title: The molecular weight of, and evidence for two types of subunits in, the molybdenum-iron protein of Azotobacter vinelandii nitrogenase.
abstract: The weight-average molecular weight of the Mo-Fe protein isolated from Azotobacter vinelandii has been determined by sedimentation-equilibrium techniques. In buffer, the value is 245000+/-5000; in  8M-urea, the value is 61000+/-1000. The protein was separated into two components by chromatography on CM-cellulose in 7M-urea, pH 4.5. These components have similar molecular weights but were shown to differ in charge, amino acid content and arginine-containing peptides. It is proposed that the tetramer has the subunit composition (nalpha2nbeta2).
mesh_terms: D000596:Amino Acids / Q000032:analysis; D001395:Azotobacter / Q000201:enzymology*; D002845:Chromatography; D005288:Ferredoxins / Q000032:analysis*; D008970:Molecular Weight; D008983:Molybdoferredoxin / Q000032:analysis*; D009591:Nitrogenase; D014461:Ultracentrifugation
chemical_list: D000596:Amino Acids; D005288:Ferredoxins; D008983:Molybdoferredoxin; D009591:Nitrogenase