Ball-and-stick model of a pyridoxal phosphate molecule, C₈H₁₂NO₇P, as found in the crystal structure reported in Bull. Chem. Soc. Jpn. (1973) 46, 863–871 and CSD entry PLPHYD10. Pyridoxal phosphate is the active form of vitamin B₆.

This experimentally determined structure differs from the typical idealised textbook representation of the structure of pyridoxal phosphate:

• The acidic phosphate group has donated a proton to the basic pyridine nitrogen atom, resulting in a zwitterion
• The aldehyde group has been hydrated, i.e. it has reacted with a molecule of water to form a geminal diol

Colour code:

  Carbon, C: grey

  Hydrogen, H: white

  Nitrogen, N: blue

  Oxygen, O: red

  Phosphorus, P: orange