VISIBLE CHEMILUMINESCENCE ASSOCIATED WITH THE REACTION BETWEEN METHEMOGLOBIN OR OXYHEMOGLOBIN WITH HYDROGEN-PEROXIDE

Visible chemiluminescence is emitted in the irreversible deactivation of hemoglobin or methemoglobin with excess H2O2. The emission takes pl ace in two phases. The most intense one lasts a few seconds and is fol lowed by a second phase of lower intensity that remains for longer per iods. This second phase presents chaotic or sustained oscillations. Fr ee radicals are implicated in the luminescent process since the emissi on can be reduced by free radical scavengers such as 6-hydroxy-2,5,7,8 ,-tetramethylchroman-2-carboxylic acid (Trolox) or ascorbic acid. Thes e additives lead to a delay in reaching the maximum intensity, which c an be related to their consumption, implying substantial recycling of the hemoprotein. Chemiluminescence is also observed in the oxidation o f hemin by H2O2, suggesting a role for the heme group in the processes leading to the excited state production. The lower intensity observed in the presence of hemin can be related to the contribution of the gl obin chains.