Article (Scientific journals)
Effects of thiol reagents on Streptomyces K15 DD-peptidase-catalysed reactions
Leyh-Bouille, Mélina; Nguyen-Distèche, Martine; Bellefroid-Bourguignon, Catherine et al.
1987In Biochemical Journal, 241 (3), p. 893-897
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Keywords :
chloromercuribenzoates/pharmacology; dithionitrobenzoic acid/pharmacology; hydrolysis; kinetics; muramoylpentapeptide carboxypeptidase/antagonists & inhibitors/*metabolism; penicillin g/pharmacology; streptomyces/*enzymology; sulfhydryl compounds/*pharmacology; p-chloromercuribenzoic acid
Abstract :
[en] The 26,000-Mr DD-peptidase of Streptomyces K15 binds one equivalent of thiol reagents as 5,5'-dithiobis-(2-nitrobenzoate) or p-chloromercuribenzoate (pCMB). Derivatization of the DD-peptidase by pCMB decreases the efficacy of the initial binding of the ester carbonyl donor Ac2-L-Lys-D-Ala-D-lactate to the enzyme (K), the rate of enzyme acylation by the donor (K+2) and the rate of enzyme deacylation (k+3). However, the value of the k+2/k+3 ratio, and therefore the percentage of total enzyme which, at saturating concentrations of the donor, is present as acyl-enzyme at the steady state of the reaction, are not modified. The enzyme's binding sites for pCMB and benzylpenicillin are not mutually exclusive. But, when compared with the native enzyme, the pCMB-derivatized enzyme undergoes acylation by benzylpenicillin with a decreased second-order-rate constant (k+2/K) value and gives rise to a penicilloyl adduct of increased stability. Since the acyl-enzyme mechanism is not annihilated by pCMB derivatization, it is proposed that basically, and like all the other DD-peptidases/penicillin-binding proteins so far characterized, the Streptomyces K15 DD-peptidase is an active-site-serine enzyme.
Disciplines :
Microbiology
Biochemistry, biophysics & molecular biology
Author, co-author :
Leyh-Bouille, Mélina;  Université de Liège - ULiège > Institut de Chimie > Service de Microbiologie
Nguyen-Distèche, Martine ;  Université de Liège - ULiège > Institut de Chimie > Service de Microbiologie
Bellefroid-Bourguignon, Catherine;  Université de Liège - ULiège > Institut de Chimie > Service de Microbiologie
Ghuysen, Jean-Marie ;  Université de Liège - ULiège > Institut de Chimie > Service de Microbiologie
Language :
English
Title :
Effects of thiol reagents on Streptomyces K15 DD-peptidase-catalysed reactions
Publication date :
01 February 1987
Journal title :
Biochemical Journal
ISSN :
0264-6021
eISSN :
1470-8728
Publisher :
Portland Press, London, United Kingdom
Volume :
241
Issue :
3
Pages :
893-897
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
since 07 January 2011

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