title: Hemin-mediated oxidative degradation of proteins.
abstract: Hemin, in the presence of 2-mercaptoethanol and oxygen, catalyzes the selective degradation of heme-binding proteins to small peptide fragments. Among the proteins examined, the heme-binding protein of rabbit serum (HBP-93) proved to be unusually sensitive. Myoglobin also exhibited considerable sensitivity whereas hemopexin and bovine serum albumin were only slightly susceptible to this degradative action of hemin. The reaction with HBP-93 depended upon coordination of the protein with hemin, was optimal at pH 6.5 and increased 4-fold as the temperature was elevated from 10 to 60 degrees C. The requirement for both oxygen and the reducing agent, 2-mercaptoethanol, and the partial protection of HBP-93 to degradation by catalase, superoxide dismutase, mannitol, and thiourea suggest the involvement of reduced oxygen species in the reaction. A possible role for the heme-mediated degradation of proteins in cell differentiation and other biological responses is discussed.
mesh_terms: D000818:Animals; D002352:Carrier Proteins; D002417:Cattle; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D006418:Heme / Q000031:analogs & derivatives*; D000081062:Heme-Binding Proteins; D006420:Hemeproteins; D006427:Hemin / Q000378:metabolism* / Q000031:analogs & derivatives; D006861:Hydrogen Peroxide / Q000378:metabolism; D008623:Mercaptoethanol / Q000378:metabolism; D008970:Molecular Weight; D010100:Oxygen / Q000378:metabolism; D012685:Sepharose / Q000031:analogs & derivatives / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D013696:Temperature
chemical_list: D002352:Carrier Proteins; D000081062:Heme-Binding Proteins; D006420:Hemeproteins; C034982:hemin-sepharose; D013481:Superoxides; D006418:Heme; D008623:Mercaptoethanol; D006427:Hemin; D012685:Sepharose; D006861:Hydrogen Peroxide; D005954:Glucosephosphate Dehydrogenase; D005980:Glutathione Reductase; D010100:Oxygen