Exotoxins of Pseudomonas aeruginosa. II. Concentration, Purification, and Characterization of Exotoxin A

Abstract

Exotoxin A of Pseudomonas aeruginosa (PA-l03) could be concentrated readily by precipitation with zinc acetate and ammonium sulfate. The toxin was purified by column chromatography with use of DEAE-cellulose and Sephadex G-200. The final product contained about 8,000 mouse ld₅₀/mg of protein. The toxin has a sedimentation constant of 3.35 S, and the molecular weight is estimated to be in the range of 50,000. The toxin is readily inactivated by trypsin and by heating at 70 C for 30 min. It can also be inactivated by incubation with sodium deoxycholate but not by similar treatment with sodium glycocholate, sodium cholate, or lauryl sulfate. Efforts to convert this toxin to toxoid so far have been unsuccessful.