Product Description

C3/C5-Depleted Serum is normal human serum in which C3 and C5 have been removed by immunoaffinity chromatography. The product is tested for the absence of C3 and C5 activity by testing classical and alternative pathway function and for the absence of C3 and C5 proteins by double immunodiffusion. The C3/C5-depleted serum is certified to exhibit less than 5% classical pathway and alternative pathway activities. Functional classical and alternative pathways can be reconstituted by addition of purified C3 protein (1.3 mg/mL) and C5 protein (75 ug/mL) indicating that all other complement components necessary for classical and alternative pathway activation are present. After reconstitution with C3 (1.3 mg C3/mL) and C5 (0.75 mg/mL), the C3/C5-Depleted Serum is certified to possess a functional classical and alternative pathway for complement activation (Morgan, B.P. (2000); Dodds, A.W. and Sim, R.B. (1997)). Although a functional lectin pathway should also be reconstituted by the addition of similar concentrations of C3 and C5, the function of this pathway is not tested.

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Complement Technology的C1是级联反应中的第一个补体成分，称为补体经典途径。C1与抗原结合的抗体（免疫复合物）结合并被其激活，从而产生引发级联反应的蛋白酶。C1实际上是钙依赖性复合物中结合在一起的三种不同蛋白质（C1q，C1r和C1s）的非共价复合物。C1q通过其六个臂中的两个或多个与IgG或IgM的Fc结构域结合。多臂与免疫复合物的结合被认为会引入压力，从而导致复合物中的两个C1r蛋白（蛋白酶酶原）自身激活，从而产生两种活性的C1r丝氨酸蛋白酶（Morikis，D.和Lambris，JD（2005））。 。这些激活的C1r亚基裂解并激活复合物中的两个C1s蛋白酶酶原。活化的C1裂解补体成分C4，释放出C4a，并启动C4b与活化表面的共价连接。活化的C1也切割C2，并且C2的较大片段结合至表面附着的C4b，形成C4b，C2a，其为经典途径的C3 / C5转化酶。