|
Acetolactate synthase(ALS) is the common enzyme in the biosynthetic of valine, leucine, and isoleucine, and is the target of several classes of structually unrelated herbicides, including sulfonylureas, imidazolinones, and triazolopyrimidines. In an effort to develop new and desirable herbicides, we have synthesized 4,6-dimethoxypyrimidine derivatives, and examined their inhibitory activities on pea ALS. The most active compound was found to be K11570 and IC50 value for K11570 was 0.2 μM. The inhibition of pea ALS by K11570 was biphasic, showing increased inhibition with incubation time. The K11570 showed mixed-type inhibition with respect to substrate pyruvate. Dual inhibition analysis of K11570 versus sulfonylurea herbicide Ally and feedback inhibitor leucine revealed that three inhibitors were competitive for binding to ALS. The arginine modified enzyme showed decreased inhibition by K11570, sulfonylurea Ally, and leucine, in constrast to, tryptophan modification did not affect on the sensitivity of ALS to the inhibitors.
|