Reduction of a disulfide bond of thrombospondin in the supernatant solution of activated platelets.
Reduction of a disulfide bond of thrombospondin in the supernatant solution of activated platelets.
复制标题
活化血小板上清液中血小板反应蛋白二硫键的还原。
DOI：
10.1016/0003-9861(91)90077-v
复制
发表时间：
1991
影响因子：
3.9
通讯作者：
Detwiler,TC
中科院分区：
文献类型：
--
作者：
Speziale,MV;Detwiler,TC
活化血小板分泌的物质的孵育导致形成二硫键连接的二聚体和多聚体的蛋白质之一，血小板反应蛋白。为了确定这些复合物是由于硫醇-二硫键交换（硫醇数量无变化）还是由于硫醇氧化（硫醇数量减少）而形成的，在多聚体形成期间测量TSP中的硫醇数量。硫醇的数量从约3个/mol增加到4.8个/mol。血小板反应蛋白单体消失的半衰期是新硫醇出现的半衰期的四倍。新的巯基的出现，以及多聚体的形成，被抑制的Ca 2+。新的硫醇的出现是可逆的;另外的Ca 2+逆转了该过程，并且在pH 8下，但不是在pH 6或7下，新的硫醇的出现自发逆转。在孵育部分纯化的血小板反应蛋白期间或在用活化的硫醇-琼脂糖凝胶处理上清液以除去反应性硫醇化合物之后，没有形成新的硫醇。它的结论是，血小板反应蛋白具有二硫键，是不稳定的情况下的Ca 2+。它可以被另一个血小板反应蛋白分子的硫醇攻击以形成二硫键连接的多聚体，被同一个血小板反应蛋白分子的硫醇攻击以产生二硫键的异构化，或者如本研究中所观察到的，被另一种分泌的硫醇化合物攻击以产生混合的二硫化物和新的硫醇。
Incubation of the material secreted by activated platelets leads to the formation of disulfide-linked dimers and multimers of one of the proteins, thrombospondin. To determine whether these complexes formed as a result of thiol-disulfide exchange (no change in the number of thiols) or of oxidation of thiols (a decrease in the number of thiols), the number of thiols in TSP was measured during formation of multimers. The number of thiols increased from about 3/mol to 4.8/mol. The half-time for the disappearance of monomers of thrombospondin was fourfold greater than the half-time for appearance of new thiols. The appearance of new thiols, as well as the formation of multimers, was inhibited by Ca2+. The appearance of new thiols was reversible; addition of Ca2+reversed the process, and at pH 8, but not at pH 6 or 7, the appearance of new thiols spontaneously reversed. No new thiols formed during incubation of partially purified thrombospondin or after the supernatant solution had been treated with activated thiol-Sepharose to remove reactive thiol compounds. It is concluded that thrombospondin has a disulfide bond that is unstable in the absence of Ca2+. It can be attacked by a thiol of another molecule of thrombospondin to form disulflde-linked multimers, by a thiol of the same molecule of thrombospondin to generate isomerization of disulfide bonds or, as observed in this study, by another secreted thiol compound to give a mixed disulfide and a new thiol.