Temperature Effects on Botulinum A Toxin. ∗

Abstract

Summary

1) Thermal inactivation of botulinum A toxin was studied. The LD₅₀ was found for samples heated for various times at 40°, 50° and 60° by assaying samples in goldfish. Inactivation curves were plotted by plotting the difference between the LD₅₀ at zero time, and the LD₅₀ at time of treatment, t, against time of heating. At 40°, no inactivation occurred after heating one hour. At 50° and 60°, the inactivation curves were characteristic of a system which contained a minimum of 2 components which inactivated at different rates. Hemagglutinin was not one of these components and gelatin in the buffer did not affect the shape of the inactivation curve. 2) Sedimentation diagrams taken before and after heating at inactivation temperatures suggested that the toxin might be dissociating to form 2 particles having different properties. The data can be explained on the basis of this hypothesis.