Affinity purification of Shiga-like toxin I and Shiga-like toxin II

A facile method is described for affinity purifying Shiga-like toxin I (verotoxin 1) or Shiga-like toxin II (verotoxin 2) from cell-free Escherichia coli culture supernatant solutions using immobilized synthetic analogs of the digalactoside [alpha Gal(1,4)beta Gal] host cell receptor for these toxins. Shiga-like toxin recovery from the crude supernatant solutions ranged from 40 to 60% in thirteen separate trials. Yields ranged from 2 to 3 mg of Shiga-like toxin per liter of culture. Toxin purities were as high as 95%, based on densitometry analysis of preparations analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A major contaminant of these preparations, endotoxin, was readily removed by passing the purified toxins over a polymyxin-agarose affinity column. The digalactoside affinity matrix used in the purification of these toxins could be readily prepared for reuse. (C) 1998 Elsevier Science B.V.