Effect of Myeloperoxidase/Hydrogen Peroxide/Halide System on Thermal Gelation of Soluble Collaqen

Abstract

Effect of myeloperoxidase (MPO)/H202/halide system on thermal gelation of soluble collagen was examined to test the ability of the system to alter the structure of this structural protein using MPO prepared from human polymorphonuclear leukocytes. The gelation that occurred at 3rC was markedly inhibited when collagen treated with MPO, H202 and halides. The inhibition required the three components. All the halides except F- were effective as cofactors. The inhibition was prevented by 102 scavengers such as histidine and diazobicyclo(2,2,2)octane. With these findings it is confirmed that the inhibition of collagen gelation was caused by MPO-mediated peroxidation. The nature of structural alterations by the system that resulted in the inhibition of gelation was not explored in detail. But collagen when digested with collagenase did not gel properly and collagen treated with the MPO system was found to be cleaved on chromatographic analysis. Thus, degradation may be one of the changes in collagen structure caused by the MPO system. The results obtained indicate that MPO/H202/haiide system was able to cause structural alteration of collagen. The degradative effect of the MPO system on collagen structure was discussed as a possible mechanism of tissue damage in inflammatory conditions.