[Thermostable Yersinia pseudotuberculosis toxin: its isolation, purification and the characteristics of its...

Heat-stable toxin, lethal for mice when administered parenterally (LD50 was equal to 4.5 micrograms/mouse), was isolated from Y. pseudotuberculosis grown at a temperature of 8-10 degrees C. The toxin was found to be species-specific protein with a molecular weight of 45 kD, resistant to the action of elevated temperature (boiling for 5 minutes), 0.1-1.0% anionic detergent (sodium dodecyl sulfate) and stable at the pH range between 6.0-8.0. The amino acid sequence of the N-end fragment of the toxin was determined: H2N-Ala-Glu-Val-Asp-Ser-Ser-Glu-Phen-Pro. The toxin was inactivated after treatment with trypsin, chemotrypsin, papain. Antibodies to this toxin were detected in the blood sera of pseudotuberculosis patients.