STUDIES ON IMMUNITY TO TOXINS OFCLOSTRIDIUM BOTULINUMI. A

Abstract

A simplified procedure for purification of C. botulinum type A toxin was described. Toxin was precipitated from the culture by acidification at pH 3.5, and the precipitate was washed with water at pH 5. Toxin was extracted from the washed precipitate with 0 075 [image] CaCl2 and precipitated from the extract at pH 3.7. The toxin was dissolved in phosphate buffer at pH 6.8 and precipitated with 15% ethanol in the cold. This fraction was essentially pure toxin and could be crystallized by precipitation with arnmonium sulfate. The crystalline toxin had a specific activity of 269 x 106 mouse intraperitoneal LDso/mg N and was essentially homogeneous when examined in the analytical ultracentrifuge. The fractionation procedures were repro ducible and could be applied on a scale suitable for routine isolation of toxin for conversion to toxoid.