The direct synthesis of phosphoenolpyruvate from pyruvate byEscherichia coli

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Abstract
Extracts ofEscherichia coliare shown to contain an enzyme system which in the presence of Mg2+catalyses the direct formation of phosphoenolpyruvate from pyruvate andATPwith concomitant formation ofAMPand inorganic phosphate. This enzyme, which has been designated 'phosphoenolpyruvate synthase' (PEP-synthase) has been purified 80-fold and is free of pyruvate kinase activity;PEPsynthesis proceeded most rapidly at pH 8 to 8.5. At pH values between 6.2 and 7.5 the enzyme can catalyse the formation ofATPand pyruvate fromPEP,AMPand inorganic phosphate; if arsenate is used instead of phosphate, pyruvate andADPare produced instead. Studies of the enzymic formation ofPEPwithATPspecifically labelled with32P, and of the reverse reaction with [U-14C]AMP, suggest that thePEP-synthase reaction involves the transfer of a pyrophosphoryl-group. The physiological role ofPEP-synthase has been demonstrated with mutants of E.colidevoid of the enzyme: in contrast to wild-type organisms, such mutants neither grow on pyruvate, lactate or alanine, nor form glycogen from lactate. It is thus concluded thatPEP-synthase plays an important role in the anaplerotic and the biosynthetic reactions which enable the organisms to grow on pyruvate as sole carbon source.

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