Reference : Effects of thiol reagents on Streptomyces K15 DD-peptidase-catalysed reactions
Scientific journals : Article
Life sciences : Biochemistry, biophysics & molecular biology
Life sciences : Microbiology
http://hdl.handle.net/2268/81291
Effects of thiol reagents on Streptomyces K15 DD-peptidase-catalysed reactions
English
Leyh-Bouille, Mélina [Université de Liège - ULg > Institut de Chimie > Service de Microbiologie > >]
Nguyen-Distèche, Martine mailto [Université de Liège - ULg > Institut de Chimie > Service de Microbiologie > >]
Bellefroid-Bourguignon, Catherine [Université de Liège - ULg > Institut de Chimie > Service de Microbiologie > >]
Ghuysen, Jean-Marie [Université de Liège - ULg > Institut de Chimie > Service de Microbiologie > >]
1-Feb-1987
Biochemical Journal
Portland Press
241
3
893-897
Yes (verified by ORBi)
International
0264-6021
1470-8728
London
United Kingdom
[en] chloromercuribenzoates/pharmacology ; dithionitrobenzoic acid/pharmacology ; hydrolysis ; kinetics ; muramoylpentapeptide carboxypeptidase/antagonists & inhibitors/*metabolism ; penicillin g/pharmacology ; streptomyces/*enzymology ; sulfhydryl compounds/*pharmacology ; p-chloromercuribenzoic acid
[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.
Researchers ; Professionals
http://hdl.handle.net/2268/81291

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