References of "Ghuysen, Jean-Marie"
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See detailEloge academique du professeur Maurice Welsch, membre titulaire et ancien président
Ghuysen, Jean-Marie ULg; Reginster, M.

Article for general public (1987)

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See detailThe crystal structure of the β-lactamase of Streptomyces albus G at 0.3 nm resolution
Dideberg, Otto; Charlier, Paulette ULg; Wery, Jean-Paul et al

in Biochemical Journal (1987), 245(3), 911-913

The crystal structure of the beta-lactamase of Streptomyces albus G has been solved at 0.3 nm resolution by X-ray-diffraction methods. The enzyme is a typical two-domain protein. One domain consists of ... [more ▼]

The crystal structure of the beta-lactamase of Streptomyces albus G has been solved at 0.3 nm resolution by X-ray-diffraction methods. The enzyme is a typical two-domain protein. One domain consists of five alpha-helices, and the other is five-stranded beta-sheet with alpha-helices on both sides of the sheet. The active-site serine residue (Ser-48) is within a cleft located between the two domains. [less ▲]

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See detailThe active sites of the β-lactamases of Streptomyces cacaoi and Streptomyces albus G
Demeester, Fabien; Joris, Bernard ULg; Lenzini, Mauro V. et al

in Biochemical Journal (1987), 244(2), 427-432

The active-site serine of the extracellular beta-lactamases of Streptomyces cacaoi and Streptomyces albus G has been labelled with beta-iodopenicillanate. The determination of the sequence of the labelled ... [more ▼]

The active-site serine of the extracellular beta-lactamases of Streptomyces cacaoi and Streptomyces albus G has been labelled with beta-iodopenicillanate. The determination of the sequence of the labelled peptides obtained after trypsin digestion of the denatured proteins indicate both enzymes to be class A beta-lactamases. Surprisingly the two Streptomyces enzymes do not appear to be especially homologous, and none of them exhibited a high degree of homology with the Streptomyces R61 DD-peptidase. Our data confirm that, as a family of homologous enzymes, class A is rather heterogeneous, with only a small number of conserved residues in all members of the class. [less ▲]

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See detailPrimary structure of the Streptomyces R61 extracellular DD-peptidase. 1. Cloning into Streptomyces lividans and nucleotide sequence of the gene
Duez, Colette ULg; Fraipont, Claudine ULg; Joris, Bernard ULg et al

in European Journal of Biochemistry (1987), 162

An 11450-base DNA fragment containing the gene for the extracellular active-site serine DD-peptidase of Streptomyces R61 was cloned in Streptomyces lividans using the high-copy-number plasmid pIJ702 as ... [more ▼]

An 11450-base DNA fragment containing the gene for the extracellular active-site serine DD-peptidase of Streptomyces R61 was cloned in Streptomyces lividans using the high-copy-number plasmid pIJ702 as vector. Amplified expression of the excreted enzyme was observed. Producing clones were identified with the help of a specific antiserum directed against the pure DD-peptidase. The coding sequence of the gene was then located by hybridization with a specific nucleotide probe and sub-fragments were obtained from which the nucleotide sequence of the structural gene and the putative promoter and terminator regions were determined. The sequence suggests that the gene codes for a 406-amino-acid protein precursor. When compared with the excreted, mature DD-peptidase, this precursor possesses a cleavable 31-amino-acid N-terminal extension which has the characteristics of a signal peptide, and a cleavable 26-amino-acid C-terminal extension. On the basis of the data of Joris et al. (following paper in this journal), the open reading frame coding for the synthesis of the DD-peptidase was established. Comparison of the primary structure of the Streptomyces R61 DD-peptidase with those of several active-site serine β-lactamases and penicillin-binding proteins of Escherichia coli shows homology in those sequences that comprise the active-site serine residue. When the comparison is broadened to the complete amino acid sequences, significant homology is observed only for the pair Streptomyces R61 DD-peptidase/Escherichia coli ampC β-lactamase (class C). Since the Streptomyces R61 DD-peptidase and β-lactamases of class A have very similar three-dimensional structures [Kelly et al. (1986) Science (Wash. DC) 231, 1429–1431; Samraoui et al. (1986) Nature (Lond.) 320, 378–380], it is concluded that these tertiary features are probably also shared by the β-lactamases of class C, i.e. that the Streptomyces R61 DD-peptidase and the β-lactamases of classes A and C are related in an evolutionary sense. [less ▲]

