EC Number |
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5.3.3.1 | - |
5.3.3.1 | 1.2-1.5 A resolution X-ray crystallography, 1H and 19F NMR spectroscopy, quantum mechanical calculations, and transition-state analogue binding measurements of the active site. Packing and binding interactions within the KSI active site can constrain local side-chain reorientation and prevent hydrogen bond shortening by 0.1 A or less. This constraint has substantial energetic effects on ligand binding and stabilization of negative charge within the oxyanion hole. Structural features of the oxyanion hole suggest that hydrogen bond formation to the reacting substrate is geometrically optimal in the transition state but not in the ground state. During steroid isomerization, the hybridization of the substrate oxygen changes from a planar sp2 carbonyl to a tetrahedral sp3 dienolate, altering the spatial distribution of its lone pair electrons. This reorientation of atomic orbitals about the substrate oxygen alters its geometric preference for accepting hydrogen bonds |
5.3.3.1 | crystal structure of mutant enzyme F82A is determined to 2.1 A resolution. Crystals are grown in a solution containing 1.0 M sodium acetate and 0.1 M ammonioum acetate, pH 4.6, by the hanging drop method of vapor diffusion at 22 C. The crystals belong to the space group c2221 with unit cell dimensions of a = 36.24 A, b = 96.13 A and c = 74.30 A |
5.3.3.1 | crystal structure of the enzyme in complex with equilenin, an analogue of the reaction intermediate at 1.9 and 2.5 A resolution |
5.3.3.1 | crystal structure of the R72A mutant enzyme determined at 2.5 A resolution belongs to the space group C2221 with cell dimensions of a = 36.37 A, b = 74.44 A and c = 96.06 A. Crystals are grown from a solution containing 2.0 M ammonioum acetate and 0.1 M sodium acetate at pH 4.6 by hanging drop vapor-diffusion method at 22°C |
5.3.3.1 | crystals are grown at 12°C from1.3 M ammonium sulfate, 3-5% poly(ethylene glycol)400 and 0.1 M HEPES, pH 7.5 in hanging drops. The crystal structure at 2.3 resolution reveals that the active site environment of the Comamonas testosteroni enzyme is nearly identical to that of Pseudomonas putida enzyme |
5.3.3.1 | crystals of mutant enzyme F116W are grown by hanging-drop method |
5.3.3.1 | crystals of Y30F, Y55F, and Y30F/Y55F are grown in the solution containing 1.0 M sodium acetate and 0.1 M ammonium acetate, pH 4.6 by hanging drop method of vapor diffusion at 22°C. The crystal structure of Y55F as determined at 1.9 A resolution shows that Tyr14 OH undergoes an alteration in orientation to form a new hydrogen bond with Tyr30 |
5.3.3.1 | enzyme mutant D40N bound to phenolate, X-ray diffraction structure determination and analysis at 1.25 A resolution |
5.3.3.1 | GST A3-3 in complex with DELTA5-androstene-3,17-dione, using 100 mM Tris-HCl pH 7.8, 18% (v/v) PEG 4000, and 2 mM dithiothreitol |