Inhibition of kaurene synthetase from castor bean seedling and the germination of tomato, wheat and castor bean seeds by di-ethylene glycol disulfide

Di-ethylene glycol disulfide (ESSE) inhibits the enzyme kaurene synthetase derived from castor bean (Ricinus communis L.) seedlings. The inhibition affects mainly the cyclization of geranylgeranyl pyrophosphate to copalyl pyrophosphate (activity A) and had little or no effect on the further cylization of copalyl pyrophosphate to polycyclic diterpene hydrocarbons (activity B). The inhibition of activity A of kaurene synthetase has a non-competitive reversible pattern (K_i = 10 μM) with regard to geranylgeranyl pyrophosphate. ESSE inhibits the germination of tomato (Solanum lycopersicum L.) wheat (Triticum aestivum) and castor bean (Ricinus communis L.) seeds. The inhibition is reversible and normal germination was restored by washing the seeds with H₂O.GA₃ failed to promote germination of ESSE-treated tomato seeds.