Amino Acid Analysis and Molecular Weight Determination of Tetanus Toxin

Abstract

A procedure for the isolation of tetanus toxin was developed. The toxin was precipitated with ammonium sulfate and further purified by use of molecular sieve chromatography and preparative disc gel electrophoresis. The degree of purification resulting from these fractionation procedures was monitored by analytical poly-acrylamide gel electrophoresis, immunodiffusion, and immunoelectrophoresis, all three of which demonstrated a single component. There was a 50-fold increase in specific activity between the crude culture filtrate and the final purified product, which had an average specific activity of 300 × 10 6 mouse minimal lethal doses per mg of N. A molecular weight of 140,000 was estimated by gel filtration on Bio-Gel P-200. A complete amino acid analysis of tetanus toxin is presented.