FURTHER OBSERVATIONS ON CHEMICAL NATURE OF RUBREDOXIN FROM CLOSTRIDIUM PASTEURIANUM

The nature of the iron binding of rubredoxin undoubtedly accounts for the redox properties of the protein. The half-cysteine residues in the protein appear to form four of the ligands of the iron. This conclusion was derived from measuring the reactivity of the protein toward sulfhydryl reagents (iodoacetate and mercurials) and the finding that 2-mercaptoethanol was required for an69Fe exchange reaction and for reconstitution of the apoprotein. It was also observed that rubredoxin could undergo its complete redox cycle in the crystalline state without apparent damage to the crystal. Finally, an improved technique for the isolation of rubredoxin from Clostridium pasteurianum is described. © 1969, American Chemical Society. All rights reserved.