Direct computer simulation of ferredoxin and FNR complex formation in solution.

Ferredoxin reduced by Photosystem I in light serves as an electron donor for the reduction of NADP(+) to NADPH, and this reaction is catalyzed by enzyme ferredoxin:NADP(+)-reductase (FNR). Kinetics and mechanisms of this reaction have been extensively studied experimentally by site-specific mutagenesis, laser flash photolysis and stopped-flow methods. We have applied a method of multiparticle computer simulation to study the effects of electrostatic interactions upon the reaction rate of Fd-FNR complex formation. Using the model we calculated rate constants of Fd-FNR complex formation for the wild-type proteins and some mutant forms of FNR at different values of ionic strength. Simulation revealed that electrostatic interactions play an important role in Fd-FNR complex formation and define its specificity.