AGGREGATION OF WOOL KERATIN INTERMEDIATE FILAMENT PROTEINS
AGGREGATION OF WOOL KERATIN INTERMEDIATE FILAMENT PROTEINS
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DOI：
10.1016/0141-8130(89)90020-2
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发表时间：
1989-10-01
影响因子：
8.2
通讯作者：
WOODS, EF
中科院分区：
文献类型：
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作者：
WOODS, EF
将羊毛角蛋白中间丝蛋白分离为其S-羧甲基衍生物(S-羧甲基角蛋白A.SCMKA)，并通过凝胶过滤纯化，以去除残留的低分子非螺旋蛋白。纯化的SCMKA的α-螺旋含量为apprx。62%与根据亚基的氨基酸序列预测的α-螺旋螺旋卷曲片段的预测一致。在pH为11的水溶液中或在pH为9.2的正丙醇(20%v/v)中，非常大的聚集体被解离，SCMKA主要以二聚体(MR apprx的双链盘绕线圈)的混合物形式存在。103000)和四聚体。从凝胶过滤和沉淀平衡来看，蛋白质物种并不处于快速可逆平衡状态。可能存在具有一定范围的缔合常数的物种。当pH从9.2改变到11或加入20%(v/v)正丙醇时，平衡向二聚体移动。来自角蛋白分子α螺旋杆段1B片段的四聚体蛋白水解物随着pH的增加和正丙醇的存在，以类似于完整的SCMKA的方式分解。这表明了棒状结构域的这一区域在细丝组装的初始阶段的重要性。在完整的SCMKA和1B片段四聚体中，两链螺旋线圈与四聚体的结合涉及静电和疏水相互作用。对从其他中间纤维类型获得的完整的二聚体和四聚体络合物的结果进行了讨论。
The wool keratin intermediate filament proteins were isolated as their S-carboxymethyl derivatives (S-carboxymethylkerateine A.SCMKA) and purified by gel filtration to remove residual non-helical protein of low molecular weight. The .alpha.-helix content of purified SCMKA was .apprx. 62% in agreement with that predicted for the .alpha.-helical coiled-coil segments from the amino acid sequences of the subunits. In aqueous buffer at pH 11 or in n-propanol (20% v/v) at pH 9.2 very large aggregates are dissociated and SCMKA exists largely as a mixture of the dimer (two-chain coiled-coil of Mr .apprx. 103000) and the tetramer. The protein species are not in rapidly reversible equilibrium as judged from gel filtration and sedimentation equilibrium. It is probable that species with a range of association constants are present. The equilibrium is shifted towards the dimer with change of pH from 9.2 to 11 or by the addition of 20% (v/v) n-propanol. The tetrameric proteolytic digestion product which is derived from the 1B segment of the .alpha.-helical rod section of the keratin molecule dissociates in a similar way to intact SCMKA with increase of pH and in the presence of n-propanol. This indicates the importance of this region of the rod domain in the initial stages of the assembly of the filament. Electrostatic and hydrophobic interactions are implicated in the association of the two-chain coiled-coil to the tetramer both in intact SCMKA and the 1B segment tetramer. The results are discussed in relation to the intact dimeric and tetrameric complexes obtained from other intermediate filament types.