Chemical Properties
Pyridoxal Phosphate Hydrate occurs as a pale yellow-white to light yellow crystalline powder.
It is slightly soluble in water, and practically insoluble in ethanol (99.5).
It dissolves in dilute hydrochloric acid and in sodium hydroxide TS.
The pH of a solution prepared by dissolving 0.1 g of Pyridoxal Phosphate Hydrate in 200 mL of water is between 3.0 and 3.5.
Pyridoxal Phosphate Hydrate is colored to light red by light.
Uses
Pyridoxal 5-phosphate (PLP) (active form of Vitamin B6) is an enzyme prosthetic group that acts as a coenzyme in transamination, decarboxylation and deamination reactions such as the conversion of dopa into dopamine; of glutamate into GABA; of histidine to histamine. PLP works mechanistically through formation of a Schiff-base.
Definition
ChEBI: Pyridoxal 5-phosphate monohydrate is a pyridinecarbaldehyde.
Application
Pyridoxal 5′-phosphate (PLP), an active form of vitamin B6/ pyridoxine is the coenzyme of amino acid metabolism.
Pyridoxal 5′-phosphate monohydrate has been used:
as a component in the reaction mixture for ornithine decarboxylase (ODC) activity assay
as a standard to quantify the concentration of pyridoxal 5′-phosphate (PLP) in cerebrospinal fluid (CSF) of children
as a dietary supplement to study its effects on the lethal phenotype of mutant flies.
Biosynthesis
Two distinct pathways for Pyridoxal 5′-phosphate (PLP) biosynthesis are known.
1.The 'DXP dependent' pathway is found in Escherichia coli and a few members of the γ subdivision of proteobacteria and has been extensively characterized. In this pathway deoxyxylulose 5-phosphate (DXP) is condensed with 3-hydroxy-1-aminoacetone phosphate to give PNP. PNP is oxidized to PLP by PdxH. The DXP dependent pathway is not widely distributed and is surprisingly complex requiring seven enzymes (GapB, PdxB, PdxF (SerC), PdxA, DXS, PdxJ and PdxH). This pathway was the first discovered and it has been extensively reviewed.
2. The second pathway uses Pdx1 and Pdx2 to catalyze the condensation of d-ribose 5-phosphate (R5P), glutamine and glyceraldehyde 3-phosphate to form PLP. The mechanistic and structural characterization of both pathways is at an advanced stage.
General Description
Pyridoxal 5'-phosphate (PLP, vitamin B6) is an essential cofactor in all living systems. It is one of the most versatile cofactors and participates in transamination, decarboxylation, racemization, Cα-Cβ cleavage and α-β elimination reactions. PLP plays an important role in amino acid and carbohydrate metabolism and has been implicated in singlet oxygen resistance. PLP can be used as a dietary supplement in cases of vitamin B6 deficiency. Reduced levels of PLP in the brain can cause neurological dysfunction. By inhibiting AGE formation and working as a coenzyme in chemical reactions, pyridoxal 5’-phosphate can support healthy nerve, eye, cardiovascular and kidney function.
Biological Activity
Pyridoxine participates in the production of lipid and neurotransmitters. Pyridoxal 5′-phosphate (PLP) serves as a cofactor to stabilize carbanions at Cα of amino acids. Pyridoxine deficiency results in peripheral neuropathy. Absence of PLP leads to neonatal epileptic encephalopathy. PLP acts as a coenzyme in transamination, decarboxylation and deamination reactions such as the conversion of dopa into dopamine; of glutamate into γ aminobutyric acid (GABA); of histidine to histamine. PLP works mechanistically through formation of a Schiff-base.
