Oxidation of human and animal haemoglobins with ascorbate, acetylphenylhydrazine, nitrite, and hydrogen peroxide

Partially purified haemoglobin solutions of man, horse, car and dog were oxidized with ascorbate, acetylphenylhydrazine, nitrite, and H2O2 at 25 degrees C and with ascorbate and acetylphenylhydrazine at 37 degrees C. Haemoglobins of the carnivores were more easily oxidized with ascorbate, nitrite, and H2O2 than equine and human haemoglobins. Feline haemoglobin, in general, appeared more susceptible to oxidation, particularly oxidative denaturation, than those of the other species. In addition, results of the incubations at 37 degrees C suggest that feline haemoglobin B might be more susceptible to oxidative denaturation than feline haemoglobin A. Equine haemoglobins appeared to be the least susceptible to oxidation with ascorbate and nitrite, but were more easily oxidized with acetylphenylhydrazine than those of the dog or man. It is apparent, therefore, that because a haemoglobin is more susceptible to oxidation with one oxidant does not mean that it will be more susceptible to oxidation with all oxidants. Results from the present study support the concept that an oxidant intermediate(s) is more important than H2O2 in drug-mediated oxidation of haemoglobin.