Cross-linking of collagen CNBr peptides by ozone or UV light

Insoluble collagen from rat tail tendon was digested with cyanogen bromide. The resultant peptides were dissolved in 0.1% SDS solution and separated by gel filtration and gel electrophoresis. Cross-linking occurred in CNBr-cleaved peptides when they were exposed to ozone or biologically effective UV (300 nm) radiation. The enhancement of a blue fluorescence at 430 nm (excited at 350 nm) was found to be associated with oxidized, cross-linked peptides. Polymeric peptides, formed in collagen with aging, also exhibited enhanced blue fluorescence.