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See detailStreptomyces K15 DD-peptidase-catalysed reactions with suicide β-lactam carbonyl donors
Leyh-Bouille, Mélina; Nguyen-Distèche, Martine ULg; Pirlot, Suzanne et al

in Biochemical Journal (1986), 235(1), 177-182

The values of the kinetic parameters that govern the interactions between the Streptomyces K15 DD-peptidase and beta-lactam compounds were determined by measuring the inactivating effect that these ... [more ▼]

The values of the kinetic parameters that govern the interactions between the Streptomyces K15 DD-peptidase and beta-lactam compounds were determined by measuring the inactivating effect that these compounds exert on the transpeptidase activity of the enzyme and, in the case of [14C]benzylpenicillin and [14C]cefoxitin, by measuring the amounts of acyl-enzyme formed during the reaction. K15 DD-peptidase binds benzylpenicillin or cefoxitin at a molar ratio of 1:1. Benzylpenicilloate is the major product released during breakdown of the acyl-enzyme formed with benzylpenicillin. Benzylpenicillin is not a better acylating agent than the amide Ac2-L-Lys-D-Ala-D-Ala and ester Ac2-L-Lys-D-Ala-D-lactatecarbonyl-donor substrates. beta-Lactam compounds possessing a methoxy group on the alpha-face of the molecule show high inactivating potency. [less ▲]

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See detailActive-site-serine D-alanyl-D-alanine-cleaving-peptidase-catalysed acyl-transfer reactions. Procedures for studying the penicillin-binding proteins of bacterial plasma membranes
Ghuysen, Jean-Marie ULg; Frère, Jean-Marie ULg; Leyh-Bouille, Mélina et al

in Biochemical Journal (1986), 235(1), 159-165

Under certain conditions, the values of the parameters that govern the interactions between the active-site-serine D-alanyl-D-alanine-cleaving peptidases and both carbonyl-donor substrates and beta-lactam ... [more ▼]

Under certain conditions, the values of the parameters that govern the interactions between the active-site-serine D-alanyl-D-alanine-cleaving peptidases and both carbonyl-donor substrates and beta-lactam suicide substrates can be determined on the basis of the amounts of (serine ester-linked) acyl-protein formed during the reactions. Expressing the 'affinity' of a beta-lactam compound for a DD-peptidase in terms of second-order rate constant of enzyme acylation and first-order rate constant of acyl-enzyme breakdown rests upon specific features of the interaction (at a given temperature) and permits study of structure-activity relationships, analysis of the mechanism of intrinsic resistance and use of a 'specificity index' to define the capacity of a beta-lactam compound of discriminating between various sensitive enzymes. From knowledge of the first-order rate constant of acyl-enzyme breakdown and the given time of incubation, the beta-lactam compound concentrations that are necessary to achieve given extents of DD-peptidase inactivation can be converted into the second-order rate constant of enzyme acylation. The principles thus developed can be applied to the study of the multiple penicillin-binding proteins that occur in the plasma membranes of bacteria. [less ▲]

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See detailStreptomyces K15 DD-peptidase-catalysed reactions with ester and amide carbonyl donors
Nguyen-Distèche, Martine ULg; Leyh-Bouille, Mélina; Pirlot, Suzanne et al

in Biochemical Journal (1986), 235(1), 167-176

In water, the purified 26 000-Mr membrane-bound DD-peptidase of Streptomyces K15 hydrolyses the ester carbonyl donor Ac2-L-Lys-D-Ala-D-lactate (release of D-lactate) and the amide carbonyl donor Ac2-L-Lys ... [more ▼]

