Schumaker V N, Calcott M A, Spiegelberg H L, Müller-Eberhard H J
Biochemistry. 1976 Nov 16;15(23):5175-81. doi: 10.1021/bi00668a035.
Normal IgG and myeloma proteins of the IgG1, 2, 3,and 4 subclasses were mixed with human Clq and studied in the analytical ultracentrifuge for complex formation. Binding of IgG to Clq is apparent both from the enlargement of area and from the increase in sedimentation rate of the well-separated schlieren peak of Clq. The accurate determination of binding parameters requires that sedimentation rates be corrected for hydrodynamic interaction, and area measurements corrected for the Johnston-Ogston effect. At the highest immunoglobulin concentrations employed in these studies more than ten IgG molecules are bound to each Clq. If we assume that the number of binding sites must be an integral multiple of 6, then the data best support a 12 binding site model, although an 18 site model cannot be rule out. Myeloma IgG proteins of all subclasses bind to Clq, with affinities decreasing in the order G3 greater than G1 greater than G2 greater than G4. No binding of IgA to Clq could be detected.
将正常IgG以及IgG1、IgG2、IgG3和IgG4亚类的骨髓瘤蛋白与人Clq混合，并在分析超速离心机中研究复合物的形成。从面积增大以及Clq清晰可辨的schlieren峰沉降速率增加都可以明显看出IgG与Clq的结合。准确测定结合参数需要对沉降速率进行流体动力学相互作用校正，对面积测量进行约翰斯顿 - 奥格斯顿效应校正。在这些研究中使用的最高免疫球蛋白浓度下，每个Clq结合了超过十个IgG分子。如果我们假设结合位点的数量必须是6的整数倍，那么数据最支持12个结合位点模型，尽管18个位点模型也不能排除。所有亚类的骨髓瘤IgG蛋白都与Clq结合，亲和力按G3大于G1大于G2大于G4的顺序降低。未检测到IgA与Clq的结合。
