Crystallization and preliminary x-ray diffraction analysis of P450(terp) and the hemoprotein domain of P450(BM-3), enzymes belonging to two distinct classes of the cytochrome P450 superfamily

Cytochromes P450 are members of a superfamily of hemoproteins that are involved in the metabolism of various physiologic and xenobiotic organic compounds. This superfamily of proteins can be divided into two classes based on the electron donor proximal to the P450: an iron-sulfur protein for class I P450s or a flavoprotein for class II. The only known tertiary structure of any of the cytochromes P450 is that of P450(cam), a class I soluble enzyme isolated from Pseudomonas putida (product of the CYP101 gene). To understand the details of the structure-function relationships within and between the two classes, structural studies on additional cytochromes P450 are crucial. We report here characterization of the crystal forms of two soluble, bacterial enzymes: cytochrome P450(terp) [class I enzyme from a Pseudomonas species (product of CYP108 gene)] and the hemoprotein domain of cytochrome P450(BM-3) [class II enzyme from Bacillus megaterium (product of the CYP102 gene)]. The crystals of cytochrome P450(terp) are hexagonal and belong to the space group P6₁22 (or its enantiomorph, P6₅22) with unit cell dimensions a = b = 68.9 Å and c = 458.7 Å. The crystals of the hemoprotein domain of cytochrome P450(BM-3) are monoclinic and belong to the space group P2₁ with unit cell dimensions a = 59.4 Å, b = 154.0 Å, c = 62.2 Å, and β = 94.7°. Diffraction data for the crystals of these two proteins were obtained to a resolution better than 2.2 Å. Assuming the presence of two molecules in the asymmetric unit for the hemoprotein domain of P450(BM-3) and one molecule for P450(terp), the calculated values of V(m) are 2.6 and 3.3 ų/Da, respectively.