1aln

CRYSTAL STRUCTURE OF CYTIDINE DEAMINASE COMPLEXED WITH 3-DEAZACYTIDINE

spinqualitylabelsall models 1aln, resolution 2.30Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1aln is a 1 chain structure with sequence from Escherichia coli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.3Å Ligands: CTD, ZN Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function CDD_ECOLI This enzyme scavenges exogenous and endogenous cytidine and 2'-deoxycytidine for UMP synthesis. 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 cytidine deaminase substrate analog inhibitor 3-deazacytidine binds with its 4-amino group inserted into a site previously identified as a probable binding site for the leaving ammonia group. Binding to this site shifts the pyrimidine ring significantly further from the activated water molecule than the position it occupies in either of two complexes with compounds capable of hydrogen bonding at the 3-position of the ring [Xiang et al. (1995) Biochemistry 34, 4516-4523]. Difference Fourier maps between the deazacytidine, dihydrozebularine, and zebularine--hydrate inhibitor complexes suggest that the ring itself moves successively toward the activated water, leaving the amino group behind in this site as the substrate complex approaches the transition state. They also reveal systematic changes in a single zinc-sulfur bond distance. These correlate with chemical changes expected as the substrate approaches the tetrahedral transition state, in which the zinc-activated hydroxyl group develops maximal negative charge and forms a short hydrogen bond to the neighboring carboxylate group of Glu 104. Empirical bond valence relationships suggest that the Zn-S gamma 132 bond functions throughout the reaction as a "valence buffer" that accommodates changing negative charge on the hydroxyl group. Similar structural features in alcohol dehydrogenase suggest that analogous mechanisms may be a general feature of catalysis by zinc enzymes. Cytidine deaminase complexed to 3-deazacytidine: a "valence buffer" in zinc enzyme catalysis.,Xiang S, Short SA, Wolfenden R, Carter CW Jr Biochemistry. 1996 Feb 6;35(5):1335-41. PMID:8634261 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Deaminase 3D structures

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