where is vitamin b6 activated to form its active form pyridoxal phosphate (plp)
Pyridoxal phosphate PLP acts as a coenzyme in all transamination reactions, and in certain decarboxylation, deamination, and racemization reactions of amino acids.[4] The aldehyde group of PLP forms a Schiff-base linkage (internal aldimine) with the ε-amino group of a specific lysine group of the aminotransferase enzyme. The α-amino group of the amino acid substrate displaces the ε-amino group of the active-site lysine residue in a process known as transaldimination. The resulting external aldimine can lose a proton, carbon dioxide, or an amino acid sidechain to become a quinoid intermediate, which in turn can act as a nucleophile in several reaction pathways.