Peroxidase activity of erythrocytes hemoglobin under action of low-frequency vibration

Abstract

Background. Hemoglobin is a hemoprotein which in the presence of oxidative equivalents, such as H2O2, can act as peroxidase with a very high oxidative potential. Hemoglobin oxidation is accompanied by generation of highly oxidized forms of iron and globin radicals that have high oxidative activity and are toxic to cells. In addition, peroxidase activity may indicate structural changes that occur in the hemoglobin molecule as a result of chemical modification. Materials and Methods. Erythrocyte suspension was subjected to vibration for 3 h within the frequency range from 8 to 32 Hz with amplitudes of 0.5 ± 0.04 and 0.9 ± 0.08 mm. At certain intervals, hemoglobin peroxidase activity was determined together with the content of its ligand forms in the hemolysates of cells. Additionally, experiments were performed to investigate the mechanism and calculate the kinetic parameters of peroxidase reaction. Results and Discussion. Experimental data on low-frequency vibrations effect on erythrocyte hemoglobin peroxidase activity were analyzed. The kinetics of the oxidation reaction of p-phenylenediamine by hemoglobin in erythrocytes was studied. It was found that peroxidase oxidation has a ping-pong mechanism. The kinetic parameters of the peroxidase reaction involving hemoglobin were determined. The change of kinetic parameters after two-hour exposure to the incubation medium and low-frequency vibration was studied. A possible mechanism of action of hemoglobin in oxidation reactions involving H2O2 was proposed. Conclusion. Any effect that initiates the formation of methemoglobin leads to an increase in the peroxidase activity of hemoglobin due to the involvement of the latter in the pseudoperoxidase cycle and the formation of toxic reactive globin radicals. The high content of oxyhemoglobin in the cell, observed under vibrations within the frequency range of 16–32 Hz with an amplitude of 0.9 ± 0.08 mm, can prevent its oxidation and involvement in the pseudoperoxidase cycle.