Perkins S J, Smith K F
Department of Biochemistry and Chemistry, Royal Free Hospital School of Medicine, London, U.K.
Biochem J. 1993 Oct 1;295 ( Pt 1)(Pt 1):109-14. doi: 10.1042/bj2950109.
The serine-proteinase domain is responsible for the proteolytic events that occur during complement activation. The sequences of nine serine proteinases of known crystal structure were compared with the serine-proteinase sequences in the six complement proteins C1r, C1s, C2, factor B, factor I and factor D to assess the degree of structural homology of the latter with the crystal structures. All sequence insertions and deletions were readily located at the protein surface. The internal location of disulphide bridges and the surface location of putative glycosylation sites are compatible with this structure. Secondary-structure predictions for the sequences were fully consistent with the crystal structures. It is concluded that the double subdomain beta-sheet motif is retained in the complement sequences, but that localized differences are observed for factor I, C2 and factor B.
丝氨酸蛋白酶结构域负责补体激活过程中发生的蛋白水解事件。将已知晶体结构的九种丝氨酸蛋白酶的序列与六种补体蛋白C1r、C1s、C2、B因子、I因子和D因子中的丝氨酸蛋白酶序列进行比较，以评估后者与晶体结构的结构同源程度。所有的序列插入和缺失都很容易定位在蛋白质表面。二硫键的内部位置和假定糖基化位点的表面位置与该结构相符。对这些序列的二级结构预测与晶体结构完全一致。结论是，双亚结构域β-折叠基序在补体序列中得以保留，但在I因子、C2和B因子中观察到局部差异。
