title: Purification and properties of paramagnetic protein from Clostridium pasteurianum W5.
abstract: The purification to homogeneity of the non-heme iron protein, sometimes referred to as either "red protein" or "paramagnetic protein", from Clostridium pasteurianum W5 extracts is described and its physicochemical properties studied. This paramagnetic protein (g= 1.94) has a molecular weight of about 25000 and contains two iron and two acid-labile sulfur atoms per mol of protein. Its midpoint potential at pH 7.5, as determined by electron paramagnetic resonance titration, is -300 mV. Optical circular dichroism and electron paramagnetic resonance spectra of the paramagnetic protein are similar to those of two iron-two acid-labile sulfur ferredoxins. The biochemical reduction of the purified protein was also studied.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D001395:Azotobacter / Q000032:analysis; D001426:Bacterial Proteins / Q000302:isolation & purification; D002942:Circular Dichroism; D003013:Clostridium / Q000032:analysis*; D004578:Electron Spin Resonance Spectroscopy; D004589:Electrophoresis, Disc; D005288:Ferredoxins; D007501:Iron / Q000032:analysis; D008280:Magnetics; D008970:Molecular Weight; D011199:Potentiometry; D011487:Protein Conformation; D013045:Species Specificity; D013053:Spectrophotometry; D013056:Spectrophotometry, Ultraviolet; D013455:Sulfur / Q000032:analysis
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; D005288:Ferredoxins; D013455:Sulfur; D007501:Iron