甘露聚糖结合凝集素的丝氨酸蛋白酶结合位点初步研究

Preliminary study on serine proteases binding sites on mannan-binding lectin

采用ELISA技术,建立人甘露聚糖结合凝集素(MBL)与MBL相关丝氨酸蛋白酶(MASP)结合的检测体系。设计合成一系列MBL胶原样区(CLR)的相应短肽进行抑制实验,发现MASP结合于MBL分子CLR中一个含16个氨基酸残基的区域,即成熟MBL肽链的第45～60位氨基酸残基,该区域位于Gly-X-Y三联体重复序列中Gly-Gln断裂的C端。还发现分别含1个突变残基的3种突变型(32Cys、34Asp和37Glu)MBL蛋白与MASP的结合具有类似野生型MBL蛋白的特征,但其结合能力明显降低,表明这3个突变残基位于MBL的MASP结合位点之外。

Using the indirect enzyme-linked immunosorbent assay（ELISA）, a system detecting the interaction between human mannan-binding lectin （MBL） and MBL-associated serine proteases （MASPs） was established and a series of collagen like region （CLR） peptides were synthesized, which were assumed to block the MBL-MASP interaction in order to locate the MASPs binding sites on MBL. It was found that MASPs bind to a region of 16 amino acid residues, spanning amino acids 45 to 60 in mature polypeptide of human MBL, locating lies on the C-terminal side of the Gly-Gln interruption in the Gly-X-Y triplet repeat pattern of the collagen like domain. Three mutant MBL proteins, 32Cys, 34Asp and 37Glu MBL proteins, had the similar serine protease binding characteristic with wild type MBL but the binding was much weaker than that between wild type MBL protein and MASPs, demonstrating that these mutations locate outside the binding sites for MASPs.