Molecular Modelling of the Interaction of Cyanoacrylate Inhibitors with Photosystem II Part 2. The Effect of Stereochemistry of Inhibitor Binding

The 2-cyanoacrylate inhibitors are a potent class of herbicides which block electron transfer in photosystem II. The spatial arrangement of different functional groups are an important factor in determining activity and a number of derivatives have been used as stereospecific probes of the secondary quinone binding site. More than one region of stereoselectivity in the binding site has been identified which influences the interaction with specific groups of the in­ hibitor. We have studied the interaction of various stereoisomers of the cyanoacrylates with the binding site in the D 1 protein (residues Leu 210 to Val 280) by determining the nonbonded intermolecular energies between the modelled structures calculated by van der Waals and elec­ trostatic interactions after energy minimization of the combined structures to reduce inter and intramolecular strain and have found that the results reflect the experimentally determined data.