Action of Ultra-violet Light on Soluble Collagens

IT has been shown1 that rat tail tendon becomes less soluble after exposure to short wave ultra-violet light and that the amount of soluble collagen in mouse skin was decreased after irradiation2. Fujimori3, working with acetic acid solutions of calf skin collagen, recently showed that irradiation resulted in the acquirement of ability to fluoresce in long wave ultra-violet light. These changes in properties have been ascribed to the formation of cross-links from the aromatic side-chains of phenyl-alanine and tyrosine3,4. Working with suspensions of acid-soluble and neutral salt-soluble collagens from rat skin we have also found that short wave ultra-violet light does produce fluorescence, and we have sought to measure the fluorescence quantitatively and correlate this with changes of solubility and shrinkage temperature after different periods of irradiation.