Reactive polypeptides. II. Photochemistry of poly(γ‐cinnamyl L‐glutamate)

Poly(γ-cinnamyl L-glutamate) was irradiated in the presence and absence of benzophenone in dichloroethane. The irradiated polymers were analyzed by gas chromatography after hydrolysis. It was possible to assign the transformation in the presence of benzophenone to trans-cis photoisomerization by comparing the effects with those observed for a model compound cinnamyl acetate. The equilibrium composition of cis and trans isomers in the photostationary state was similar for the model compound and the polypeptide. Photoisomerization was found to be accompanied by marked side reactions for the direct irradiation. Circular dichroism spectra were empolyed to study the structure, and no changes in the structure were found for the irradiated polymers.