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The kinetics of the cytolytic activity expressed by lactoperoxidase and horseradish peroxidase toward erythrocytes in the presence of H2O2 and iodide have been investigated at physiological pH. The action of both enzymes was found to be very similar with respect to their kinetic mechanisms. Both enzymes showed saturation kinetics at higher enzyme concentrations under conditions where substrate concentrations were not limiting. Optimal concentrations of H2O2 and iodide were found to be 40 and 25 microM, respectively, for both enzymes. Higher concentrations of H2O2 inhibited the cytolytic activity. The pH dependence of the cytolytic reaction is also very similar for both enzymes, showing maximal activity at about pH 6.3. Moreover, the cytolytic activities of both enzymes were inhibited by tyrosine, tryptophan, cysteine, and to a lesser extent by histidine. We conclude from these data that the mechanisms of horseradish peroxidase and lactoperoxidase in promoting the lysis of erythrocytes are closely related if not identical.
S J McFaul, and
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J Everse
November 1986,
Biochimica et biophysica acta,
S J McFaul, and
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J Everse
January 2016,
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S J McFaul, and
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J Everse
August 1993,
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S J McFaul, and
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J Everse
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S J McFaul, and
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Chemico-biological interactions,
S J McFaul, and
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Archives of biochemistry and biophysics,
S J McFaul, and
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S J McFaul, and
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J Everse
December 1998,
Indian journal of biochemistry & biophysics,
S J McFaul, and
H Lin, and
J Everse
January 1987,
Biofizika,
S J McFaul, and
H Lin, and
J Everse
October 1991,
The Biochemical journal,