In water, the purified 26 000-Mr membrane-bound DD-peptidase of Streptomyces K15 hydrolyses the ester carbonyl donor Ac2-L-Lys-D-Ala-D-lactate (release of D-lactate) and the amide carbonyl donor Ac2-L-Lys-D-Ala-D-Ala (release of D-alanine) with accumulation of acyl- (Ac2-L-Lys-D-alanyl-)enzyme. Whereas hydrolysis of the ester substrate proceeds to completion, hydrolysis of the amide substrate is negligible because of the capacity of the K15 DD-peptidase for utilizing the released D-alanine in a transfer reaction (Ac2-L-Lys-D-Ala-D-Ala + D-Ala----Ac2-L-Lys-D-Ala-D-Ala + D-Ala) that maintains the concentration of the amide substrate at a constant level. In the presence of an amino acceptor X-NH2 (Gly-Gly or Gly-L-Ala) related to the Streptomyces peptidoglycan, both amide and ester carbonyl donors are processed without detectable accumulation of acyl-enzyme. Under proper conditions, the acceptor activity of water and, in the case of the amide substrate, the acceptor activity of the released D-alanine can be totally overcome so that the two substrates are quantitatively converted into transpeptidated product Ac2-L-Lys-D-Ala-NH-X (and hydrolysis is prevented). Experimental evidence suggests that the amino acceptor modifies both the binding of the carbonyl donor to the enzyme and the ensuing rate of enzyme acylation. [less ▲]

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See detailOn the origin of bacterial resistance to penicillin: comparison of a beta-lactamase and a penicillin target
Kelly, Judith A.; Dideberg, Otto; Charlier, Paulette ULg et al

in Science (1986), 231

Structural data are now available for comparing a penicillin target enzyme, the D-alanyl-D-alanine-peptidase from Streptomyces R61, with a penicillin-hydrolyzing enzyme, the beta-lactamase from Bacillus ... [more ▼]

Structural data are now available for comparing a penicillin target enzyme, the D-alanyl-D-alanine-peptidase from Streptomyces R61, with a penicillin-hydrolyzing enzyme, the beta-lactamase from Bacillus licheniformis 749/C. Although the two enzymes have distinct catalytic properties and lack relatedness in their overall amino acid sequences except near the active-site serine, the significant similarity found by x-ray crystallography in the spatial arrangement of the elements of secondary structure provides strong support for earlier hypotheses that beta-lactamases arose from penicillin-sensitive D-alanyl-D-alanine-peptidases involved in bacterial wall peptidoglycan metabolism. [less ▲]

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See detailCloning and amplified expression in Streptomyces lividans of a gene encoding extracellular β-lactamase from Streptomyces albus G
Dehottay, Philippe; Dusart, Jean; Duez, Colette ULg et al

in Gene (1986), 42(1), 31-36

A 4.9-kb DNA fragment containing the bla gene for the extracellular beta-lactamase (BLA) of Streptomyces albus G was cloned in Streptomyces lividans using the conjugative, low-copy-number plasmid pIJ61 as ... [more ▼]

A 4.9-kb DNA fragment containing the bla gene for the extracellular beta-lactamase (BLA) of Streptomyces albus G was cloned in Streptomyces lividans using the conjugative, low-copy-number plasmid pIJ61 as vector. No expression of bla was observed when this DNA fragment was introduced into Escherichia coli HB101 on a plasmid vector. A 1.5-kb PstI-SstI fragment containing the bla gene was cloned in S. lividans on the nonconjugative, high-copy-number plasmid pIJ702. A tenfold higher yield of BLA was obtained from S. lividans carrying this plasmid than from S. albus G grown under optimal production conditions. The BLA from the clone reacts with beta-iodopenicillanate according to a branched pathway which is characteristic of the original S. albus G BLA enzyme. [less ▲]

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See detailβ-Lactam-induced Proteus L-forms
Ghuysen, Jean-Marie ULg; Nguyen-Distèche, Martine ULg; Rousset, André

in Madoff, Sarabelle (Ed.) The Bacterial L-Forms, vol. 17 (1986)

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See detail2.8-Å Structure of penicillin-sensitive D-alanyl carboxypeptidase-transpeptidase from Streptomyces R61 and complexes with β-lactams
Kelly, Judith A; Knox, James R; Moews, Paul C et al

in Journal of Biological Chemistry (1985), 260(10), 6449-6458

The crystallographic structure of the penicillin-sensitive D-alanyl carboxypeptidase-transpeptidase from Streptomyces R61 has been solved to 2.8-A resolution. The 38,000-dalton serine peptidase has two ... [more ▼]

