Farries T C, Finch J T, Lachmann P J, Harrison R A
Biochem J. 1987 Apr 15;243(2):507-17. doi: 10.1042/bj2430507.
A rapid and reproducible procedure for the resolution of 'native' and 'activated' forms of properdin (a component of the alternative activation pathway of complement), by gel filtration on the polyvinyl matrix Fractogel TSK HW-55(S), is reported. This fractionation permitted effective screening of samples for conditions that cause activation. Only 'native' properdin was detected in serum, even after activation of the alternative pathway by yeast cell walls. Transformation of 'native' into 'activated' properdin in vitro was produced by freeze-thawing of the protein, but not upon binding to and dissociation from the C3 convertase, C3bBb. Electron microscopy showed that only the 'native' population contained the discrete cyclic structures described previously by Smith, Pangburn, Vogel & Müller-Eberhard [(1984) J. Biol. Chem. 259, 4582-4588]. 'Activated' properdin, which was eluted from the gel-filtration column close to the breakthrough peak, was mainly composed of large amorphous aggregates. We therefore conclude that properdin 'activation' is not a physiological event that occurs in serum on complement activation, but is an artifact of isolation. Fractionation of properdin on Fractogel TSK HW-55(S) has, however, enabled detailed analysis of functional heterogeneity within the 'native' population.
本文报道了一种通过在聚乙烯基质Fractogel TSK HW-55(S)上进行凝胶过滤来分离备解素（补体替代激活途径的一个组分）“天然”形式和“活化”形式的快速且可重复的方法。这种分级分离允许对样品进行有效筛选，以寻找导致激活的条件。即使在酵母细胞壁激活替代途径后，血清中也仅检测到“天然”备解素。蛋白质的冻融可在体外将“天然”备解素转化为“活化”备解素，但与C3转化酶C3bBb结合和解离时则不会。电子显微镜显示，只有“天然”群体含有Smith、Pangburn、Vogel和Müller-Eberhard先前描述的离散环状结构[（1984年）《生物化学杂志》259, 4582 - 4588]。从凝胶过滤柱上靠近穿透峰处洗脱的“活化”备解素主要由大的无定形聚集体组成。因此，我们得出结论，备解素“激活”不是补体激活时血清中发生的生理事件，而是分离过程中的人为现象。然而，在Fractogel TSK HW-55(S)上对备解素进行分级分离，能够对“天然”群体内的功能异质性进行详细分析。
