of protein appears to result in maximum activity. [less ▲]

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See detailContribution of Beta-Lactamase Production to the Resistance of Mycobacteria to Beta-Lactam Antibiotics
Quinting, B.; Reyrat, J. M.; Monnaie, D. et al

in FEBS Letters (1997), 406(3), 275-8

Mycobacterium fallax (M. fallax) is naturally sensitive to many beta-lactam antibiotics (MIC < 2 microg/ml) and devoid of beta-lactamase activity. In this paper, we show that the production of the beta ... [more ▼]

Mycobacterium fallax (M. fallax) is naturally sensitive to many beta-lactam antibiotics (MIC < 2 microg/ml) and devoid of beta-lactamase activity. In this paper, we show that the production of the beta-lactamase of Mycobacterium fortuitum by M. fallax significantly increased the MIC values for good substrates of the enzyme, whereas the potency of poor substrates or transient inactivators was not modified. The rates of diffusion of beta-lactams through the mycolic acid layer were low, but for all studied compounds the half-equilibration times were such that they would only marginally affect the MIC values in the absence of beta-lactamase production. These results emphasize the importance of enzymatic degradation as a major factor in the resistance of mycobacteria to penicillins. [less ▲]

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See detailPurification and Properties of the Mycobacterium Smegmatis Mc(2)155 Beta-Lactamase
Quinting, B.; Galleni, Moreno ULiege; Timm, J. et al

in FEMS Microbiology Letters (1997), 149(1), 11-5

The beta-lactamase of Mycobacterium smegmatis mc(2)155 has been purified to protein homogeneity. Its N-terminal sequence and catalytic properties are similar to those of the beta-lactamase produced by ... [more ▼]

The beta-lactamase of Mycobacterium smegmatis mc(2)155 has been purified to protein homogeneity. Its N-terminal sequence and catalytic properties are similar to those of the beta-lactamase produced by Mycobacterium fortuitum D316 and establish this new enzyme as a member of molecular class A. [less ▲]

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See detailThe bla gene of the cephamycin cluster of Streptomyces clavuligerus encodes a class A beta-lactamase of low enzymatic activity.
Perez-Llarena, F.; Martin, Juan F.; Galleni, Moreno ULiege et al

in Journal of bacteriology (1997), 179(19), 6035-40

A gene (bla) encoding a beta-lactamase is present in the cephamycin gene cluster of Streptomyces clavuligerus, the strain producing clavulanic acid and a beta-lactamase inhibitory protein. The bla gene is ... [more ▼]

A gene (bla) encoding a beta-lactamase is present in the cephamycin gene cluster of Streptomyces clavuligerus, the strain producing clavulanic acid and a beta-lactamase inhibitory protein. The bla gene is located 5.1 kb downstream from and in the opposite orientation to cefE, encoding the deacetoxycephalosporin C synthase. The bla gene encodes a 332-residue protein (Mr, 35,218), similar to other class A beta-lactamases produced by actinomycetes. Modification (to SDG) of the SDN conserved motif of class A beta-lactamases as well as of amino acids in otherwise conserved regions in the molecule may explain the low penicillinase and cephalosporinase activities of the protein. The beta-lactamase has been purified to homogeneity and found to bind [3H]benzylpenicillin, a result reflecting a rate-limiting deacylation step. Nucleotide sequences homologous to bla were found in all tested cephamycin producers, but several other Streptomyces species which produce a beta-lactamase do not contain genes for beta-lactam antibiotic biosynthesis. [less ▲]

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See detailSensitivity of Aeromonas hydrophila carbapenemase to delta3-cephems: comparative study with other metallo-beta-lactamases.
Felici, A.; Perilli, M.; Franceschini, N. et al

in Antimicrobial agents and chemotherapy (1997), 41(4), 866-8

Ceftriaxone and ceftriaxone S-oxide behaved as inactivators against the metallo-beta-lactamase of Aeromonas hydrophila AE036 and as substrates for the zinc beta-lactamase produced by Bacillus cereus (569 ... [more ▼]

