Pipecolic acid (piperidine-2-carboxylic acid) is an organic compound with the formula HNC5H9CO2H. 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.[1]CRYM, a taxon-specific protein that also binds thyroid hormones, is involved in the pipecolic acid pathway.
^Gatto, Gregory J.; Boyne, Michael T.; Kelleher, Neil L.; Walsh, Christopher T. (2006). "Biosynthesis of Pipecolic Acid by RapL, a Lysine Cyclodeaminase Encoded in the Rapamycin Gene Cluster". Journal of the American Chemical Society. 128 (11): 3838–3847. doi:10.1021/ja0587603. PMID16536560.
^Plecko B, Hikel C, Korenke GC, et al. (2005). "Pipecolic acid as a diagnostic marker of pyridoxine-dependent epilepsy". Neuropediatrics. 36 (3): 200–5. doi:10.1055/s-2005-865727. PMID15944906.