The photocycle of bacteriorhodopsin immobilized in poly(vinyl alcohol) film

The kinetics of photoelectric and optical signals were measured on samples containing oriented purple membranes immobilized in a poly(vinyl alcohol) film and on purple membranes introduced into a PVA—H2O mixture. The bacteriorhodopsin photocycle in the PVA—H2O mixture was complete. The only observed changes were the slowing down of the optical and electrical signals in relation to the M412‐O640 and O640‐bRa11‐trans steps. In the PVA film the O640 intermediate disappeared and a negative photoelectric signal appeared.