CO2 switchable response of protein microtubules behaviour and mechanism

Recently, we proposed a small molecular inducing ligand strategy to assemble proteins into highlyordered structures via dual non covalent interactions, i.e. carbohydrate protein interaction and dimerization of Rhodamine B. Using this approach, artificial protein microtubules were successfully constructed. In this study, we find that these microtubules exhibit a perfect CO2 responsiveness; assembly and disassembly of these microtubules were nicely controlled by the alternative passage of CO2 and N2. Upon the injection of CO2, a negative net charged SBA turns into a neutral or positive net charged SBA, which elongated, to some extent, the effective distance between SBA and Rhodamine B, resulting in the disassociation of the Rhodamine B dimer. Further experimental and simulation results reveal that the CO2 responsive mechanism differs from that of solubility change of the previously reported CO2 responsive synthetic material