Pyridoxal phosphate
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| Names | |
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IUPAC name
(4-formyl-5-hydroxy-6-methylpyridin-3-yl)methyl phosphate
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| Other names
Pyridoxal 5-phosphate, PAL-P, PLP, Vitamin B6 phosphate
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| Identifiers | |
54-47-7 
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| 3D model (Jmol) | Interactive image |
| ChEBI | CHEBI:18405 |
| ChEMBL |
ChEMBL82202 
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| ECHA InfoCard | 100.000.190 |
| 5249 | |
| MeSH | Pyridoxal+Phosphate |
| PubChem | 1051 |
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| Properties | |
| C8H10NO6P | |
| Molar mass | 247.142 g/mol |
| Density | 1.638±0.06 g/cm3 |
| Melting point | 139 to 142 °C (282 to 288 °F; 412 to 415 K) |
| Acidity (pKa) | 1.56 |
| Pharmacology | |
| A11HA06 (WHO) | |
| Hazards | |
| Flash point | 296.0±32.9 °C |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 (what is ?) |
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| Infobox references | |
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.
PLP acts as a coenzyme in all transamination reactions, and in certain decarboxylation, deamination, and racemization reactions of amino acids. 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.
In transamination, after deprotonation the quinoid intermediate accepts a proton at a different position to become a ketimine. The resulting ketimine is hydrolysed so that the amino group remains on the complex. In addition, PLP is used by aminotransferases (or transaminases) that act upon unusual sugars such as perosamine and desosamine. In these reactions, the PLP reacts with glutamate, which transfers its alpha-amino group to PLP to make pyridoxamine phosphate (PMP). PMP then transfers its nitrogen to the sugar, making an amino sugar.
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Wikipedia