text: Pipecolic acid (piperidine-2-carboxylic acid) is an organic compound with the formula HNCHCOH. It is a carboxylic acid derivative of piperidine and, as such, an amino acid, although not one encoded genetically. Like many other α-amino acids, pipecolic acid is chiral, although the S-stereoisomer is more common. It is a colorless solid.
  Its biosynthesis starts from lysine. CRYM, a taxon-specific  protein that also binds thyroid hormones, is involved in the pipecolic acid pathway.