title: Dioxygen and the vitamin K-dependent synthesis of prothrombin.
abstract: It has been shown that bovine erythrocyte superoxide dismutase inhibits the gamma-carboxylation of glutamyl residues in the precursor of prothrombin and in a related synthetic peptide by a vitamin K-dependent rat liver microsomal carboxylase. In the same conditions a simple copper(II) tyrosinyl complex also inhibits the carobxylation. The formation of the vitamin K epoxide by the same systems is inhibited by both superoxide dismutase and catalase. It is suggested that the formation of the epoxide is a process distinct from carboxylation, representing perhaps a protective mechanism against the superoxide ion, or species derived therefrom, generated by the reaction of reduced vitamin K with dioxygen. Furthermore, the possibility that the carboxylating species is formed by the reaction of the superoxide ion, or species derived therefrom, with carbon dioxide, is proposed.
mesh_terms: D000818:Animals; D002374:Catalase / Q000378:metabolism; D004852:Epoxy Compounds; D008862:Microsomes, Liver / Q000378:metabolism; D010084:Oxidation-Reduction; D010100:Oxygen / Q000502:physiology*; D010545:Peroxides; D011516:Prothrombin / Q000096:biosynthesis*; D051381:Rats; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000502:physiology; D014812:Vitamin K / Q000378:metabolism*
chemical_list: D004852:Epoxy Compounds; D010545:Peroxides; D013481:Superoxides; D014812:Vitamin K; D011516:Prothrombin; D002374:Catalase; D013482:Superoxide Dismutase; D010100:Oxygen