Abstract
Shiga toxin was purified from the culture supernatant of Shigella dysenteriae 1 by ammonium sulfate fractionation, DEAE-cellulose column chromatography and repeated chromatofocusing column chromatography. About 1.6mg of purified Shiga toxin was obtained from 15 liters of culture with a yield of about 27%. The molecular weight of purified Shiga toxin was estimated to be 62, 000. The toxin consisted of A and B subunits with molecular weights of about 30, 000 and 5, 000-6, 000, respectively. The isoelectric point of purified Shiga toxin was 7.0. Purified Shiga toxin showed the following biological activities: lethal toxicity to mice when injected intraperitoneally with an LD50 of 28ng per mouse; cytotoxicity to Vero cells, killing about 50% of the cells at 1pg and all of the cells at 10pg; and fluid accumulation in rabbit ileal loops at a concentration of more than 1μg.
