THE MOLECULAR BIOLOGY OF PLAGUE TOXIN

Abstract

This chapter discusses the molecular biology of plague toxin. Studies on the chemical nature and biological action of plague toxin require adequately pure material. The chapter lists some pertinent properties of the best samples that have been subjected to various electrophoretic procedures. The most purified material contained approximately 95% protein and was found to be free of nucleic acids, carbohydrates, lipids and capsular material. It had an intravenous LD50 for 16 gram to 18 gram Swiss albino mice of 0.1 μg of protein and exhibited one band in the sensitive Oudin and Ouchterlony gel diffusion precipitation reactions. To determine whether plague toxin possessed any unusual components that could account for its high toxicity, detailed elemental and amino acid analyses were performed on the most highly purified samples of toxin available. In the study, 18 amino acids and a number of elements were identified. On a dry weight basis, over 98% of the toxin molecule was accounted for by organic analysis including ammonia and ash content. There was nothing unusual about the toxin molecule aside from the high proportion of acidic amino acids, which verified the previously observed isoelectric point of the toxin of 4.7.