On the mechanism of hydrogen peroxide formation during precipitation of hemoglobin with perchloric acid.
During acid precipitation of hemoglobin, hydrogen peroxide is formed. The oxidant is generated from hemoglobin-bound as well as from physically dissolved oxygen, provided divalent hemoglobin-iron is present. The extent of hydrogen peroxide formation seems to be dependent on the precipitating reagent. From experiments on GSH oxidation during precipitation of red cells and from a literature survey formation of at least one second reactive oxygen species has to be assumed. Different reaction pathways for generating these oxidants during acid precipitation are discussed: Hydroperoxide which is probably liberated by proton catalysis may contribute to the observed oxidation reactions. At pH approximately 1 it rapidly disproportionates yielding oxygen and hydrogen peroxide, which might produce reactive oxidants with hemoglobin intermediates formed during precipitation. In addition a new hypothesis is presented explaining the ability of N-ethylmaleimide to inhibit GSH oxidation during precipitation of red cells. Accordingly, the SH-reagent rapidly penetrates the cell membrane and reacts with GSH before access of protons prevents alkylation.
Gallemann
D
D
Walther-Straub-Institut für Pharmakologie und Toxikologie, Ludwig-Maximilians-Universität München.
Eyer
P
P
D011232:Chemical Precipitation; D005978:Glutathione / Q000378:metabolism; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D010472:Perchlorates / Q000494:pharmacology*
D006454:Hemoglobins; D010472:Perchlorates; D006861:Hydrogen Peroxide; D005978:Glutathione; D010100:Oxygen