The crystallographic structure of the penicillin-sensitive D-alanyl carboxypeptidase-transpeptidase from Streptomyces R61 has been solved to 2.8-A resolution. The 38,000-dalton serine peptidase has two regions of secondary structure, an alpha/beta cluster, and a region which contains five helical segments. The beta sheet is composed of five beta strands. The tertiary structure has no homology with the classic serine proteases or with the zinc carboxypeptidases. The binding at a common site of three types of beta-lactam (a penicillin, a cephalosporin, a monocyclic beta-lactam) and a desazacyclobutanone has been observed in Fourier difference maps. The binding site sequence is Val-Gly-Ser-Val-Thr-Lys. The beta-lactam ring lies near the enzyme's catalytic serine at position 37, and the C3 substituent of a cephalosporin falls near lysine 40. [less ▲]

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See detailDes-, syn- and anti-oxyimino-Δ3-cephalosporins. Intrinsic reactivity and reaction with RTEM-2 serine β-lactamase and D-alanyl-D-alanine-cleaving serine and zinc-containing peptidases
Laurent, Guy; Durant, François; Frère, Jean-Marie ULg et al

in Biochemical Journal (1984), 218(3), 933-937

The presence and configuration (syn or anti) of an oxyimino group in the 7 (beta)-acyl side chain of 3-cephems do not modify the intrinsic reactivity of the beta-lactam ring, but have highly enzyme ... [more ▼]

The presence and configuration (syn or anti) of an oxyimino group in the 7 (beta)-acyl side chain of 3-cephems do not modify the intrinsic reactivity of the beta-lactam ring, but have highly enzyme-specific effects. When compared with the corresponding desoxyimino beta-lactam compound: (i) with the plasmid-mediated Escherichia coli RTEM-2 serine beta-lactamase, the substrate activity of the anti isomer is increased and that of the syn isomer is decreased; (ii) with the Streptomyces R61 serine D-alanyl-D-alanine cleaving peptidase (a highly penicillin-sensitive enzyme), the rate of enzyme acylation is not or only little affected when the oxyimino group is in the syn configuration, but is decreased when the oxyimino group is in the anti configuration; (iii) with the Actinomadura R39 serine D-alanyl-D-alanine-cleaving peptidase (an exceedingly highly penicillin-sensitive enzyme), the rate of enzyme acylation is unaffected whatever the configuration of the substituent. The oxidation of the sulphur atom of the dihydrothiazine ring on the beta-face of the molecule makes it both a poorer inactivator of the DD-peptidases and a poorer substrate of the beta-lactamase. The Streptomyces albus G Zn2+-containing D-alanyl-D-alanine-cleaving peptidase (a highly penicillin-resistant enzyme) remains highly resistant to all compounds tested. [less ▲]

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See detailTheoretical study of the C-N bond breakage catalyzed by the serine peptidases
Dive, Georges ULg; Peeters, Daniel; Leroy, Georges et al

in Journal of Molecular Structure : Theochem (1984), 16

The conditions of C---N bond breakage by the serine peptidases have been analysed. A two-way table has been generated where either formamide or protonated formamide serves as minimal model of the scissile ... [more ▼]

The conditions of C---N bond breakage by the serine peptidases have been analysed. A two-way table has been generated where either formamide or protonated formamide serves as minimal model of the scissile C---N bond and where either methanol or the couple CH3O− H+ serves as minimal model of the attacking nucleophile. An addition-elimination reaction is proposed which links the enzyme acylation and deacylation steps. [less ▲]

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See detailActive-site-directed inactivators of the Zn2+-containing D-alanyl-D-alanine-cleaving carboxypeptidase of Streptomyces albus G.
Charlier, Paulette ULg; Dideberg, Otto; Jamoulle, Jean-Claude et al

in Biochemical Journal (1984), 219(3), 763-772

Several types of active-site-directed inactivators (inhibitors) of the Zn2+-containing D-alanyl-D-alanine-cleaving carboxypeptidase were tested. (i) Among the heavy-atom-containing compounds examined ... [more ▼]

