| Abstract: | The mechanism of I700 decay, representing an early event in the phytochrome Pr→ Pfr phototransformation, was reanalyzed in the microsecond range by conventional laser flash photolysis as well as by two-laser/two-color flash photolysis. Three kinetic models that might describe the I700 decay mechanism following Pr excitation were considered: a parallel, a sequential, and an equilibrium model. These models were used to mathematically simulate both the one- and two-laser flash experiments in an effort to select the model best describing the I700 decay. The sequential model could be excluded already on the basis of the one-laser flash photolysis results alone. Discussion of the two-laser/two-color flash rcsults in the context of the equilibrium and the parallel models is presented. |
