2znb

METALLO-BETA-LACTAMASE (CADMIUM-BOUND FORM)

spinqualitylabelsall models 2znb, resolution 2.15Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2znb is a 2 chain structure with sequence from Bacteroides fragilis. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CD, NA Gene: CCRA3 (WITHOUT SIGNAL SEQUENCE) (Bacteroides fragilis) Activity: Beta-lactamase, with EC number 3.5.2.6 Resources: FirstGlance, OCA, RCSB, PDBsum Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed The metallo-beta-lactamases require zinc or cadmium for hydrolyzing beta-lactam antibiotics and are inhibited by mercurial compounds. To data, there are no clinically useful inhibitors of this class of enzymes. The crystal structure of the Zn(2+)-bound enzyme from Bacteroides fragilis contains a binuclear zinc center in the active site. A hydroxide, coordinated to both zinc atoms, is proposed as the moiety that mounts the nucleophilic attack on the carbonyl carbon atom of the beta-lactam ring. To study the metal coordination further, the crystal structures of a Cd(2+)-bound enzyme and of an Hg(2+)-soaked zinc-containing enzyme have been determined at 2.1 A and 2.7 A, respectively. Given the diffraction resolution, the Cd(2+)-bound enzyme exhibits the same active-site architecture as that of the Zn(2+)-bound enzyme, consistent with the fact that both forms are enzymatically active. The 10-fold reduction in activity of the Cd(2+)-bound molecule compared with the Zn(2+)-bound enzyme is attributed to fine differences in the charge distribution due to the difference in the ionic radii of the two metals. In contrast, in the Hg(2+)-bound structure, one of the zinc ions, Zn2, was ejected, and the other zinc ion, Zn1, remained in the same site as in the 2-Zn(2+)-bound structure. Instead of the ejected zinc, a mercury ion binds between Cys 104 and Cys 181, 4.8 A away from Zn1 and 3.9 A away from the site where Zn2 is located in the 2-Zn(2+)-bound molecule. The perturbed binuclear metal cluster explains the inactivation of the enzyme by mercury compounds. Crystal structures of the cadmium- and mercury-substituted metallo-beta-lactamase from Bacteroides fragilis.,Concha NO, Rasmussen BA, Bush K, Herzberg O Protein Sci. 1997 Dec;6(12):2671-6. PMID:9416622 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Beta-lactamase

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