NUTRITIONAL AND TOXICOLOGICAL ASSESSMENT OF AN N-6-DIETHYLPHOSPHOLYSYL PEPTIDE - A SYNTHETIC COMPOUND RESEMBLING THE COVALENTLY BOUND METABOLITE OF AN ORGANOPHOSPHATE PESTICIDE TO PROTEIN-BOUND LYSINE

A 1- and 5-week mouse growth study was conducted to evaluate the poten tial toxicological implications and nutritional value of a phosphoryla ted peptide, Ac-Ala-Lys(PO(3)Et(2))-Val-OEt (a synthetic model resembl ing the covalently attached metabolite of organophosphate pesticide to protein-bound lysine), and the nonphosphorylated peptide Ac-Ala-Lys-V al-OEt. A basal diet, adequate in all nutrients except lysine (0.26%), was supplemented with 1 and 2% of the phosphorylated or the nonphosph orylated peptide, and with the amounts of crystalline lysine equivalen t to those provided by the peptides. Relative lysine bioavailability w as calculated by comparing growth of mice fed a peptide diet with that of mice fed basal plus an equivalent amount of crystalline lysine. Va lues for relative bioavailability of lysine (L-lysine = 100) in the ph osphorylated peptide after 1 or 5 weeks of test mere zero. Values for relative bioavailability of lysine in the nonphosphorylated peptide we re, however, 100 and 86-99% after 1 and 5 weeks of test, respectively. The addition of the peptides had no significant adverse effects on re lative mouse organ weights or most blood hematology parameters.