PART 2: CONVERSION OF THE ACTIVE DOMAIN OF NATURAL OPOSSUM LETHAL TOXIN NEUTRALIZING FACTOR TO A SYNTHETIC PEPTIDE, LT-10

Abstract

Lethal toxin neutralizing factor (LTNF), which was isolated from opossum serum, has a molecular weight of 63 kDa and is a potent antidote for toxins from animal, plant, and bacteria. This review describes studies leading to the identification of a small fragment of LTNF, which elicited anti-lethal activity against animal, plant, and bacterial toxins similar to intact natural LTNF. Identification of an active fragment small enough to make a synthetic version of this amazing molecule was viewed as a key step in the process of developing an effective agent for anti-venom and anti-toxin therapy. Purified LTNF was treated with trypsin to cause fragmentation at the arginine and lysine sites. The fragments were separated by high-pressure liquid chromatography (HPLC) and were tested for ability to bind to anti-LTNF and inhibit anti-LTNF binding in an enzyme-linked immunosorbent assay (ELISA). The fragment showing the most binding to anti-LTNF was sequenced. Synthetic peptides consisting of 15 and 10 amino acids from the N-terminal were constructed and designated as LT-15, having amino acid sequence, Leu-Lys-Ala-Met-Asp-Pro-Thr-Pro-Pro-Leu-Trp-Ile-Lys-Thr-Glu and LT-10 having sequence Leu-Lys-Ala-Met-Asp-Pro-Thr-Pro-Pro-Leu. Death of mice due to intra-muscular injection of predetermined lethal doses of toxins derived from animal, plant, and bacterial sources was prevented by treatment with synthetic peptides LT-15 and LT-10. The lethality was inhibited when the treatment was given before or after toxin injection. LT-10 can be made in abundance by chemical synthesis and has the potential to become a universal therapy against intoxication caused by animal, plant, and bacterial toxins.

Keywords: :

• lethal toxin neutralizing factor
• active fragment
• synthetic
• ELISA
• toxin antidote