Pyridoxal 5'-phosphate (PLP)

Pyridoxal 5'-phosphate (PLP) is the biologically active coenzyme form of vitamin B6. It is required as a cofactor for more than 100 enzymes, primarily those catalyzing reactions involving amino acids—such as transamination, decarboxylation, and deamination—as well as in neurotransmitter, heme, fatty acid, and hormone biosynthesis. PLP functions by forming a Schiff base with amino groups on enzyme active sites and substrates, stabilizing carbanionic intermediates and promoting diverse group-transfer reactions. Deficiency in PLP results in broad metabolic dysfunctions, and its measurement is a key marker of vitamin B6 status in patients[1][4][6][9].

Other names

PLPPyridoxal phosphatePyridoxal-5-phosphateVitamin B6 phosphatePyridoxal phosphate monohydrate

Acts as a cofactor required for enzyme catalytic activity: forms Schiff base with substrate amino groups, stabilizes intermediates (“electron sink”), facilitates group transfer and rearrangement reactions For related therapies (e.g., pyridoxine supplementation): replenishes PLP pool in deficiency