Unstable inter-H chain disulfide bonding and non-covalently associated J chain in rat dimeric IgA.
Unstable inter-H chain disulfide bonding and non-covalently associated J chain in rat dimeric IgA.
复制标题
大鼠二聚体 IgA 中不稳定的 H 链间二硫键和非共价连接的 J 链。
DOI：
10.1016/0161-5890(93)90422-8
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发表时间：
1993
影响因子：
3.6
通讯作者：
Kaetzel,CS
中科院分区：
文献类型：
--
作者：
Chintalacharuvu,KR;Lamm,ME;Kaetzel,CS
二硫键是稳定免疫球蛋白三维结构的主要力量。为了确定大鼠二聚体伊加（dIgA）的四条H链、四条L链和一条J链之间的链间二硫键结合模式，我们通过对角SDS-PAGE分析了来自LO DNP-64杂交瘤的dIgA。在非还原条件下观察到对应于一条、两条、三条和四条H链、一条和两条L链以及游离J链的条带，表明大鼠dIgA中的链间二硫键在变性条件下不稳定。在来自LOU/CN大鼠的其他三种杂交瘤或骨髓瘤dIgA中观察到类似的二硫键模式。相比之下，当通过相同的技术分析用碘乙酰胺（IA）预处理的dIgA时，仅观察到对应于四条H链、一条和两条L链以及游离J链的条带，这表明阻断游离巯基稳定了H链间二硫键。二聚LO DNP-64 dIgA与5，5 ′-二硫代双-（2-硝基苯甲酸）或与14 C-IA的反应表明，在非变性条件下，该dIgA每摩尔蛋白质平均含有4摩尔游离巯基，在变性条件下，每摩尔蛋白质平均含有9摩尔游离巯基。两者合计，结果表明，大鼠dIgA中的链间二硫键是不稳定的，大概是由于附近的游离巯基的影响，并且非共价力对于稳定dIgA复合物是至关重要的。结果还表明J链与H链完全非共价结合，这是大鼠dIgA的明显独特特征。提出了大鼠dIgA链间二硫键模型。
Disulfide bonds are a major force in stabilizing the three-dimensional structure of immunoglobulins. To determine the pattern of interchain disulfide bonding between the four H chains, four L chains and single J chain of rat dimeric IgA (dIgA), we analyzed dIgA from the LO DNP-64 hybridoma by diagonal SDS-PAGE. Bands corresponding to one, two, three and four H chains, one and two L chains and the free J chain were observed under non-reducing conditions, suggesting that the interchain disulfide bonds in rat dIgA are unstable under denaturing conditions. Similar patterns of disulfide bonding were observed in three other hybridoma or myeloma dIgAs from LOU/CN rats. In contrast, when dIgA pretreated with iodoacetamide (IA) was analyzed by the same technique, only bands corresponding to four H chains, one and two L chains and the free J chain were observed, suggesting that blocking free sulfhydryl groups stabilizes the inter-H chain disulfide bonds. Reaction of dimeric LO DNP-64 dIgA with 5,5'-dithiobis-(2-nitrobenzoic acid) or with14C-IA demonstrated that this dIgA contains an average of 4 moles of free sulfhydryl groups per mole of protein under non-denaturing conditions and 9 moles of free sulfhydryl groups under denaturing conditions. Taken together, the results suggest that interchain disulfide bonds in rat dIgA are unstable, presumably due to the influence of nearby free sulfhydryl groups, and that non-covalent forces are critical for stabilizing the dIgA complex. The results also indicate that J chain is entirely non-covalently associatd with the H chains, an apparently unique feature of rat dIgA. A model for interchain disulfide bonding in rat dIgA is proposed.