Sunlight-induced Conformational Transitions in Spiropyran-containing Polypeptides

Sunlight-induced Conformational Transitions in Spiropyran-containing Polypeptides 13.2.2.1 Spiropyran-modified Poly(L-glutamate)s 

2) exposed to sunlight dashed lines intermediate spectra during decay in the dark. 

On the basis of fluorescence measurements, the driving force responsible for the photoinduced conformational change was attributed to interactions between the photochromic side chains, which differ depending on whether they are in the zwit-terionic merocyanine form or the apolar spiro form. In the dark, the merocyanine units have a strong tendency to give dimeric species as a result the macromolecules are forced to adopt a disordered structure. When the side chains are photoisome-rized to the spiro form, such dimers are destroyed, and the macromolecules assume the helical structure.1631 

2 Photoresponsiveness of Poly(spiropyran-L-glutamate) under Acidic Conditions 

Quite interesting photoresponsive behavior was observed when spiropyran-modified poly(L-glutamate) was dissolved in HFP and a small amount of trifluoroacetic acid 

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