Characteristics and crystallization of nitrogenase MoFe protein from a nif Z deleted strain of Azotobacter vinelandii

Delta nif Z MoFe protein purified from a nif Z deleted strain of Azotobacter vinelandii (DJ194) was shown to be pure by SDS-Polyacrylamide gel electrophoresis. The protein contained 1.5 Mo atoms and 15.9 Fe atoms per molecule, the ratio of Fe to Mo was lower than that of the MoFe protein purified from the wild type strain of A. vinelandii; and C(2)H(2), H(+)-reduction activity and their ratio (C(2)H(4)/H(2)(Ar)) were 16.6%, 21.7% and 77.2% of those of the wild type MoFe protein, respectively. Under a somewhat different condition from that for the crystallization of the wild type MoFe protein dark brown rhombohedron crystals of Delta nifZ MoFe protein were obtained. It indicated that the deletion of the nif Z resulted in the decrease of number or change in the structure of P-cluster in the mutant MoFe protein, which caused the significant structured and function of change of the protein.