Abstract

In this paper, the property of the muscle titin protein to form in vitro specific amyloid-like aggregates is discussed. The main difference from the known amyloid aggregates is the formation of a quaternary structure that resembles cross-β, with no changes in the secondary structure. Based on the results obtained earlier, as well as the results of this study, we make assumptions about changes in the structure of titin that occur during the formation of amyloid-like aggregates. In particular, our X-ray diffraction data on the titin aggregates suggest that β-strands in the aggregates of this protein are not located perpendicular to the fibril axis, as described for other amyloid proteins, but in parallel. The distance between the β-sheets in the aggregates may vary, and the β-sheets themselves are not strictly oriented along one of the axes, which can lead to the appearance of a diffuse ring reflection of ~8–12 Å. In this regard, the titin aggregates should not be called amyloid, but amyloid-like, with a quaternary structure that resembles cross-β. It cannot be excluded that the formation of this quaternary structure can also occur due to the partial unfolding of titin domains, followed by the interaction of open β-strands between neighboring domains and/or domains of neighboring molecules.

中文翻译：

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聚集过程中钛结构的变化

摘要

在本文中，讨论了肌纤蛋白形成体外特异性淀粉样蛋白聚集体的特性。与已知的淀粉样蛋白聚集体的主要区别是类似于十字β的四级结构的形成，二级结构没有变化。基于较早获得的结果以及本研究的结果，我们对淀粉样蛋白聚集体形成过程中发生的替丁结构变化进行了假设。尤其是，我们在纤维蛋白聚集体上的X射线衍射数据表明，该蛋白聚集体中的β链不像其他淀粉样蛋白所描述的那样垂直于原纤维轴定位，而是平行排列。聚集体中β片之间的距离可能会有所不同，并且β片本身并非严格沿其中一个轴定向，这可能导致出现〜8–12Å的扩散环反射。就这一点而言，钛蛋白聚集体不应被称为淀粉样蛋白，而应被称为淀粉样蛋白，具有类似于交叉β的四级结构。不能排除由于季铵盐结构域的部分展开，随后相邻域和/或相邻分子域之间的开放β链相互作用，也可能发生这种四元结构。