Photoinduced Structural and Functional Changes of an Azobenzene Containing Amphiphilic Sequential Polypeptide

Signal-Triggered Transmembrane Ion Transport through Synthetic Channels

“…Dimers of gramicidin [19] and of a glutamic acid based peptide [20] have been linked with azobenzene to produce systems that show photomodulated ion transport. Woolley modified gramicidin with azobenzene endgroups to block the pore after isomerization to the cis-form [9].…”

Azobenzene Polymers for Photonic Applications

“…In an amphiphilic polypeptide system, selfassembled micelles were formed in the dark and could be disaggregated with light (Higuchi et al, 1994). When allowed to assemble as a transmembrane structure, the aggregate could be reversibly formed and destroyed using light, which allowed for reversible photoswitching of ion transport (Higuchi et al, 1995a). Related experiments on methacrylates (Chen et al, 1997a;Angiolini et al, 1995) and polypeptides (Sisido et al, 1991b) showed that a polymer's chiral helix could be reversibly suppressed on irradiation.…”

Photoswitchable Polypeptides

“…[117±121] The polypeptide XXI was first placed at a water/air interface and a monolayer formed; then NaOH was injected into the water phase beneath the solid condensed monolayer. [120] Fluorescence and microscopic measurements provided evidence that the polypeptide was able to form bundles of helical molecules analogous to their natural counterparts, which acted as transmembrane channels for K + ions. [117±121] The compound XXIII, consisting of two amphiphilic helical rods linked by an azobenzene moiety, was found to form micelles and ordered aggregates in aqueous solution in the dark, when the azo moiety is in the trans configuration.…”

“…This resulted in selective saponification of the ester methyl groups on the water side of the monolayer only, so that the final polypeptide XXIII consisted of helical rods with COOH side chains on one side (hydrophilic face) and COOCH 3 side chains on the other (hydrophobic face) ( Figure 18). [120] The investigation was then extended to a monolayer formed from dipalmitoyl phosphatidyl choline and the same amphiphilic photochromic polypeptide XXIII. Photoisomerization of the azo linkage into the cis configuration, and the consequent bending in the structure of the molecules, induced disaggregation and disruption of the micelles.…”