The enzyme from the plants Lathyrus odoratus (sweet pea) and L. sativus (grass pea) also forms 3-(5-oxoisoxazolin-4-yl)-L-alanine in vitro (cf. EC 188.8.131.52). 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 184.108.40.206, cysteine synthase, and EC 220.127.116.11, beta-pyrazolylalanine synthase.