A genetically engineered human IgG with limited flexibility fully initiates cytolysis via complement.
A genetically engineered human IgG with limited flexibility fully initiates cytolysis via complement.
复制标题
灵活性有限的基因工程人类 IgG 可通过补体完全启动细胞溶解。
DOI：
10.1016/0161-5890(93)90035-a
复制
发表时间：
1993
影响因子：
3.6
通讯作者：
Shopes,B
中科院分区：
文献类型：
--
作者：
Shopes,B
抗原诱导的构象变化和功能活性之间的因果关系先前已被提出用于触发免疫球蛋白效应子功能。为了检验这一假设，已经通过定点诱变产生了具有极大限制的Fab柔性的免疫球蛋白。丝氨酸119是小鼠-人嵌合免疫球蛋白的第一重链恒定结构域中手肘的残基，被半胱氨酸119取代。所得突变免疫球蛋白具有连接两条重链的额外分子内二硫键。这种新引入的抗原结合臂之间的共价键产生了紧凑的“拴系”构象，其显示降低的片段柔性，如通过纳秒荧光去极化各向异性所确定的。然而，这种拴系的免疫球蛋白通过补体级联启动靶细胞裂解的能力未受损。因此，可能的是，需要Fab的不受阻碍的“扭曲”和/或“摆动”运动的构象变化诱导补体活化的变构或畸变机制是站不住脚的。
A causal link between antigen induced conformational change and functional activity has been previously suggested for the triggering of immunoglobulin effector functions. To test this hypothesis an immunoglobulin with greatly restricted Fab flexibility has been created by site-directed mutagenesis. Serine119, a residue at the elbow in the first heavy chain constant domain of a mouse-human chimeric immunoglobulin, was replaced by cysteine119. The resulting mutant immunoglobulin had an additional intramolecular disulfide bond connecting the two heavy chains. This newly introduced covalent bond between antigen binding arms gave rise to a compact ‘tethered’ conformation which displayed lowered segmental flexibility as determined by nanosecond fluorescence depolarization anisotropy. However, the ability of this tethered immunoglobulin to initiate lysis of target cells via the complement cascade was unimpaired. Therefore, it is likely that allosteric or distortive mechanisms of conformational change induced complement activation which require unhindered ‘twist’ and/or ‘waggle’ motions of Fab are untenable.