Polarographic Investigation Op B-N-Oxalyl-L-A,B-Diaminofr.Ofrionic Acid, A Neurotoxin Prom The Seeds Op Lathyrus Sativus(Guaya)

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Addis Ababa Universty


Polarographic investigations of £-N-Oxalyl-L-a > 0-Diaminopropionic acid, ODAP, a neurotoxin from the seeds of Lathyrus sativus(Guaya) have been made. Aqueous solutions of ODAP in KC1 supporting electrolyte gave a single polarographic wave with a half-wave potential of -1 ,518V, This wave was found to be due to the irreversible discharge of hydrogen. The reduction wave disappeared on standing and may be due to intramolecular rearrangement leading to lactone formation. At more positive potential a second peak appears for pH’s less than 2. The reduction wave shifts towards more positive values as the pH decreases. This reduction wave could be due to a direct reduction of the protonated amino acid, Polarograms of qqueous solution of Cu(ll), Ni(ll ), Zn(ll), Cd(ll), Pb(ll) and Co(ll) in KC1 supporting electrolyte were not affected by the addition of ODAP, However, in ammonia buffer ( pH = 8,2) and when ODAP was added only Ni(ll) and Co(ll) showed larger shifts in the differential pulse polarographic peak potentials after one day, Polarographic behavior of complexes of ODAP with Ni(ll) and Co(ll) in borax buffer (pH = 9.2) have been studied. The reduction of both complexes were polarographically irreversible. The stability constant and ligand number of the Ni(ll)~ ODAP complex in borax ( pH = 9 ,2) were determined. The simple and complex metal ions were reduced irreversibly. The ligand number was determined to be 2 and the stability constant calculated to be log $= 7.4



B-N-Oxalyl-L-A,B-Diaminofr.Ofrionic Acid