3uax

Crystal structure of adenosine phosphorylase from Bacillus cereus complexed with inosine

spinqualitylabelsall models 3uax, resolution 1.20Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3uax is a 1 chain structure with sequence from Atcc 14579. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: GOL, NOS, SO4 Related: 3uav, 3uaw, 3uay, 3uaz Gene: deoD (ATCC 14579) Activity: Purine-nucleoside phosphorylase, with EC number 2.4.2.1 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed Purine nucleoside phosphorylases catalyze the phosphorolytic cleavage of the glycosidic bond of purine (2'-deoxy)nucleosides, generating the corresponding free base and (2'-deoxy)ribose 1-phosphate. Two classes of PNPs have been identified: homotrimers specific for 6-oxopurines and homohexamers that accept both 6-oxopurines and 6-aminopurines. Bacillus cereus adenosine phosphorylase (AdoP) is a hexameric PNP; however, it is highly specific for 6-aminopurines. To investigate the structural basis for the unique substrate specificity of AdoP, the active-site mutant D204N was prepared and kinetically characterized and the structures of the wild-type protein and the D204N mutant complexed with adenosine and sulfate or with inosine and sulfate were determined at high resolution (1.2-1.4 A). AdoP interacts directly with the preferred substrate through a hydrogen-bond donation from the catalytically important residue Asp204 to N7 of the purine base. Comparison with Escherichia coli PNP revealed a more optimal orientation of Asp204 towards N7 of adenosine and a more closed active site. When inosine is bound, two water molecules are interposed between Asp204 and the N7 and O6 atoms of the nucleoside, thus allowing the enzyme to find alternative but less efficient ways to stabilize the transition state. The mutation of Asp204 to asparagine led to a significant decrease in catalytic efficiency for adenosine without affecting the efficiency of inosine cleavage. Structural basis of the substrate specificity of Bacillus cereus adenosine phosphorylase.,Dessanti P, Zhang Y, Allegrini S, Tozzi MG, Sgarrella F, Ealick SE Acta Crystallogr D Biol Crystallogr. 2012 Mar;68(Pt 3):239-48. Epub 2012 Feb 14. PMID:22349225 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Purine nucleoside phosphorylase 3D structures

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