Production of superoxide anion by N,N-bis(2-hydroxyethyl)-iminotris(hydroxymethyl)methane buffer during oxidation of oxyhemoglobin by nitrite and effect of inositol hexaphosphate on the oxidation.
Oxidation of oxyhemoglobin by nitrite is characterized by the presence of a lag phase followed by an autocatalysis. As reported previously (Kosaka, H., Imaizumi, K. and Tyuma, I. (1982) Biochim. Biophys. Acta 702, 237-241), in phosphate buffer nitrite produced an ESR signal at g 2.005 (hereafter referred to as the g 2 radical). The g 2 radical produced NO.2 from NO-2, then NO.2 oxidized oxyhemoglobin. Superoxide dismutase did not modify the oxidation. On the other hand in N,N-bis(2-hydroxyethyl)iminotris(hydroxymethyl)methane (bistris) buffer, superoxide dismutase markedly elongated the lag phase and accelerated the autocatalysis, indicating O-2 production. Bistris scavenged the g 2 radical. O-2 was generated by the reduction of O2 by a radical derived from bistris. Inositol hexaphosphate inhibited the oxidation by decreasing H2O2 production from oxyhemoglobin.
D002021:Buffers; D006441:Hemoglobin A / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D009573:Nitrites / Q000494:pharmacology*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism*; D010108:Oxyhemoglobins / Q000378:metabolism*; D010833:Phytic Acid / Q000494:pharmacology*; D013053:Spectrophotometry; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*; D014325:Tromethamine / Q000031:analogs & derivatives* / Q000494:pharmacology
D002021:Buffers; D009573:Nitrites; D010108:Oxyhemoglobins; D014325:Tromethamine; D013481:Superoxides; D010833:Phytic Acid; D006441:Hemoglobin A; C029774:oxyhemoglobin A; D013482:Superoxide Dismutase; C026272:Bistris; D010100:Oxygen