Kinetic studies on the fragmentation of the third component of complement (C3) by trypsin.
Kinetic studies on the fragmentation of the third component of complement (C3) by trypsin.
复制标题
胰蛋白酶裂解补体第三组分（C3）的动力学研究。
作者：
J. Minta;D. Man;H. Movat
胰蛋白酶裂解的C3的动力学进行了分析，通过琼脂糖电泳和聚丙烯酰胺凝胶中含有十二烷基硫酸钠和所获得的数据被用来构建一个解剖模型C3显示胰蛋白酶攻击的网站，所产生的片段，和它们的组成。胰蛋白酶显示以逐步方式裂解C3。攻击最初针对α-多肽链，并导致C3 a和C3 b的产生。进一步裂解C3 b的α链，将其转化为C3 b1，然后转化为C3 d和C3 c。胰蛋白酶对β链的切割仅发生在C3 c阶段，并释放出小肽（m.w. 12，000）和C3 c '的形成。在免疫电泳中，C3 c '的阳极迁移率低于C3 c的β 1A迁移率。C3 a一旦形成，就可以进一步裂解以得到具有减少的净正电荷的残余片段。将C3暴露于pH 5.0或以下的酸性条件下，使该分子对胰蛋白酶降解极其敏感。
The kinetics of cleavage of C3 by trypsin was analyzed by electrophoresis in agarose and in polyacrylamide gels containing sodium dodecyl sulfate and the data obtained were used to construct an anatomical model for C3 showing the sites of tryptic attack, the fragments generated, and their composition. Trypsin was shown to cleave C3 in a stepwise fashion. The attack was initially directed at the alpha-polypeptide chain and resulted in the generation of C3a and C3b. Further cleavage of the alpha-chain of C3b, converted it into C3b1 and then into C3d and C3c. Cleavage of the beta-chain by trypsin occurred only at the C3c stage with the release of a small peptide (m.w. 12,000) from C3c and the formation of C3c'. On immunoelectrophoresis, C3c' had a less anodal mobility compared to the beta1A mobility of C3c. C3a, once formed could be further cleaved to give residual fragments with decreasing net positive charge. Exposure of C3 to acid conditions, pH 5.0 or below, rendered the molecule exceedingly susceptible to tryptic degradation.