Sandbox Reserved 764: Difference between revisions

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==Inhibition==

Glyphosate acts as a competitive inhibitor of PEP and binds more tightly to the EPSP synthase-S3P complex than does PEP. Unlike PEP, glyphosate has no affinity for the enzyme alone. The major difference between glyphosate and PEP is that the dissociation rate for glyphosate is 2,300 times slower than PEP. Therefore, once glyphosate binds the enzyme-substrate complex (EPSP synthase-S3P) the enzyme is inactivated. There are other factors that contribute to glyphosate’s herbicidal activity. The shikimate pathway is normally controlled by a process called feedback inhibition. In the shikimate pathway, arogenate (a product of the pathway) is a potent inhibitor of the first enzyme in the shikimate pathway, 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase (DAHP synthase) (Fig 13). Inhibition of EPSP synthase by glyphosate results in the decreased levels of arogenate causing the deregulation of the shikimate pathway due to increased DAHP synthase activity.

Glyphosate, a systemic herbicide, acts as a competitive inhibitor of PEP and binds more tightly to the EPSP synthase-S3P complex than does PEP <ref>PMID:16663714</ref>. Unlike PEP, glyphosate has no affinity for the enzyme alone. The major difference between glyphosate and PEP is that the dissociation rate for glyphosate is 2,300 times slower than PEP <ref>PMID:16663714</ref>. Therefore, once glyphosate binds the enzyme-substrate complex (EPSP synthase-S3P) the enzyme is inactivated.

[[Image:glyphosate.jpg|frame|left|Figure 3: Comparison of PEP structure to Glyphosate structure]]

Sandbox Reserved 764: Difference between revisions

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 ==Inhibition==
-Glyphosate acts as a competitive inhibitor of PEP and binds more tightly to the EPSP synthase-S3P complex than does PEP. Unlike PEP, glyphosate has no affinity for the enzyme alone. The major difference between glyphosate and PEP is that the dissociation rate for glyphosate is 2,300 times slower than PEP. Therefore, once glyphosate binds the enzyme-substrate complex (EPSP synthase-S3P) the enzyme is  inactivated. There are other factors that contribute to glyphosate’s herbicidal activity. The shikimate pathway is normally controlled by a process called feedback inhibition. In the shikimate pathway, arogenate (a product of the pathway) is a potent inhibitor of the first enzyme in the shikimate pathway, 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase (DAHP synthase) (Fig 13). Inhibition of EPSP synthase by glyphosate results in the decreased levels of arogenate causing the deregulation of the shikimate pathway due to increased DAHP synthase activity.
+Glyphosate, a systemic herbicide, acts as a competitive inhibitor of PEP and binds more tightly to the EPSP synthase-S3P complex than does PEP <ref>PMID:16663714</ref>. Unlike PEP, glyphosate has no affinity for the enzyme alone. The major difference between glyphosate and PEP is that the dissociation rate for glyphosate is 2,300 times slower than PEP <ref>PMID:16663714</ref>. Therefore, once glyphosate binds the enzyme-substrate complex (EPSP synthase-S3P) the enzyme is  inactivated.
 [[Image:glyphosate.jpg|frame|left|Figure 3: Comparison of PEP structure to Glyphosate structure]]