Transmission Changes in Ultraviolet Glasses during High Temperature Exposure to Light.

Condensation of this thiohydantoin derivative with benzaldehyde and subsequent treatment with alkali yields benzal thiohydantoin (D), and the formation of this product demonstrates5 the presence in the original peptide of a glycine group with free carboxyl. Other considerations, not yet ripe for discussion here, suggest that a free carboxyl group belonging to eysteine is not also present. The formation of two thiohydantoin rings in the first condensation product (C) would also confirm the existence of a free a-carboxyl group in the glutamic acid residue of glutathione. It is interesting to note that structures A and B, with a slight preference for B, were chosen by Pirie and Pinhey6 on the basis of dissociation constants deduced from results obtained in the titration of glutathione.