Pyridoxal phosphate
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.
Etymology
PLP stands for pyridoxal 5' phosphate and PMP stands for pyridoxamine 5' phosphate. Consequently, the L in PLP does not indicate a levorotatory chiral center.
The common names pyridoxamine (aminomethyl group at position 4), pyroxidal (carbaldehyde group) and pyridoxine (alkaloid, has hydroxymethyl) derive from pyridine + oxy + a IUPAC suffix.Pyridine, in turn, comes from the Greek πῦρ, πυρός (pyr, fire) + -ide + -ine.
It should be noted that the oxy infix in pyridoxine is not based on Hantzsch–Widman nomenclature (the heterocyclic ring is simply a modified pyridine) and the pyr- root does not indicate it to be a dimeric acid anhydride (unlike pyrophosphate).