Ceftriaxone and ceftriaxone S-oxide behaved as inactivators against the metallo-beta-lactamase of Aeromonas hydrophila AE036 and as substrates for the zinc beta-lactamase produced by Bacillus cereus (569/H/9) and Stenotrophomonas maltophilia ULA 511. Moreover, RO 09-1428, a catechol-cephalosporin, was not recognized by the A. hydrophila enzyme. Panipenem, cephalosporin C, cephalosporin C-gamma-lactone, and loracarbef were substrates for the three studied beta-lactamases. [less ▲]

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See detailUnexpected Influence of a C-Terminal-Fused His-Tag on the Processing of an Enzyme and on the Kinetic and Folding Parameters
Ledent, Philippe; Duez, Colette ULiege; Vanhove, Marc et al

in FEBS Letters (1997), 413(2), 194-196

The addition of a poly-His C-terminal extension, designed to facilitate the purification of the protein, to the beta-lactamase of a thermophilic Bacillus licheniformis strain modified the site of action ... [more ▼]

The addition of a poly-His C-terminal extension, designed to facilitate the purification of the protein, to the beta-lactamase of a thermophilic Bacillus licheniformis strain modified the site of action of the signal peptidase. This resulted in the secretion of a protein with a different N-terminus, showing that this type of protein engineering might not always be as 'neutral' as generally assumed. (C) 1997 Federation of European Biochemical Societies. [less ▲]

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See detailSite-directed mutagenesis of glutamate 166 in two beta-lactamases. Kinetic and molecular modeling studies.
Guillaume, Gilliane; Vanhove, M; Lamotte-Brasseur, J et al

in Journal of Biological Chemistry (1997), 272(9), 5438-44

The catalytic pathway of class A beta-lactamases involves an acyl-enzyme intermediate where the substrate is ester-linked to the Ser-70 residue. Glu-166 and Lys-73 have been proposed as candidates for the ... [more ▼]

The catalytic pathway of class A beta-lactamases involves an acyl-enzyme intermediate where the substrate is ester-linked to the Ser-70 residue. Glu-166 and Lys-73 have been proposed as candidates for the role of general base in the activation of the serine OH group. The replacement of Glu-166 by an asparagine in the TEM-1 and by a histidine in the Streptomyces albus G beta-lactamases yielded enzymes forming stable acyl-enzymes with beta-lactam antibiotics. Although acylation of the modified proteins by benzylpenicillin remained relatively fast, it was significantly impaired when compared to that observed with the wild-type enzyme. Moreover, the E166N substitution resulted in a spectacular modification of the substrate profile much larger than that described for other mutations of Omega-loop residues. Molecular modeling studies indicate that the displacement of the catalytic water molecule can be related to this observation. These results confirm the crucial roles of Glu-166 and of the "catalytic" water molecule in both the acylation and the deacylation processes. [less ▲]

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See detailThe Penicillin sensory transducer, blar, involved in the inducibility of beta-lactamase synthesis in bacillus licheniformis is embedded in the plasma membrane via a four-alpha-helix bundle
Hardt, Karin; Joris, Bernard ULiege; Lepage, Sophie et al

in Molecular Microbiology (1997), 23(5), 935-944

Prediction studies, conformational analyses and membrane-topology mapping lead to the conclusion that the penicillin sensory transducer, BlaR, involved in the inducibility of beta-lactamase synthesis in ... [more ▼]

Prediction studies, conformational analyses and membrane-topology mapping lead to the conclusion that the penicillin sensory transducer, BlaR, involved in the inducibility of beta-lactamase synthesis in Bacillus licheniformis, is embedded in the plasma membrane bilayer via four transmembrane segments TM1-TM4 that forma four-alpha-helix bundle. The extracellular 262-amino-acid-residue polypeptide, S340-R601, that is fused at the carboxy end of TM4, possesses the amino acid sequence signature of a penicilloyl serine transferase. It probably functions as penicillin sensor. As an independent entity, this polypeptide behaves as a high-affinity penicillin-binding protein. As a component of the full-size BlaR, it adopts a different conformation presumably because of interactions with the extracellular 63-amino-acid-residue P53-S115 loop that connects TM2 and TM3. Reception of the penicillin-induced signal requires a precise conformation of the sensor but it does not involve penicilloylation of the serine residue S402 of motif STYK. Signal transmission through the plasma membrane by the four-alpha-helix bundle may proceed in a way comparable to that of the aspartate receptor, Tar. Signal emission in the cytosol by the intracellular 189-amino-acid-residue Y134-K322 loop that connects TM3 and TM4, may proceed via the activation of a putative metallopeptidase. [less ▲]

