Pyridoxal phosphate-dependent enzymes mechanism-based inactivation

The pyridoxal phosphate-dependent enzymes have been a major focal point in the development of mechanism-based inactivators. Pyridoxal phosphate (PLP) is utilized in resonance stabilization of carbanions at the a- and /3-carbons of amino acids in a variety of reactions which lead to chemical transformations at the a-, /3-, and y-carbons of the substrate (Walsh, 1979). These carbanion equivalents... 

Because L-vinylglycine also irreversibly inactivates ACC synthase in a time-dependent manner when the enzyme is incubated with L-vinylglycine and pyridoxal phosphate in the absence of AdoMet and because ACC synthase, like other pyridoxal-dependent enzymes, may catalyse p.-y-elimination of AdoMet to produce L-vinylglycine, it has been proposed that the mechanism-based inactivation proceeds through the formation of a vinylglycine-enzyme complex which is inactive (Fig. 3). Detailed kinetic studies indicate that the... 

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