![]() Thiolester substrates of DD-peptidases and beta-lactamasesDamblon, Christian ; ; et alin Letters In Peptide Science (1995), 2(3-4), 212-216 With peptide substrates, the penicillin-sensitive DD-peptidases exhibit a strict specificity for D-Ala-D-Xaa C-termini. Only glycine is tolerated as the C-terminal residue, but with a significantly ... [more ▼] With peptide substrates, the penicillin-sensitive DD-peptidases exhibit a strict specificity for D-Ala-D-Xaa C-termini. Only glycine is tolerated as the C-terminal residue, but with a significantly decreased activity. These enzymes also hydrolyse various ester and thiolester analogues of their natural substrates. Some of the thiolesters whose C-terminal leaving group exhibited an L stereochemistry were significantly hydrolysed by some of the studied enzymes, particularly by the Actinomadura R39 DD-peptidase. By contrast, the strict specificity for a D residue in the penultimate position was fully retained. The same esters and thiolesters also behaved as substrates for beta-lactamases. In this case, thiolesters exhibiting L stereochemistry in the C-terminal position could also be hydrolysed, mainly by the class C and class D enzymes. But, more surprisingly, the class C Enterobacter cloacae P99 beta-lactamase also hydrolysed thiolesters containing an L residue in the penultimate position, sometimes more efficiently than the D isomer. [less ▲] Detailed reference viewed: 19 (1 ULg)![]() Breakdown of the stereospecificity of DD-peptidases and beta-lactamases with thiolester substrates.Damblon, Christian ; ; et alin Biochemical Journal (1995), 309 ( Pt 2) With peptide analogues of their natural substrates (the glycopeptide units of nascent peptidoglycan), the DD-peptidases exhibit a strict preference for D-Ala-D-Xaa C-termini. Gly is tolerated as the C ... [more ▼] With peptide analogues of their natural substrates (the glycopeptide units of nascent peptidoglycan), the DD-peptidases exhibit a strict preference for D-Ala-D-Xaa C-termini. Gly is tolerated as the C-terminal residue, but with a significantly decreased activity. These enzymes were also known to hydrolyse various ester and thiolester analogues of their natural substrates. Some thiolesters with a C-terminal leaving group that exhibited L stereochemistry were significantly hydrolysed by some of the enzymes, particularly the Actinomadura R39 DD-peptidase, but the strict specificity for a D residue in the penultimate position was fully retained. These esters and thiolesters also behave as substrates for beta-lactamases. In this case, thiolesters exhibiting L stereochemistry in the ultimate position could also be hydrolysed, mainly by the class-C and class-D enzymes. However, more surprisingly, the class-C Enterobacter cloacae P99 beta-lactamase also hydrolysed thiolesters containing an L residue in the penultimate position, sometimes with a higher efficiency than the D isomer. [less ▲] Detailed reference viewed: 6 (2 ULg) |
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