Liposome oxidation and erythrocyte lysis by enzymically generated superoxide and hydrogen peroxide.

Publisher Summary Hemoglobin readily undergoes one-electron oxidations and reductions, and it can act as a source or sink of free radicals An autoxidation of the heme groups produces O2– and, indirectly, H2O2 Hemoglobin also interacts with redox-active xenobiotics and metabolites, forming the xenobiotic radical and initiating a series of reactions that generate other radicals and oxidant species and often result in oxidative denaturation of the hemoglobin This chapter focuses on the measurement of oxidant-mediated changes to hemoglobin It defines the different oxidation products of hemoglobin and briefly describes general mechanisms for their production The oxidation of oxyhemoglobin (oxyHb)4 gives O2– and methemoglobin (metHb) If the globin structure is destabilized, metHb can convert to hemichrome in which either the distal histidine or an external ligand occupies the sixth coordination position of the ferric heme Hemichromes precipitate readily and are the main constituent of Heinz bodies Choleglobin is a term used to describe denatured hemoglobin in which the porphyrin ring has been hydroxylated or broken open Ferrylhemoglobin (ferrylHb or Hb2+H2O2) is an Fe(IV) complex formed from ferrous hemoglobin and H2O2 The reaction of metHb with H2O2 produces short-lived ferryl radicals, which are Fe (IV) species with the additional oxidizing equivalent localized on the globin

Oxidative reactions of hemoglobin.

Mechanisms of autoxidation of hemoglobin, and its reactions with H2O2, O2-, and oxidizing or reducing xenobiotics are discussed. Reactive intermediates of such reactions can include drug free radicals, H2O2, and O2-, as well as peroxidatively active ferrylhemoglobin and methemoglobin-H2O2. The contributions of these species to hemoglobin denaturation and drug-induced hemolysis, and the actions of various protective agents, are considered.

https://www.jstor.org/stable/info/3430020

Free-radical production and oxidative reactions of hemoglobin

Phenol and catechol induce prehemolytic and hemolytic changes in human erythrocytes

Neutrophil-mediated methemoglobin formation in the erythrocyte. The role of superoxide and hydrogen peroxide.

The rate of oxidation by hydrogen peroxide of human hemoglobin, virtually free from catalase, glutathione peroxidase, and superoxide dismutase, was found to be proportional to the concentrations of hemoglobin and hydrogen peroxide, the second-order rate constant at pH 7.4 and 37° being k = 125 M-1 sec-1. Formation of ferrihemoglobin by reduced glutathione in air was found to be slow, gaining its maximal velocity after a lag phase. Kinetic data and the effect of catalase or glutathione peroxidase demonstrated that hydrogen peroxide is an essential intermediate which produces ferrihemoglobin in solutions of hemoglobin and reduced glutathione. The much higher rate of ferrihemoglobin formation by phenylhydroxylamine than by hydrogen peroxide and the failure of catalase to inhibit the reaction showed that hydrogen peroxide is not an important intermediate in the formation of ferrihemoglobin by phenylhydroxylamine. The reaction rate was found to be proportional to the concentrations of phenylhydroxylamine and hemoglobin. The second-order rate constant was calculated to be k = 2350 M-1 sec-1. With the formation of ferrihemoglobin by 4-dimethylaminophenol also, reaction rates and the failure of catalase to inhibit the reaction demonstrated that hydrogen peroxide is of no importance. The lag phase of the reaction suggests that oxidation products of 4-dimethylaminophenol produced by the reaction between oxyhemoglobin and 4-dimethylaminophenol are essential intermediates.

G. Klein

Papers

Kinetics of ferrihemoglobin formation by some reducing agents, and the role of hydrogen peroxide.