Several types of active-site-directed inactivators (inhibitors) of the Zn2+-containing D-alanyl-D-alanine-cleaving carboxypeptidase were tested. (i) Among the heavy-atom-containing compounds examined, K2Pt(C2O4)2 inactivates the enzyme with a second-order rate constant of about 6 X 10(-2)M-1 X S-1 and has only one binding site located close to the Zn2+ cofactor within the enzyme active site. (ii) Several compounds possessing both a C-terminal carboxylate function and, at the other end of the molecule, a thiol, hydroxamate or carboxylate function were also examined. 3-Mercaptopropionate (racemic) and 3-mercaptoisobutyrate (L-isomer) inhibit the enzyme competitively with a Ki value of 5 X 10 X 10(-9)M. (iii) Classical beta-lactam compounds have a very weak inhibitory potency. Depending on the structure of the compounds, enzyme inhibition may be competitive (and binding occurs to the active site) or non-competitive (and binding causes disruption of the protein crystal lattice). (iv) 6-beta-Iodopenicillanate inactivates the enzyme in a complex way. At high beta-lactam concentrations, the pseudo-first-order rate constant of enzyme inactivation has a limit value of 7 X 10(-4)S-1 X 6-beta-Iodopenicillanate binds to the active site just in front of the Zn2+ cofactor and superimposes histidine-190, suggesting that permanent enzyme inactivation is by reaction with this latter residue. [less ▲]

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See detailOn the structural analogy between D-alanyl-D-alanine terminated peptides and β-lactam antibiotics
Brasseur, Josette ULg; Dive, Georges ULg; Ghuysen, Jean-Marie ULg

in European Journal of Medicinal Chemistry (1984), 4

Structural analogy between D-alanyl-D-alanine terminated peptides (and analogues) of varying substrate activity toward D-alanyl-D-alanine-cleaving peptidases, and bicyclic fused ring azetidinone ... [more ▼]

Structural analogy between D-alanyl-D-alanine terminated peptides (and analogues) of varying substrate activity toward D-alanyl-D-alanine-cleaving peptidases, and bicyclic fused ring azetidinone structures of varying inactivating potency toward the same enzymes has been exa-mihed by comparing the relative spatial disposition of the carboxylate function at the C-terminal position and the amide function at the N-terminal position with respect to the scissile amide bond at the central position. The observed variations in the geometric parameters and the molecular electrostatic potential maps generated by these functional groups suggest multiple modes of binding. In the monobactam sulfazecin, the relative disposition of at least the scissile amide bond and the terminal sulphamate group is comparable to that of the corresponding functions in the bicyclic β-lactams. [less ▲]

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See detailInteraction between monobactams and model D-alanyl-D-alanine-cleaving peptidases
Frère, Jean-Marie ULg; Klein, Daniel; Kelly, Judith A et al

in FEMS Microbiology Letters (1984), 21

Several monobactams reacted with the serine dd-peptidases of Streptomyces R61 and Actinomadura R39 in a manner similar to that of bicyclic penicillins and cephalosporins. The dissociation constants of the ... [more ▼]

Several monobactams reacted with the serine dd-peptidases of Streptomyces R61 and Actinomadura R39 in a manner similar to that of bicyclic penicillins and cephalosporins. The dissociation constants of the Michaelis complexes formed between the R61 enzyme and sulfazecin (32 μM) and between the R39 peptidase and SQ 26324 (0.35 μM) had the lowest values ever observed with any β-lactam compound, suggesting an excellent fit of these two monobactams with the active sites of the respective enzymes. Azthreonam had a very poor inactivating potency, confirming its high selective reactivity towards the penicillin binding protein No. 3 of Escherichia coli. The Zn2+dd-peptidase (from Streptomyces albus G) had a high intrinsic resistance to β-lactam compounds whether they possessed a mono- or a bicyclic structure. [less ▲]

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See detailStudy of the Zn-containing DD-carboxypeptidase of Streptomyces albus G by small-angle X-ray scattering in solution.
Labischinski, Harald; Giesbrecht, Peter; Fischer, E. et al

in European Journal of Biochemistry (1984), 138(1), 83-87

Study of the Zn2+-containing D-alanyl-D-alanine-cleaving carboxypeptidase of Streptomyces albus G by small-angle X-ray scattering in solution yielded the following molecular parameters: radius of gyration ... [more ▼]

Study of the Zn2+-containing D-alanyl-D-alanine-cleaving carboxypeptidase of Streptomyces albus G by small-angle X-ray scattering in solution yielded the following molecular parameters: radius of gyration R = 1.82 +/- 0.05 nm; largest diameter D = 5.9 +/- 0.2 nm; relative molecular mass Mr = 17000 +/- 2000; volume V approximately equal to 35 +/- 2 nm3; degree of hydration: 0.25 +/- 0.02 g water/g protein. By reference to theoretical scattering curves of rigid triaxial homogeneous bodies, a model which fits all experimental data is an elliptical cylinder. Such a model is compatible with that observed in the crystal structure. At those high concentrations necessary to form inactive enzyme-ligand associations the non-competitive beta-lactam inhibitors, cephalothin and cephalosporin C, drastically altered the scattering behaviour of the protein. [less ▲]

