The photochemical conversion in the chemically modified bacteriorhodopsin using polyvinyl alcohol as the protectant

In recent years, it has been shown that chemically modified bacteriorhodopsin (BR) containing large organic cations has a long lifetime of the O state. So it can be used to study the photochemical conversion between the O state and the P state. Chemically modified BR was obtained by adding cations to the deionized blue membrane (dIbR). However, BR molecules were easy to aggregate because the large organic cations were bound to dIbR. In this paper, a water-soluble polymer, polyvinyl alcohol (PVA), was used as a protectant and added to dIbR before the addition of large organic cations. It can prevent the aggregation of the molecules of chemically modified BR. The surface binding of PVA not only affected the stability properties but also played a very important role in controlling the photochemical properties of chemically modified BR.