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See detailOverproduction and purification of the Aeromonas hydrophila CphA metallo-beta-lactamase expressed in Escherichia coli.
Hernandez Villadares, M.; Galleni, Moreno ULiege; Frère, Jean-Marie ULiege et al

in Microbial drug resistance (Larchmont, N.Y.) (1996), 2(2), 253-6

The Aeromonas hydrophila CphA metallo-beta-lactamase was overexpressed in a soluble secreted form in Escherichia coli using a T7 RNA polymerase-based expression system, and a simple protocol based on a ... [more ▼]

The Aeromonas hydrophila CphA metallo-beta-lactamase was overexpressed in a soluble secreted form in Escherichia coli using a T7 RNA polymerase-based expression system, and a simple protocol based on a single cation-exchange chromatographic step was developed, which is suitable for rapid purification of the overexpressed enzyme from E. coli lysates. A yield of up to 30 micrograms of purified enzyme per milliliter of culture was obtained. The purified enzyme preparation showed properties identical to those previously reported in the literature. [less ▲]

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See detailThree hTIM mutants that provide new insights on why TIM is a dimer
Mainfroid, Véronique; Terpstra, Peter; Beauregard, Marc et al

in Journal of Molecular Biology (1996), 257(2), 441-56

Human triosephosphate isomerase (hTIM), a dimeric enzyme, was altered by site-directed mutagenesis in order to determine whether it can be dissociated into monomers. Two hTIM mutants were produced, in ... [more ▼]

Human triosephosphate isomerase (hTIM), a dimeric enzyme, was altered by site-directed mutagenesis in order to determine whether it can be dissociated into monomers. Two hTIM mutants were produced, in which a glutamine residue was substituted for either Met14 or Arg98, both of which are interface residuces. These substitutions strongly interfere with TIM subunit association, since these mutant TIMs appear to exist as compact monomers in dynamic equilibrium with dimers. In kinetic studies, the M14Q mutant exhibits significant catalytic activity, while the R98Q enzyme is inactive. The M14Q enzyme is nevertheless much less active than unmutated hTIM. Moreover, its specific activity is concentration dependent, suggesting a dissociation process in which the monomers are inactive. In order to determine the conformational stability of the wild-type and mutant hTIMs, unfolding of all three enzymes was monitored by circular dichroism and tryptophan fluorescence spectroscopy. In each case, protein stability is concentration dependent, and the unfolding reaction is compatible with a two-state model involving the native dimer and unfolded monomers. The conformational stability of hTIM, as estimated according to this model, is 19.3 (+/-0.4) kcal/mol. The M14Q and R98Q replacements significantly reduce enzyme stability, since the free energies of unfolding are 13.8 and 13.5 (+/- 0.3) kcal/mol respectively, for the mutants, A third mutant, in which the M14Q and R98Q replacements are cumulated, behaves like a monomer. The stability of this mutant is not concentration-dependent, and the unfolding reaction is assigned to a transition from a folded monomer to an unfolded monomer. The conformational stability of this double mutant is estimated 2.5 (+/-0.1) kcal/mol. All these data combined suggest that TIM monomers are thermodynamically unstable. This might explain why TIM occurs only as a dimer. [less ▲]

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See detailThe catalytic mechanism of beta-lactamases: NMR titration of an active-site lysine residue of the TEM-1 enzyme.
Damblon, Christian ULiege; Raquet, X.; Lian, L. Y. et al

in Proceedings of the National Academy of Sciences of the United States of America (1996), 93(5), 1747-52

