N-LIKE INTERMEDIATE IN THE PHOTOCYCLE OF THE ACID PURPLE FORM OF BACTERIORHODOPSIN

The photocycle of the acid-purple form of bacteriorhodopsin (BR) was s tudied by multiwavelength absorption kinetic measurements, The data we re evaluated using a new method based on the differences in the kineti cs of the absorption changes at different wavelengths [Tokaji, Zs. (19 95) FEES Lett. 357, 156-160]. The evaluation indicates that, in contra st to the previous suggestion, the photocycle of the acid purple BR co ntains an intermediate that, in its spectral and kinetic properties, r esembles the N intermediate of the alkaline BR photocycle. (C) 1997 Fe deration of European Biochemical Societies.