Elastic and quasi-elastic laser light scattering of photochromic macromolecules

The transduction processes of biological photoreceptors appear to involve light-induced conformational transitions of membrane-bound proteins. In order to elucidate various physicochemical pathways by which these processes can be triggered, model studies were undertaken employing photochromic moieties bound to synthetic macromolecules with a labile fold structure. Attention was focused on three aqueous systems: (1) the anionic dis-azo stilbene dye chrysophenine (CHP) and poly(methacrylic acid) (PMA), (2) the cationic dye p-phenyl-azophenyl trimethyl ammonium iodide (PTA) and PMA, and (3) the neutral dye p-phenyl azomethacrylanilid (PM) copolymerized with methacrylic acid (MA). The experimental techniques applied to the model studies included elastic and quasi-elastic laser light scattering, viscosity, and spectrophotometric methods.