Open Access5‐ Enol pyruvylshikimate‐3‐phosphate synthase of Klebsiella pneumoniae
Author(s) -
STEINRÜCKEN Hans Christian,
AMRHEIN Nikolaus
Publication year - 1984
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1984.tb08379.x
Subject(s) - chemistry , aminomethylphosphonic acid , biochemistry , glycine , phosphate , enzyme , stereochemistry , metabolite , amino acid
The broad‐spectrum, non‐selective herbicide glyphosate [ N ‐(phosphonomethyl)glycine] is a potent inhibitor of highly purified 5‐ enol pyruvylshikimate‐3‐phosphate (EPSP) synthase (3‐phosphoshikimate 1‐carboxyvinyl‐transferase, EC 2.5.1.19) of Klebsiella pneumoniae. The inhibition is competitive with phospho enol pyruvate (PEP) with K i = 1 μM at pH 6.8 and non‐competetive with shikimate 3‐phosphate, EPSP, and inorganic phosphate. Non‐herbicidal analogues of glyphosate, such as aminomethylphosphonic acid, bis‐ N ‐(phosphonomethyl)glycine and iminodiacetic acid, do not inhibit the enzyme. Inhibition of EPSP synthase by glyphosate strongly increases with increasing pH. Glyphosate protects the enzyme against inactivation by phenylglyoxal, 3‐bromopyruvate, and N ‐ethylmaleimide. It is proposed that glyphosate binds to the PEP‐binding site of EPSP synthase as a transition‐state analogue of PEP. Other PEP‐utilizing enzymes were not found to be subject to inhibition by glyphosate.