Götze O, Müller-Eberhard H J
J Exp Med. 1974 Jan 1;139(1):44-57. doi: 10.1084/jem.139.1.44.
Properdin (P), a highly basic euglobulin, was purified from human serum to molecular homogeneity without the use of zymosan. Isolated P was found to efficiently initiate activation of the alternate pathway of complement activation (C3 activator or properdin system) and to be an essential component during its early reaction stages. The activity of isolated P did not require the presence of an activating polysaccharide. It was therefore concluded that purified P had been obtained in an activated form (P). In an isolated reaction system containing purified C3, C3 proactivator (C3PA), and C3 proactivator convertase (C3PAse), P was able to mediate the activation of C3PAse which in turn activated C3PA to cleave C3. This activation of C3PAse was found to depend on the presence of native C3. These results allowed the formulation of a concept in which P is envisaged to act as a modulator of native C3 enabling it to activate C3PAse. Activation of C3 was efficiently mediated by P in the fluid phase. Efficient activation of C5, however, required the participation of an insoluble polysaccharide (zymosan). The possibility is raised therefore that P might also be an integral part of the multimolecular C5 convertase of the alternate pathway of complement activation.
备解素（P）是一种高度碱性的优球蛋白，在不使用酵母聚糖的情况下从人血清中纯化至分子均一性。发现分离出的P能有效启动补体激活替代途径（C3激活剂或备解素系统）的激活，并且是其早期反应阶段的必需成分。分离出的P的活性不需要存在激活多糖。因此得出结论，已获得以活化形式（P）存在的纯化的P。在含有纯化的C3、C3前激活剂（C3PA）和C3前激活剂转化酶（C3PAse）的分离反应系统中，P能够介导C3PAse的激活，而C3PAse又激活C3PA以裂解C3。发现C3PAse的这种激活取决于天然C3的存在。这些结果使得能够形成一个概念，即设想P作为天然C3的调节剂，使其能够激活C3PAse。在液相中，P有效地介导了C3的激活。然而，C5的有效激活需要不溶性多糖（酵母聚糖）的参与。因此提出了一种可能性，即P也可能是补体激活替代途径的多分子C5转化酶的一个组成部分。
