Preliminary characterization of the heat-labile enterotoxin of Escherichia coli F11(P155).

Abstract

Certain characteristics of the heat-labile enterotoxin produced by Escherichia coli F11 (P155) are reported in this paper. When preparations of toxin were passed through Diaflo membranes, no toxic activity was detected in the ultrafiltrate from XM-50 membranes; however, toxicity was present in both ultrafiltrate and retentate from XM-300 membranes. The passage of toxin through XM-300 membranes was not increased by any of the following agents: various buffer salts, sodium deoxycholate (0.5%), disodium EDTA (7.5 mM), and a mixture of urea (8M) and 2-mercaptoethanol (8 mM). Various preparations of the toxin were fractionated on Sepharose columns; the bulk of the activity was associated with the fractions eluted with the void volume of Sepharose 4B. On Sepharose 2B, the toxin spread over a wide area of the agarose bed, and two peaks of activity were observed. When each toxin peak was passed through Sepharose 2B, toxin activity was not confined to a narrow band of fractions but was present in fractions collected over a wide area of the gel. Peaks in the elution profile, as determined by absorption of UV light, could not be associated with the toxin, since a similar UV pattern was obtained with the isogenic nonenterotoxigenic strain F11.