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 Esc herichia coli culture supernatant solutions using immobilized syntheti c analogs of the digalactoside [alpha Gal(1,4)beta Gal] host cell rece ptor for these toxins. Shiga-like toxin recovery from the crude supern atant solutions ranged from 40 to 60% in thirteen separate trials. Yie lds ranged from 2 to 3 mg of Shiga-like toxin per liter of culture. To xin purities were as high as 95%, based on densitometry analysis of pr eparations analyzed by sodium dodecyl sulfate-polyacrylamide gel elect rophoresis. A major contaminant of these preparations, endotoxin, was readily removed by passing the purified toxins over a polymyxin-agaros e affinity column. The digalactoside affinity matrix used in the purif ication of these toxins could be readily prepared for reuse. (C) 1998 Elsevier Science B.V.