1cef
From Proteopedia
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==Overview== | ==Overview== | ||
| - | Two clinically-important beta-lactam antibiotics, cephalothin and | + | Two clinically-important beta-lactam antibiotics, cephalothin and cefotaxime, have been observed by X-ray crystallography bound to the reactive Ser62 of the D-alanyl-D-alanine carboxypeptidase/transpeptidase of Streptomyces sp. R61. Refinement of the two crystal structures produced R factors for 3 sigma (F) data of 0.166 (to 1.8 A) and 0.170 (to 2.0 A) for the cephalothin and cefotaxime complexes, respectively. In each complex, a water molecule is within 3.1 and 3.6 A of the acylated beta-lactam carbonyl carbon atom, but is poorly activated by active site residues for nucleophilic attack and deacylation. This apparent lack of good stereochemistry for facile hydrolysis is in accord with the long half-lives of cephalosporin intermediates in solution (20-40 h) and the efficacy of these beta-lactams as inhibitors of bacterial cell wall synthesis. Different hydrogen binding patterns of the two cephalosporins to Thr301 are consistent with the low cefotaxime affinity of an altered penicillin-binding protein, PBP-2x, reported in cefotaxime-resistant strains of Streptococcus pneumoniae, and with the ability of mutant class A beta-lactamases to hydrolyze third-generation cephalosporins. |
==About this Structure== | ==About this Structure== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Streptomyces sp.]] | [[Category: Streptomyces sp.]] | ||
| - | [[Category: Knox, J | + | [[Category: Knox, J R.]] |
| - | [[Category: Kuzin, A | + | [[Category: Kuzin, A P.]] |
[[Category: CEF]] | [[Category: CEF]] | ||
[[Category: d-amino acid peptidase]] | [[Category: d-amino acid peptidase]] | ||
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[[Category: penicillin target]] | [[Category: penicillin target]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:05:17 2008'' |
Revision as of 10:05, 21 February 2008
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CEFOTAXIME COMPLEXED WITH THE STREPTOMYCES R61 DD-PEPTIDASE
Overview
Two clinically-important beta-lactam antibiotics, cephalothin and cefotaxime, have been observed by X-ray crystallography bound to the reactive Ser62 of the D-alanyl-D-alanine carboxypeptidase/transpeptidase of Streptomyces sp. R61. Refinement of the two crystal structures produced R factors for 3 sigma (F) data of 0.166 (to 1.8 A) and 0.170 (to 2.0 A) for the cephalothin and cefotaxime complexes, respectively. In each complex, a water molecule is within 3.1 and 3.6 A of the acylated beta-lactam carbonyl carbon atom, but is poorly activated by active site residues for nucleophilic attack and deacylation. This apparent lack of good stereochemistry for facile hydrolysis is in accord with the long half-lives of cephalosporin intermediates in solution (20-40 h) and the efficacy of these beta-lactams as inhibitors of bacterial cell wall synthesis. Different hydrogen binding patterns of the two cephalosporins to Thr301 are consistent with the low cefotaxime affinity of an altered penicillin-binding protein, PBP-2x, reported in cefotaxime-resistant strains of Streptococcus pneumoniae, and with the ability of mutant class A beta-lactamases to hydrolyze third-generation cephalosporins.
About this Structure
1CEF is a Single protein structure of sequence from Streptomyces sp. with as ligand. Active as Serine-type D-Ala-D-Ala carboxypeptidase, with EC number 3.4.16.4 Known structural/functional Site: . Full crystallographic information is available from OCA.
Reference
Binding of cephalothin and cefotaxime to D-ala-D-ala-peptidase reveals a functional basis of a natural mutation in a low-affinity penicillin-binding protein and in extended-spectrum beta-lactamases., Kuzin AP, Liu H, Kelly JA, Knox JR, Biochemistry. 1995 Jul 25;34(29):9532-40. PMID:7626623
Page seeded by OCA on Thu Feb 21 12:05:17 2008
