References of "Van Beeumen, Jos"
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See detailGlycosyl transferase activity of the Escherichia coli penicillin-binding protein 1b: Specificity profile for the substrate
Fraipont, Claudine ULg; Sapunaric, Frédéric ULg; Zervosen, Astrid ULg et al

in Biochemistry (2006), 45(12), 4007-4013

The glycosyl transferase of the Escherichia coli bifunctional penicillin-binding protein (PBP) 1b catalyzes the assembly of lipid-transported N-acetylglucosaminyl-beta-1,4-N-acetylmuramoyl-L-Ala-gamma-D ... [more ▼]

The glycosyl transferase of the Escherichia coli bifunctional penicillin-binding protein (PBP) 1b catalyzes the assembly of lipid-transported N-acetylglucosaminyl-beta-1,4-N-acetylmuramoyl-L-Ala-gamma-D-Glu-meso-A(2)pm-D-Ala-D-Ala units (lipid II) into linear peptidoglycan chains. These units are linked, at C1 of N-acetylmuramic acid (MurNAc), to a C-55 undecaprenyl pyrophosphate. In an in vitro assay, lipid II functions both as a glycosyl donor and as a glycosyl acceptor substrate. Using substrate analogues, it is suggested that the specificity of the enzyme for the glycosyl donor substrate differs from that for the acceptor. The donor substrate requires the presence of both N-acetylglucosamine (GlcNAc) and MurNAc and a reactive group on C1 of the MurNAc and does not absolutely require the lipid chain which can be replaced by uridine. The enzyme appears to prefer an acceptor substrate containing a polyprenyl pyrophosphate on C1 of the MurNAc sugar. The problem of glycan chain elongation that presumably proceeds by the repetitive addition of disaccharide peptide units at their reducing end is discussed. [less ▲]

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See detailMonitoring the zinc affinity of the metallo-beta-lactamase CphA by automated nanoESI-MS
De Vriendt, K.; Van Driessche, G.; Devreese, B. et al

in Journal of the American Society for Mass Spectrometry (2006), 17(2), 180-188

Metallo-beta-lactamases are zinc containing enzymes that are able to hydrolyze and inactivate beta-lactam antibiotics. The subclass B2 enzyme CphA of Aeromonas hydrophila is a unique metallo-p-lactamase ... [more ▼]

Metallo-beta-lactamases are zinc containing enzymes that are able to hydrolyze and inactivate beta-lactam antibiotics. The subclass B2 enzyme CphA of Aeromonas hydrophila is a unique metallo-p-lactamase because it degrades only carbapenems efficiently and is only active when it has one zinc ion bound. A zinc titration experiment was used to study the zinc affinity of the wild-type and of several mutant CphA enzymes. It shows that a second Zn2+ is also bound at high ion concentrations. All samples were analyzed using mass spectrometry in combination with an automated nanoESI source. The metal-free enzyme has a bimodal charge distribution indicative of two conformational states. A completely folded enzyme is detected when the apo-enzyme has bound the first zinc. Intensity ratios of the different enzyme forms were used to deduce the zinc affinities. CphA enzymes mutated in metal ligands show decreased zinc affinity compared to wild-type, especially D120 mutants. [less ▲]

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See detailDramatic broadening of the substrate profile of the Aeromonas hydrophila CphA metallo-beta-lactamase by site-directed mutagenesis
Bebrone, Carine ULg; Anne, C.; De Vriendt, K. et al

in Journal of Biological Chemistry (2005), 280(31), 28195-28202

Among class B beta-lactamases, the subclass B2 CphA enzyme is characterized by a unique specificity profile. CphA efficiently hydrolyzes only carbapenems. In this work, we generated site-directed mutants ... [more ▼]

Among class B beta-lactamases, the subclass B2 CphA enzyme is characterized by a unique specificity profile. CphA efficiently hydrolyzes only carbapenems. In this work, we generated site-directed mutants that possess a strongly broadened activity spectrum when compared with the WT CphA. Strikingly, the N116H/N220G double mutant exhibits a substrate profile close to that observed for the broad spectrum subclass B1 enzymes. The double mutant is significantly activated by the binding of a second zinc ion under conditions where the WT enzyme is non-competitively inhibited by the same ion. [less ▲]

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See detailIDENTIFICATION OF PLACENTAL HUMAN GROWTH-HORMONE AS THE GROWTH HORMONE-V GENE-EXPRESSION PRODUCT
Frankenne, Francis ULg; Scippo, Marie-Louise ULg; Van Beeumen, Jos et al

in Journal Of Clinical Endocrinology And Metabolism (1990), 71(1), 15-18

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See detailThe penicillin-binding site in the exocellular DD-carboxypeptidase-transpeptidase of Actinomadura R39
Duez, Colette ULg; Joris, Bernard ULg; Frère, Jean-Marie ULg et al

in Biochemical Journal (1981), 193

Heat denaturation and Pronase degradation of the complex previously formed between benzylpenicillin and the exocellular DD-carboxypeptidase-transpeptidase of Actinomadura R39 yields a heptapeptide H-Leu ... [more ▼]

Heat denaturation and Pronase degradation of the complex previously formed between benzylpenicillin and the exocellular DD-carboxypeptidase-transpeptidase of Actinomadura R39 yields a heptapeptide H-Leu-Pro-Ala-Ser-Asn-Gly-Val-OH, where the benzylpenicilloyl group is ester-linked to the serine residue. This linkage is very labile and its hydrolysis causes the release of benzylpenicilloate. In contrast, the native benzylpenicilloyl-enzyme complex is very stable (half-life 70h at 370C) and its breakdown proceeds via fragmentation of the bound benzylpenicilloyl group [Fuad, Frere, Ghuysen, Duez & Iwatsubo (1976) Biochem. J. 155, 623-6291. [less ▲]

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