COOPERATIVE PHENOMENA IN THE PHOTOCYCLE OF D96N MUTANT BACTERIORHODOPSIN

The M intermediate decay in the photocycle of D96N mutant bacteriorhod opsin does not depend on the light intensity of the exciting flash. Co operative phenomena in the photocycle are revealed after addition of a zide causing acceleration of the M decay and making it kinetically wel l separated from the N decay. Increase in the tight intensity induces slight deceleration of the M decay and significant acceleration of the N decay. The data obtained directly confirm our recent model [Komrako v and Kaulen (1995) Biophys, Chem, 56, 113-119], according to which ap pearance of the M(slow) intermediate in the photocycle of the wild typ e bR at high tight intensity is due to destabilization of the N interm ediate leading to the acceleration of the N-->M and N-->bR reactions.