The enzyme from the plants Lathyrusodoratus (sweet pea) and L. sativus (grass pea) also forms 3-(5-oxoisoxazolin-4-yl)-L-alanine in vitro (cf. EC 184.108.40.206). However, only 3-(5-oxoisoxazolin-2-yl)-L-alanine is formed in vivo. 3-(5-oxoisoxazolin-2-yl)-L-alanine is the biosynthetic precursor of the neurotoxin N3-oxalyl-L-2,3-diaminopropanoic acid, the cause of lathyrism. Closely related and possibly identical to EC 220.127.116.11, cysteine synthase, and EC 18.104.22.168, β-pyrazolylalanine synthase.
Ikegami, F., Kamiya, M., Kuo, Y.H., Lambein, F. and Murakoshi, I. Enzymatic synthesis of two isoxazolylalanine isomers by cysteine synthases in Lathyrus species. Biol. Pharm. Bull.19 (1996) 1214–1215. [PMID: 8889043]