title: Improved method for purification of human Escherichia coli heat-stable enterotoxin by hydrophobic interaction, molecular-sieve and high performance ion exchange chromatography.
abstract: A heat-stable enterotoxin produced by human enterotoxigenic Escherichia coli has been purified to homogeneity by hydrophobic interaction, molecular-sieve and high performance liquid chromatography with a recovery of 48%. The toxin is composed of 10 different amino acids with a total of 18 amino acid residues, one-third of which are half-cystine. Purified enterotoxin contains no carbohydrate and is biologically active in the suckling mouse test in 2.1-ng quantities. The molecule was heat-stable (80 degrees C, 20 min.) at pH 7 and pH 2 but lost biological activity at pH 12. Biological activity was lost when treated with the reducing agent dithiothreitol, suggesting that the presence of disulfide bridges is required for biological activity.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D001427:Bacterial Toxins / Q000302:isolation & purification*; D055598:Chemical Phenomena; D002621:Chemistry; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002852:Chromatography, Ion Exchange / Q000379:methods; D004768:Enterotoxins / Q000302:isolation & purification*; D004926:Escherichia coli / Q000254:growth & development; D029968:Escherichia coli Proteins
chemical_list: D000596:Amino Acids; D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; C034151:heat stable toxin (E coli)