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| {{STRUCTURE_1hzo| PDB=1hzo | SCENE= }} | | {{STRUCTURE_1hzo| PDB=1hzo | SCENE= }} |
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| '''STRUCTURE OF CLASS A CEPHALOSPORINASE FROM PROTEUS VULGARIS K1'''
| | ===STRUCTURE OF CLASS A CEPHALOSPORINASE FROM PROTEUS VULGARIS K1=== |
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| ==Overview==
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| The structure of a chromosomal extended-spectrum beta-lactamase (ESBL) having the ability to hydrolyze cephalosporins including cefuroxime and ceftazidime has been determined by X-ray crystallography to 1.75 A resolution. The species-specific class A beta-lactamase from Proteus vulgaris K1 was crystallized at pH 6.25 and its structure solved by molecular replacement. Refinement of the model resulted in crystallographic R and R(free) of 16.9 % and 19.3 %, respectively. The folding of the K1 enzyme is broadly similar to that of non-ESBL TEM-type beta-lactamases (2 A rmsd for C(alpha)) and differs by only 0.35 A for all atoms of six conserved residues in the catalytic site. Other residues promoting extended-spectrum activity in K1 include the side-chains of atypical residues Ser237 and Lys276. These side-chains are linked by two water molecules, one of which lies in the position normally filled by the guanidinium group of Arg244, present in most non-ESBL enzymes but absent from K1. The ammonium group of Lys276, ca 3.5 A from the virtual Arg244 guanidinium position, may interact with polar R2 substitutents on the dihydrothiazene ring of cephalosporins. | | The line below this paragraph, {{ABSTRACT_PUBMED_11916382}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 11916382 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_11916382}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Hydrolase]] | | [[Category: Hydrolase]] |
| [[Category: Mixed alpha/beta]] | | [[Category: Mixed alpha/beta]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 19:24:14 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 10:11:29 2008'' |
