Sulfometuron methyl inhibition

There are several commercially available sulfonylurea herbicides that contain a 2-pyrimidine group <2006H(68)561>. These compounds, which function by inhibition of acetolactate synthase (ALS), an enzyme involved in the early stage of branched-chain amino acid synthesis, include sulfometuron-methyl 1095, primisulfuron-methyl 1096, chlorimuron-ethyl 1097, bensulfuron-methyl 1098, ethoxysulfuron 1099, nicosulfuron 1100, and pyrazosulfuron-ethyl 1101. Related nonsulfonylureas include the sulfide pyrftalid 1102 and the ether pyriminobac-methyl 1103. 

S5mthase is not present in mammals it is a popular target for herbicides. It is inhibited by many of the most widely used herbicides including sulfometuron methyl, whose structure is shown here. 

Other classes of herbicides in addition to the imidazolinones kill plants by inhibiting AHAS e.g., the sulfonylureas (9,10). To characterize the level and spectrum of resistance for the three resistant corn lines, plants were treated with two imidazolinones, imazethapyr and imazaquin, and with the sulfonylurea sulfometuron methyl. 

Table II. Reversal and Potentiation of Inhibition Sulfometuron Methyl Growth ...

Sulfometuron methyl, the active ingredient of Oust, is a sulfonylurea that inhibits the synthesis of the essential amino acids valine, leucine, and isoleucine. 

The inhibition by the sulfonylurea herbicide sulfometuron-methyl (SMM, Oust Figure 2.4) has been well characterized. The inhibition is complex and shows rapid and slow phases. Reaction progress curves are biphasic in the presence of the inhibitor both stages are inhibited reversibly and competitively with respect to pyruvate. With ALS II from... 

---