Pyridoxal phosphate (PLP,
pyridoxal 5'-
phosphate, P5P), the active form of
vitamin B6, is a
coenzyme in a variety of
enzymatic reactions. The
Enzyme commission has catalogued more than 140 PLP-dependent activities, corresponding to ~4% of all classified activities. The versatility of PLP arises from its ability to covalently bind the substrate, and then to act as an electrophilic catalyst, thereby stabilizing different types of carbanionic reaction intermediates.