Crystallization and preliminary analysis of active nitroalkane oxidase in three crystal forms.

Nitroalkane oxidase (NAO), a flavoprotein cloned and purified from Fusarium oxysporum, catalyzes the oxidation of neutral nitroalkanes to the corresponding aldehydes or ketones, with the production of H2O2 and nitrite. In this paper, the crystallization and preliminary X-ray data analysis of three crystal forms of active nitroalkane oxidase are described. The first crystal form belongs to a trigonal space group (either P3(1)21 or P3(2)21, with unit-cell parameters a = b = 103.8, c = 487.0 A) and diffracts to at least 1.6 A resolution. Several data sets were collected using 2theta and kappa geometry in order to obtain a complete data set to 2.07 A resolution. Solvent-content and Matthews coefficient analysis suggests that crystal form 1 contains two homotetramers per asymmetric unit. Crystal form 2 (P2(1)2(1)2(1); a = 147.3, b = 153.5, c = 169.5 A) and crystal form 3 (P3(1) or P3(2); a = b = 108.9, c = 342.5 A) are obtained from slightly different conditions and also contain two homotetramers per asymmetric unit, but have different solvent contents. A three-wavelength MAD data set was collected from selenomethionine-enriched NAO (SeMet-NAO) in crystal form 3 and will be used for phasing.