Beta-Lactamases are widespread in the bacterial world, where they are responsible for resistance to penicillins, cephalosporins, and related compounds, currently the most widely used antibacterial agents ... [more ▼]

Beta-Lactamases are widespread in the bacterial world, where they are responsible for resistance to penicillins, cephalosporins, and related compounds, currently the most widely used antibacterial agents. Detailed structural and mechanistic understanding of these enzymes can be expected to guide the design of new antibacterial compounds resistant to their action. A number of high-resolution structures are available for class A beta-lactamases, whose catalytic mechanism involves the acylation of a serine residue at the active site. The identity of the general base which participates in the activation of this serine residue during catalysis has been the subject of controversy, both a lysine residue and a glutamic acid residue having been proposed as candidates for this role. We have used the pH dependence of chemical modification of epsilon-amino groups by 2,4,6,-trinitrobenzenesulfonate and the pH dependence of the epsilon-methylene 1H and 13C chemical shifts (in enzyme selectively labeled with [epsilon-13C]lysine) to estimate the pKa of the relevant lysine residue, lysine-73, of TEM-1 beta-lactamase. Both methods show that the pKa of this residue is > 10, making it very unlikely that this residue could act as a proton acceptor in catalysis. An alternative mechanism in which this role is performed by glutamate-166 through an intervening water molecule is described. [less ▲]

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See detailThe Enigmatic Catalytic Mechanism of Active-Site Serine Beta-Lactamases
Galleni, Moreno ULiege; Lamotte-Brasseur, J.; Raquet, X. et al

in Biochemical Pharmacology (1995), 49(9), 1171-8

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See detailSaturation of Penicillin-Binding Protein 1 by Beta-Lactam Antibiotics in Growing Cells of Bacillus Licheniformis
Lepage, Sylvie ULiege; Lakaye, Bernard ULiege; Galleni, Moreno ULiege et al

in Molecular Microbiology (1995), 16(2), 365-72

With the help of a new highly sensitive method allowing the quantification of free penicillin-binding proteins (PBPs) and of an integrated mathematical model, the progressive saturation of PBP1 by various ... [more ▼]

With the help of a new highly sensitive method allowing the quantification of free penicillin-binding proteins (PBPs) and of an integrated mathematical model, the progressive saturation of PBP1 by various beta-lactam antibiotics in growing cells of Bacillus licheniformis was studied. Although the results confirmed PBP1 as a major lethal target for these compounds, they also underlined several weaknesses in our present understanding of this phenomenon. In growing cells, but not in resting cells, the penicillin target(s) appeared to be somewhat protected from the action of the inactivators. In vitro experiments indicated that amino acids, peptides and depsipeptides mimicking the peptide moiety of the nascent peptidoglycan significantly interfered with the acylation of PBP1 by the antibiotics. In addition, the level of PBP1 saturation at antibiotic concentrations corresponding to the minimum inhibitory concentrations was not constant, suggesting that additional, presently undiscovered, factors might be necessary to account for the experimental observations. [less ▲]

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See detailDd-Peptidases and Beta-Lactamases: Catalytic Mechanisms and Specificities
Galleni, Moreno ULiege; Raquet, X.; Lamotte-Brasseur, J. et al

in Journal of Chemotherapy (Florence, Italy) (1995), 7(1), 3-7

DD-peptidases and beta-lactamases share several common properties, including the formation of an acylenzyme intermediate in their catalytic pathways. In their interactions with beta-lactam antibiotics ... [more ▼]

DD-peptidases and beta-lactamases share several common properties, including the formation of an acylenzyme intermediate in their catalytic pathways. In their interactions with beta-lactam antibiotics, the stability of this intermediate is much higher with the peptidases than with the beta-lactamases. The structural factors responsible for this difference have not been identified. The evolution of beta-lactamases is taking place before our eyes, since mutants are constantly selected which can hydrolyze the molecules newly introduced as "beta-lactamase resistant" in the chemotherapeutic arsenal. [less ▲]

