This study examined the synthesis of copolymers of an alanine-derived chiral N-propargylamide [N-(tert-butoxycarbonyl)-L-alanine N'-propargylamide] with an azobenzene-containing N-propargylamide [N-4-(phenylazo)benzoyl-L-alanine N'-propargylamide] and the transformation of the higher order structure of the copolymers by photoirradiation. The trans-azobenzene moiety of the copolymers isomerized into the cis one, which was accompanied by the transformation of the helical structure into a random state by UV irradiation. Visible-light irradiation induced the reisomerization of cis-azobenzene into the trans one, but it did not induce the recovery of the higher order structure. (C) 2004 Wiley Periodicals, Inc.