“…Stability of a preparation of SEA labeled with 125I at 37 MCi of protein per Mg (A) and 3 MCi of protein per Mg (0). Reaction time was 2 min, and storage temperature was -23 C. 4 tCi/,ug of protein), although initially similar in amount to that of toxins with high specific activity, does not increase in amount on storage for as long as 60 days at -23 C. Aggregates were not found in untreated enterotoxins, so their presence in radiolabeled enterotoxins resulted from the labeling procedure (data not shown). Table 2 contains data on the immunoreactivity of the monomeric and aggregate fractions of high-specific-activity 125I-labeled enterotoxins.…”