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See detailAmpd, Essential for Both Beta-Lactamase Regulation and Cell Wall Recycling, Is a Novel Cytosolic N-Acetylmuramyl-L-Alanine Amidase
Jacobs, Christine ULiege; Joris, Bernard ULiege; Jamin, M. et al

in Molecular Microbiology (1995), 15(3), 553-9

In enterobacteria, the ampD gene encodes a cytosolic protein which acts as a negative regulator of beta-lactamase expression. It is shown here that the AmpD protein is a novel N-acetylmuramyl-L-alanine ... [more ▼]

In enterobacteria, the ampD gene encodes a cytosolic protein which acts as a negative regulator of beta-lactamase expression. It is shown here that the AmpD protein is a novel N-acetylmuramyl-L-alanine amidase (E.C.3.5.1.28) participating in the intracellular recycling of peptidoglycan fragments. Surprisingly, AmpD exhibits an exclusive specificity for substrates containing anhydro muramic acid. This anhydro bond is mainly found in the peptidoglycan degradation products formed by the periplasmic lytic transglycosylases and thus might behave as a 'recycling tag' allowing the enzyme to distinguish these fragments from the newly synthesized peptidoglycan precursors. The AmpD substrate (or substrates) which accumulates in the absence of the corresponding enzymatic activity acts as an intracellular positive effector for beta-lactamase expression and might represent an element of a communication network between the chromosome and the cell wall peptidoglycan. [less ▲]

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See detailContribution of Mutant Analysis to the Understanding of Enzyme Catalysis: The Case of Class a Beta-Lactamases
Matagne, André ULiege; Frère, Jean-Marie ULiege

in Biochimica et Biophysica Acta (1995), 1246(2), 109-27

Class A beta-lactamases represent a family of well studied enzymes. They are responsible for many antibiotic resistance phenomena and thus for numerous failures in clinical chemotherapy. Despite the facts ... [more ▼]

Class A beta-lactamases represent a family of well studied enzymes. They are responsible for many antibiotic resistance phenomena and thus for numerous failures in clinical chemotherapy. Despite the facts that five structures are known at high resolution and that detailed analyses of enzymes modified by site-directed mutagenesis have been performed, their exact catalytic mechanism remains controversial. This review attempts to summarize and to discuss the many available data. [less ▲]

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See detailKinetic Study of Interaction between Brl 42715, Beta-Lactamases, and D-Alanyl-D-Alanine Peptidases
Matagne, André ULiege; Ledent, Philippe; Monnaie, Didier et al

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 ▲]

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See detailStreptomyces K15 active-site serine DD-transpeptidase: specificity profile for peptide, thiol ester and ester carbonyl donors and pathways of the transfer reactions.
Grandchamps, Jacqueline; Nguyen-Distèche, Martine ULiege; Damblon, Christian ULiege et al

in Biochemical Journal (1995), 307(Pt 2), 335-339

The Streptomyces K15 transferase is a penicillin-binding protein presumed to be involved in bacterial wall peptidoglycan crosslinking. It catalyses cleavage of the peptide, thiol ester or ester bond of ... [more ▼]

The Streptomyces K15 transferase is a penicillin-binding protein presumed to be involved in bacterial wall peptidoglycan crosslinking. It catalyses cleavage of the peptide, thiol ester or ester bond of carbonyl donors Z-R1-CONH-CHR2-COX-CHR3-COO- (where X is NH, S or O) and transfers the electrophilic group Z-R1-CONH-CHR2-CO to amino acceptors via an acyl-enzyme intermediate. Kinetic data suggest that the amino acceptor behaves as a simple alternative nucleophile at the level of the acyl-enzyme in the case of thiol ester and ester donors, and that it binds to the enzyme.carbonyl donor Michaelis complex and influences the rate of enzyme acylation by the carbonyl donor in the case of amide donors. Depending on the nature of the scissile bond, the enzyme has different requirements for substituents at positions R1, R2 and R3. [less ▲]

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See detailThe 3-D structure of a zinc metallo-beta-lactamase from Bacillus cereus reveals a new type of protein fold
Carfi, A.; Pares, S.; Duée, E. et al

in EMBO Journal (1995), 14(20), 4914-4921

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