title: Chemical and immunological properties of Escherichia coli heat-stable enterotoxin.
abstract: Five heat-stable enterotoxins (STs) produced by enterotoxigenic E. coli (ETEC) strains of porcine, bovine and human origin have been purified to apparent homogeneity. The STs with biological activity in suckling mice and piglets (STA) contained 18 amino acid residues, 10 or 11 different amino acids with a high proportion of acidic amino acids and 6 half-cystines. All 5 purified preparations were heat-stable, not denatured by organic solvents and detergents, resisted protease digestion and treatment at pH 1.0, but were partially inactivated by incubation at pH 12.0 and totally inactivated by reducing and oxidizing agents which disrupted disulfide bonds. The isoelectric point (pI) of the 5 STAs ranged from 3.88 to 4.08. Antiserum raised against strain 431 ST, a porcine class II enteropathogen, neutralized all 5 STAs and was useful as a reagent in a sensitive radioimmunoassay to detect suckling mouse positive strains of ETEC.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D001427:Bacterial Toxins; D004768:Enterotoxins / Q000032:analysis* / Q000276:immunology / Q000302:isolation & purification; D029968:Escherichia coli Proteins
chemical_list: D000596:Amino Acids; D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; C034151:heat stable toxin (E coli)