RING-NITROGEN OF BETA-ISOXAZOLINONE-ALANINE IS INCORPORATED INTO THE NEUROTOXIN, BETA-N-OXALYL-L-ALPHA,BETA-DIAMINOPROPIONIC ACID, IN CALLUS-TISSUE OF LATHYRUS-SATIVUS

The biosynthesis of beta-N-oxalyl-L-alpha,beta-diaminopropionic acid ( ODAP), the neurotoxin of the grass pea, Lathyrus sativus, was studied in habituated call-us tissue derived from L. sativus leaves. Chemicall y synthesized beta-(isoxazolin-5-on-2-yl)-alanine containing the stabl e isotopes N-15 or C-13 in the ring, or N-15 labelled beta-N-hydroxy-L -alpha,beta-diaminopropionic acid (HDAP) was used as precursor. The ni trogen of the isoxazolinone ring is found to be quantitatively incorpo rated into ODAP, while the carbons of the same ring do not become part of the ODAP molecule. Also, the beta-amino group of HDAP becomes inco rporated, suggesting that this compound may be a shortlived intermedia te.