Crystallization and preliminary X-ray analysis of cholesterol oxidase from Brevibacterium sterolicum containing covalently bound FAD.

Single crystals of cholesterol oxidase from Brevibacterium sterolicum containing a covalently bound form of the FAD cofactor have been obtained. The crystals are grown by vapor diffusion using the hanging drop technique from 12% polyethylene glycol, Mr 8000, and 75 mM MnSO4 as the precipitant at pH 5.2. In order to obtain large diffraction quality crystals, nucleation must occur at 22 degrees C with subsequent growth at 17 degrees C. The crystals belong to the monoclinic space group P21 with cell dimensions a = 78. 5 A, b = 126.7 A, c = 82.4 A and beta = 108.9 degrees with two protein molecules per asymmetric unit. Diffraction of these crystals has been observed to at least 2.2 A resolution and they are suitable for an X-ray structure analysis.