3.2.2.8 - 654131 3.2.2.8 crystal structure is determined at 1.6 A resolution. The enzyme is crystallized using the hanging drop vapor diffusion method by mixing an equal amount of protein and a precipitant solution, composed of 100 mM bicine (pH 9) and 1.5 M ammonium sulfate 724342 3.2.2.8 hanging drop vapor diffusion method 657373 3.2.2.8 hanging drop vapour diffusion method, using 100 mM Tris (pH 8.5), 200 mM NaCl, and 24% PEG 4000 696258 3.2.2.8 molecular dynamics simulation. Both in wild-type and mutant T223Y/Q227Y, inosine binding is facilitated by interactions of the ribose moiety with active site residues and Ca2+, and pi-interactions between residues His82 and His239 and the nucleobase. The lack of observed activity toward inosine for wild-type CU-NH is explained by no residue being correctly aligned to stabilize the departing nucleobase. A hydrogen-bonding network between hypoxanthine and a general acid Asp15 is present when the two Tyr mutations are engineered into the active site. This hydrogen-bonding network is only maintained when both Tyr mutations are present due to a pi-interaction between the residues 751203 3.2.2.8 purified detagged recombinant enzyme, hanging drop vapour diffusion method, 10 mg/ml protein in 20 mM HEPES, pH 7.4, 150 mM NaCl, is mixed with precipitant solution, 25°C, equilibration versus reservoir solution containing 100 mM Tris-HCl, pH 8.5, 200 mM NaCl, 25% w/v PEG 3350, cryoprotection by 25% glycerol, X-ray diffraction structure determination and analysis at 1.7 A resolution 663495 3.2.2.8 purified recombinant enzyme in complex with D-ribose, hanging drop vapour diffusion method, 10 mg/ml protein in 10 mM Tris, pH 7.0, 25 mM NaCl, and 500 mM D-ribose, is mixed with an equal volume of precipitant solution containing 24% 2-methyl-2,4-pentanediol, 0.1 M sodium acetate, pH 5.0, and 500 mM D-ribose, 20°C, 1 week, X-ray diffraction structure determination and analysis at 1.78 A resolution 664140 3.2.2.8 QM/MM simulations. The relatively stronger hydrogen-bond interactions between uridine and the active-site residues Gln227 and Tyr231 play an important role in enhancing the substrate binding and thus promoting the N-glycosidic bond cleavage, in comparison with inosine. The estimated energy barrier is 30 kcal/mol for the hydrolysis of inosine and 22 kcal/mol for uridine. The uridine binding is exothermic by about 23 kcal/mol, and inosine binding by 12 kcal/mol 751391 3.2.2.8 RihA bound to inhibitor 3,4-diaminophenyl-D-iminoribitol, hanging drop vapour diffusion method, 8 mg/ml RihA in 50 mM HEPES, pH 7.2, 150 mM NaCl is mixed with a 5:1 molar excess of 3,4-diaminophenyl-D-iminoribitol, solubilized in 50 mM HEPES, pH 7.2, and incubated at 4°C for 3 hours, the protein/inhibitor complex is mixed with an equal volume of a precipitant solution containing 25% PEG 4000, 0.1 M sodium acetate, pH 5.0, X-ray diffraction structure determination and analysis at 2.1 A resolution, molecular replacement 707897 3.2.2.8 to 1.53 A resolution, orthorhombic space group I222 752168