Studies on protein denaturation and enzyme inactivation caused by lipid hydroperoxides containing radicals

It has been shown directly by means of the HPLC system that reactive lipid hydroperoxides containing the corresponding radicals, which are produced by autoxidative chain reactions from polyunsaturated fatty acids under atmospheric conditions, can decompose proteins into their fragments or fission products according to fragility originated in their structural characteristics. Similarly, it has been verified that several enzymes are inactivated to different extents by the strong actions of active lipid hydroperoxides. It has also been clarified that the activity of an enzyme (lactate dehydrogenase) is completely destroyed just by a water-soluble radical (vitamin C radical or ovalbumin protein radical), which is prepared by radical migration between lipid radicals and radical scavengers such as vitamin C and ovalbumin by means of constrained direct contact of both compounds. Therefore, it is strongly suggested that lipid hydroperoxides containing radicals may play a significant role with regard to protein metabolism in destroying the structures of proteins and the activities of enzymes.