A role of the molecular structure of phytoregulators in chemical signal perception by receptors of plant hormonal systems

Abstract

The role of the molecular structure of phytoregulators in chemical signal perception by receptors of plant hormonal systems and the character of complementarity of a phytoregulator to a receptor have been considered on the basis of (1) the mechanism of signal perception and transduction in a plant cell and (2) the postulates of the physiological paradigm, which lies at the heart of the strategy of chemical design of phytoregulators with specified properties. For regulatory interaction, as distinct from interactions of enzymes with their substrates, topochemical, rather than geometric (a key in a lock), complementarity of a bioregulator to a biotarget is of crucial importance. The action of a bioregulator on a receptor is assumed to be cooperative and quantized. It is shown that molecular parameters of quaternary ammonium salts that determine their antigibberellin (retardant) activity can be used as a measure of topochemical complementarity to a receptor if physiological activities are compared for compounds of the same series (cluster). Submolecular consideration of the physiological activity of a molecule as the sum of the activities of its constituting effector moieties, with taking into account the effect of the moieties that determine polar and hydrophobic binding to a receptor, is suggested as a possible means for developing the QSAR method to make it heuristic.