Photoinduced conformational transition of polypeptides containing azobenzenesulfonate in the side chains

Permeability Changes of a Porous Membrane by an Adsorbed Photoresponsive Polypeptide

“…The synthesis of azo · S-PGA and pro-azo · S has been described in detail previously. 6 PGA with a small amount of pyrene in the side chains (PGA *) was prepared to determine the amount of adsorption of PGA in the porous membrane by means of fluorescence analysis. PGA * was synthesized by the condensation reaction as follows.…”

“…6 In previous studies, 1 -s we showed that the transport properties of polypeptide charged membranes are controlled by pH-induced con- …”

Photocontrol of the Structure and Functions of a Polypeptide Membrane Composed of Poly(L-glutamic acid) Containing Pararosaniline Leucocyanide Groups in the Side Chains

“…It is clear that the light irradiation produced a strong absorption band centered at 576 nm, which could be correlated with the formation of triarylmethyl cations. We have already shown 15 that the pararosaniline leucohydroxide (rose(OH)) moieties, whose pKa is 8. could be dissociated in acid solution even in the dark due to the neutralization reaction. 16 Their photodissociation could thus be achieved only in a limited pH region above neutrality.…”

“…Figure 2 shows the changes of the CD spectra of the rose(CN)-PGA membrane dipped in aqueous solution on irradiation at pH 5.3. In the dark, a negative band at 222 nm, associated with the ix-helix content, was observed. The helix content was calculated by a similar method 18 15 The light irradiation on the rose-PGA membrane could induce changes in the backbone structure of the polypeptide in the membrane. This behavior can be explained in terms of the cooperative effect between the photodissociation of the pararosaniline leucohydroxide moiety with production of a hydroxide ion and induced acid dissociation of L-glutamic acid moiety accompanied by increase in pH in the membrane phase on the irradiation.…”

“…9 Recently, we also reported the photo-induced conformational changes of poly(L-glutamic acid) containing azobenzenesulfonate 10 and pararosaniline leucohydroxide moieties, 11 respectively, in the side chains. The conformation of the membrane composed of poly(L-glutamic acid) containing pararosaniline leucohydroxide moieties in the side chains was changed by a pH increase resulting from the photoproduction of OH-ions from the leucohydroxide moieties in the membrane phase.…”