MECHANISM OF ACTION OF FACTOR-D OF ALTERNATIVE COMPLEMENT PATHWAY
MECHANISM OF ACTION OF FACTOR-D OF ALTERNATIVE COMPLEMENT PATHWAY
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DOI：
10.1084/jem.148.6.1498
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发表时间：
1978-01-01
影响因子：
15.3
通讯作者：
MULLEREBERHARD, HJ
中科院分区：
文献类型：
--
作者：
LESAVRE, PH;MULLEREBERHARD, HJ
人血清的因子 D（C3 [补体成分 3] 前激活剂转化酶）对于旁路途径功能、激活该途径的 C3/C5 转化酶绝对是必需的，并且不是该酶的亚基。因子D仅以活性形式存在于人血浆中，浓度为2μg/ml，并且不受血浆蛋白酶抑制剂或自发衰变的控制。与胰蛋白酶不同，因子 D 仅当因子 B 与 C3b 形成 Mg2+ 依赖性复合物时才裂解并激活因子 B，不具有酯解活性，并且无法裂解胰岛素的 B 链。所声称的 D 因子与 α-凝血酶的功能和抗原关系无法得到证实。根据隐秘位点假说描述了因子 D 的作用机制。
Factor D (C3 [complement component 3] proactivator convertase) of human serum was absolutely necessary for alternative pathway function, for activation of the C3/C5 convertase of that pathway and was not a subunit of this enzyme. Factor D was present in human plasma in active form only, at a concentration of 2 .mu.g/ml, and was not controlled by plasma protease inhibitors or by spontaneous decay. Unlike trypsin, factor D cleaves and activates factor B only when it is in Mg2+-dependent complex with C3b, has no esterolytic activity and is unable to cleave the B chain of insulin. The alleged functional and antigenic relationship of factor D to .alpha.-thrombin could not be verified. The mechanism of action of factor D in terms of the cryptic site hypothesis is described.