The electron microscopic immunolocalization of a copper-zinc superoxide dismutase in association with collagen fibers of periodontal soft tissues.

Periodontal soft tissues were cleaved from freshly extracted human teeth. Tissues were then prepared for subsequent biochemical and morphological studies according to the following plan: 1) immediate immersion in liquid nitrogen for the biochemical assay of superoxide dismutase (SOD); 2) immediate fixation prior to routine preparation for routine transmission electron microscopy; 3) immediate fixation prior to preparation for electron microscopic immunohistochemistry. Biochemical analysis showed that the human periodontal ligament contained about twice as much SOD activity as human skin (dermis), but considerably less enzyme activity than that seen in red blood cells. Interestingly, periodontal SOD activity appeared to decrease with age. Immunohistochemistry localized enzyme activity to the periphery of matrix collagen fibrils and to the glycocalyx of tissue fibroblasts. The pathophysiology of this enzyme regarding inflammatory diseases such as periodontitis is discussed.