A hemoprotein from azotobacter containing non-heme iron: isolation and crystallization

A new type of hemoprotein was isolated from extracts of $\text{Azotobacter vinelandii}$ using a heat step, application of the protamine-cellulose phosphate procedure, and precipitation with MgCl₂. Crystallization was achieved using low concentration of MgCl₂. The protein was shown to be a unique cytochrome of the b type containing up to 20% non-heme iron but no “acid labile sulfur”. Both the heme and non-heme iron appear to be functional redox components.