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Abstract:
The action of ultraviolet light (wavelength 2537Å) on cysteine, cystine, methionine, reduced and oxidized glutathione, and reduced insulin has been studied. Special attention is focussed on the influence of pH and of oxygen tension upon all reactions. On irradiation disulphides in acid medium, reductive cleavage of S-S bonds dominates. This reduction is not greatly influenced by oxygen. On irradiation of thiols in alkaline solution, however, the C-S bond is reductively split if oxygen is excluded. Most of the data obtained are discussed with regard to these two very interesting reactions. On irradiation of methionine, a-aminobutyric acid is the main product when oxygen is excluded. In the presence of oxygen the cleavage of the C-S bondage is inhibited. The thioether is then oxidized.