Abstract
Preliminary X-ray diffraction data from single crystals of the MoFe proteins of nitrogenase from C. pasteurianum and A. vinelandii were obtained. Both protein crystals belong to the P21 space group. The MoFe protein crystals from C. pasteurianum and A. vinelandii diffract to angles corresponding to resolutions as great as 2.4 and 3.0 .ANG., respectively. The cell dimensions of the MoFe protein crystals from the 2 spp. were determined from precession photographs.