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See detailBacterial wall peptidoglycan, DD-peptidases and beta-lactam antibiotics
Ghuysen, Jean-Marie ULg; Frère, Jean-Marie ULg; Leyh-Bouille, Mélina et al

in Scandinavian Journal of Infectious Diseases (1984), 42

Wall peptidoglycan expansion in bacteria rests upon a cytoplasmic D-Ala: D-Ala ligase (ADP) which catalyses synthesis of a D-Ala-D-Ala dipeptide (with accompanying hydrolysis of one molecule of ATP) and a ... [more ▼]

Wall peptidoglycan expansion in bacteria rests upon a cytoplasmic D-Ala: D-Ala ligase (ADP) which catalyses synthesis of a D-Ala-D-Ala dipeptide (with accompanying hydrolysis of one molecule of ATP) and a set of DD-peptidases which utilize this D-Ala-D-Ala dipeptide--once it has been translocated at the outer face of the plasma membrane as the C-terminal portion of a disaccharide peptide unit--as carbonyl donor for transpeptidation and carboxypeptidation reactions (without additional energy expenditure). Four DD-peptidases have been selected which differ from each other with respect to the effects that amino compounds exert on the fate and rate of consumption of a D-Ala-D-Ala terminated amide carbonyl donor analogue. They serve as models to understand the different mechanisms by which the DD-peptidases perform catalysis and show widely varying responses to the action of beta-lactams, from extreme sensitivity to very high resistance. [less ▲]

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See detailExploration of active sites of DD-peptidases
Ghuysen, Jean-Marie ULg

in Paton, William; Mitchel, James; Turner, Paul (Eds.) Iuphar 9th International Congress of Pharmacology, London 1984. Proceedings (1984)

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See detailThe complete amino acid sequence of the Zn2+-containing D-alanyl-D-alanine-cleaving carboxypeptidase of streptomyces albus G
Joris, Bernard ULg; Van Beeumen, Jozef; Casagrande, Fabiana et al

in European Journal of Biochemistry (1983), 130(1), 53-69

The 22076-Mr Zn2+-containing D-alanyl-D-alanine-cleaving carboxypeptidase of Streptomyces abuls G effectively catalyses the transfer of the N alpha, N epsilon-diacetyl-L-lysyl-D-alanyl electrophilic group ... [more ▼]

The 22076-Mr Zn2+-containing D-alanyl-D-alanine-cleaving carboxypeptidase of Streptomyces abuls G effectively catalyses the transfer of the N alpha, N epsilon-diacetyl-L-lysyl-D-alanyl electrophilic group of the standard tripeptide substrate N alpha, N epsilon-diacetyl-L-lysyl-D-alanyl-D-alanine to water. It also performs a weak beta-lactamase activity, hydrolysing penicillin into penicilloate at a very low rate. This protein consists of 212 amino acid residues in a single polypeptide chain. The N terminus is partially blocked as a result of the cyclization of the dipeptide Asn-Gly into anhydroaspartylglycine imide. The protein has been fragmented by cyanogen bromide into five fragments whose sequences have been determined via appropriate subcleavages with various proteases. The ordering of the cyanogen bromide peptide fragments has been carried out (a) by submitting the S-carboxymethylated protein to complete tryptic digestion and labelling the methionine-containing peptides thus obtained with iodo[14C]-acetamide, and (b) by submitting to limited tryptic digestion the S-[2-(4'-pyridyl)ethyl]-cysteine protein whose amino groups have been blocked by reaction with exo-cis-3,6-endoxo-delta 4-tetrahydrophthalic anhydride prior to digestion. The protein contains six cysteine residues in the form of three disulfide bridges. No homology is found by comparing this peptidase with other Zn2+-containing enzymes (carboxypeptidase A, thermolysin, carbonic anhydrase B and alcohol dehydrogenase) and several completely or partially sequenced, serine-containing D-alanyl-D-alanine-cleaving peptidases and Zn2+/serine-containing beta-lactamases. [less ▲]

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