Politou A S, Thomas D J, Pastore A
European Molecular Biology Laboratory, Heidelberg, Germany.
Biophys J. 1995 Dec;69(6):2601-10. doi: 10.1016/S0006-3495(95)80131-1.
Titin (first known as connectin) is a vast modular protein found in vertebrate striated muscle. It is thought to assist myofibrillogenesis and to provide a passive elastic restoring force that helps to keep the thick filaments properly centered in the sarcomere. We show that representative titin modules do indeed fold independently, and report their stabilities (i.e., delta G of unfolding and melting temperature) as measured by circular dichroism, fluorescence, and nuclear magnetic resonance spectroscopies. We find that there is a region-dependent variation in stability, although we find no evidence to support a proposed elastic mechanism based on a molten-globular-like equilibrium folding intermediate, nor do our calculations support any mechanism based on the configurational entropy of the molecule itself; instead we suggest a model based on hydrophobic hinge regions that would not be strongly dependent on the precise folding pattern of the chain.
肌联蛋白（最初称为连接蛋白）是一种在脊椎动物横纹肌中发现的巨大模块化蛋白质。它被认为有助于肌原纤维的形成，并提供一种被动弹性恢复力，有助于使粗肌丝在肌节中正确居中。我们表明，代表性的肌联蛋白模块确实能独立折叠，并报告了通过圆二色性、荧光和核磁共振光谱法测量的它们的稳定性（即解折叠的ΔG和熔解温度）。我们发现稳定性存在区域依赖性变化，尽管我们没有找到证据支持基于类似熔球态平衡折叠中间体的拟弹性机制，我们的计算也不支持基于分子本身构象熵的任何机制；相反，我们提出了一个基于疏水铰链区的模型，该模型不会强烈依赖于链的精确折叠模式。
