LIGHT-INDUCED CONFORMATIONAL CHANGES OF POLYPEPTIDES.

The azoaromatic residues attached to macromolecules can be used to control polymer conformation by light. In previous studies, the authors have already shown the occurrence of light-induced conformational changes of polypeptides on some copolymers of beta -p-(phenylazo) benzyl-L-aspartate with beta -benzyl-L-aspartate or gamma -benzyl-L-glutamate. This paper presents results of the investigation performed on a new copolymer series (eA series) of beta -p-(phenylazo)phenethyl-L-aspartate (e) and B-benzyl-L-aspartate (A). Copolymers of eA series were prepared by using varying ratios of beta -benzyl-L-aspartate NCA and beta -p-(phenylazo)phenethyl-L-aspartate NCA. Photoirradiation was carried out using a Corning 7-37 filter. CD spectra were recorded on a JASCO J-20 circular dichrograph apparatus. Molar ellipticities were calculated for the supposedly intrinsic band around 222 nm using the molar concentration of amide groups, while the molar concentration of the azo groups was used for the calculation of the ellipticities associated with the extrinsic bands. Experimental data are presented graphically.