Amino Acid Pathways Absent in Mammals Offer Targets for Safe Herbicides

Amino Acid Pathways Absent in Mammals Offer Targets for Safe Herbicides 

In recent years, agribusiness firms have developed pf empirically several compounds that inhibit essential steps in the biosynthesis of amino acids found in plants but missing in animals. One of these compounds, glyphosate, is a highly specific inhibitor of 5-enol pyruvyl-shikimate-3-phosphate synthase (an enzyme needed for aromatic amino acid biosynthesis). Glyphosate is the active ingredient in the widely used herbicide Roundup. 

Three other classes of compounds, although quite different from each other, are all inhibitors of acetohydroxy acid synthase (an enzyme required for branched-chain amino acid biosynthesis (see fig. 21.10). These three classes are sulfonylureas, imidazolinones, and triazolpyrimidines, which are the active ingredients in, respectively, Oust, Sceptor, and a third commercial herbicide still under development (fig. 21.11). 

Because animals do not synthesize either the aromatic or branched-chain amino acids, these materials can be applied to kill unwanted vegetation without causing harm to domestic animals or humans. Certain derivatives can often be selectively applied to combat noxious plants without appreciable harm to crops. More promising, however, is the prospect of using biotechnology to incorporate genes for enzymes specifically resistant to one of the herbicides into seeds used for crop production. 

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Amino Acid Pathways Absent in Mammals Offer Targets for Safe Herbicides Chorismate Is a Common Precursor of the Aromatic Amino Acid Family... 

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