verotoxin ( vt ) , which is immunologically unrelated to vt1 ( shiga-like toxin i ) , was purified from the culture filtrate of escherichia coli hemorrhagic colitis serogroup o157 : h7 strain 3657 by copper ion chelate affinity chromatography followed by anion-exchange chromatography .
C0022023
ion
C0003075
anion