HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY PURIFICATION AND AMINO-ACID-SEQUENCE OF TOXINS FROM THE MUSCARINIC FRACTION OF TITYUS DISCREPANS SCORPION-VENOM

Tityus discrepans venom was fractionated by gel filtration on Sephadex (R) G-50 column. The peptides in fraction II from Sephadex(R) were fur ther purified by high performance liquid chromatography, through a C4 reverse-phase column. Lethality of purified peptides was determined by injection into mice and crabs, and their effects were verified electr ophysiologically on frog (Hyla crepitans) sartorius neuromuscular junc tion. Toxins having retention times between 39.6 and 40.7 min depolari zed the muscle membrane and caused acetylcholine release at the endpla te. The toxin eluted at 42.67 min increased the frequency of miniature endplate potentials without depolarizing muscle fibres. The four most active toxins were reduced, carboxymethylated and sequenced by automa tic Edman degradation and named TdII-1 to II-4. Toxin gamma from Tityu s serrulatus venom and the toxins from T. discrepans venom were found to be structurally distinct. TdII-1 to II-4 lack the pancreatic effect s of T. serrulatus' toxin gamma; yet, the five toxins act on Na+ chann els.