SUBUNIT STRUCTURE OF CHOLERA TOXIN
SUBUNIT STRUCTURE OF CHOLERA TOXIN
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DOI：
10.1099/00221287-76-2-417
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发表时间：
1973-01-01
期刊：
影响因子：
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通讯作者：
HOLMGREN, J
中科院分区：
文献类型：
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作者：
LONNROTH, I;HOLMGREN, J
十二烷基硫酸钠聚丙烯酰胺凝胶电泳显示霍乱肠外毒素含有两种亚基，分子量分别为28000和8000。在抗原性相同的天然类毒素中，可证明轻（L）组分而非重（H）组分。通过还原和烷基化分离的H组分表明它是二硫键桥接的二聚体。在酸性pH下的凝胶过滤允许分离H和L亚基。与分离的亚基的馏分是无毒的（皮肤试验），在含有两个亚基的中间过滤速率的馏分相反。具有约3.5的L：H比的级分甚至比完整毒素（L：H比约2）更有毒性。将分离的亚基加入到毒性组分中通常会引起抑制作用，只有在例外情况下才能增强毒性。这些数据表明，霍乱毒素可能由7个L亚基和1个H亚基的聚集体组成，而天然类毒素似乎仅由聚集的L链组成。
Two types of subunit, with molecular weights estimated to be 28000 and 8000, were demonstrated in the cholera exo-enterotoxin by sodium dodecylsulphate polyacrylamide electrophoresis. The light (L) component but not the heavy (H) was demonstrable in the antigenically identical natural toxoid. A spilt of the H component by reduction and alkylation suggested it to be a disulphide-bridged dimer.Gel filtration at acid pH permitted separation of the H and L subunits in isolated form. Fractions with isolated subunits were non-toxic (skin test), in contrast to fractions with intermediate filtration rate containing both subunits. Fractions with a L:H ratio of about 3.5 were even more toxic than the intact toxin (L:H ratio about 2). Addition of the isolated subunits to toxic fractions generally caused inhibition and only exceptionally potentiation of toxicity.The data suggest that the cholera toxin might consist of an aggregate of seven L and one H subunits while the natural toxoid seems composed of only the aggregated L chains.