Detection and purification of the free A subunit of heat-labile enterotoxin produced by enterotoxigenic Escherichia coli |
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Authors: | Takao Tsuji Takeshi Honda Toshio Miwatani Akio Miyama |
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Institution: | Department of Microbiology, Fujita Health University School of Medicine, Toyoake Aichi, Japan. |
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Abstract: | After removal of total B subunit and heat-labile enterotoxin (LT) from crude cell extracts of enterotoxigenic Escherichia coli (HB 101-EWD 299) by Bio-gel A 5 m column chromatography, the crude cell extract was shown to contain a free A subunit (A' subunit) that did not bind to the coligenoid of the B subunits. The A' subunit was found to be immunologically identical to the A subunit of holo-LT and was purified to show only one band in SDS-poly-acrylamide gel electrophoresis (PAGE). The mobility of the A' subunit was identical to that of the A subunit of holo-LT. The pI value of the A' subunit was also the same as that of the A subunit of holo-LT. These data suggest that in enterotoxigenic E. coli there is free A subunit which may be involved in formation of holo-LT, analogously to free B subunit (coligenoid), and that the free A subunit is physicochemically and immunologically identical to the A subunit of holo-LT. |
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Keywords: | Heat-labile enterotoxin Subunits A B Enterotoxigenic Escherichia coli |
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