Substructure of myosin subfragment-1 as revealed by digestion with proteolytic enzymes.
Substructure of myosin subfragment-1 as revealed by digestion with proteolytic enzymes.
复制标题
通过蛋白水解酶消化揭示肌球蛋白亚片段 1 的亚结构。
DOI：
10.1093/oxfordjournals.jbchem.a132728
复制
发表时间：
1980
影响因子：
2.7
通讯作者：
T. Sekine
中科院分区：
文献类型：
--
作者：
K. Yamamoto;T. Sekine
为了阐明肌球蛋白亚片段-1的子结构，我们用胰蛋白酶和木瓜蛋白酶消化它，并确定其重链和轻链容易被这些蛋白水解酶攻击的位点。研究发现，距N端约96K的区域很容易受到胰蛋白酶、胰凝乳蛋白酶和木瓜蛋白酶的攻击。由于这些酶的特异性差异很大，该区域可能具有特殊的结构，并且它似乎位于subfragment-1和杆之间的柔性铰链处。发现该区域的敏感性与 DTNB 轻链的存在之间存在密切关系。结果表明 DTNB 轻链的某些部分与该区域的 subfragment-1 相关。发现与 N 末端相距约 26 K 的另一个区域很容易受到胰蛋白酶和木瓜蛋白酶的攻击。由于木瓜蛋白酶具有广泛的特异性，因此该区域似乎也具有一些特殊的结构，可以轻松访问酶。碱性轻链 1 被木瓜蛋白酶和胰蛋白酶降解为大约 23 K 的片段，而碱性轻链 2 对这些酶具有抗性。结果表明，木瓜蛋白酶和胰蛋白酶攻击的位点位于碱金属轻链1的N端额外肽中。当胰蛋白酶将DTNB轻链降解为大约17K片段时，Cys 157并未从DTNB轻链上解离。这意味着胰蛋白酶没有攻击轻链的第 154 位赖氨酸。因此，表明胰蛋白酶在产生 17 K 片段时会攻击 Arg 7 和 Lys 166。
To elucidate the substructure of myosin subfragment-1, we digested it with trypsin and papain and determined the sites of its heavy chain and light chains which were readily attacked by these proteolytic enzymes. It was found that a region separated from the N-terminal by about 96 K was easily attacked by trypsin, chymotrypsin, and papain. Since the specificities of these enzymes are quite different, the region may have a special structure, and it seems to be located at the flexible hinge between subfragment-1 and the rod. A close relation between the susceptibility of the region and the presence of DTNB light chain was found. The result suggests that some portion of the DTNB light chain is associated with subfragment-1 at this region. Another region separated from the N-terminal by about 26 K was found to be attacked readily by trypsin and papain. Since papain has a broad specificity, the region also seems to have some special structure which allows easy access of the enzyme. Alkali light chain 1 was degraded to a roughly 23 K fragment by both papain and trypsin, whereas alkali light chain 2 was resistant to these enzymes. The results indicate that the sites attacked by papain and trypsin were located in the N-terminal extra peptide of alkali light chain 1. When DTNB light chain was degraded to a roughly 17 K fragment by trypsin, Cys 157 was not dissociated from the DTNB light chain. This means that trypsin did not attack Lys 154 of the light chain. It is suggested, therefore, that trypsin attacked both Arg 7 and Lys 166 when it produced the 17 K fragment.