Department of Physics, Urbana, IL 61801, USA.
Annu Rev Biophys. 2011;40:187-203. doi: 10.1146/annurev-biophys-072110-125325.
This review uses the giant muscle protein titin as an example to showcase the capability of molecular dynamics simulations. Titin is responsible for the passive elasticity in muscle and is a chain composed of immunoglobulin (Ig)-like and fibronectin III (FN-III)-like domains, as well as PEVK segments rich in proline (P), glutamate (E), valine (V), and lysine (K). The elasticity of titin is derived in stages of extension under increasing external force: Ig domain straightening occurs first (termed tertiary structure elasticity), followed by the extension of the disordered PEVK segments. At larger extension and force, Ig domains unfold one by one (termed secondary structure elasticity). With the availability of crystal structures of single and connected Ig domains, the tertiary and secondary structure elasticity of titin was investigated through molecular dynamics simulations, unveiling the molecular origin of titin's elasticity.
本文以巨大肌肉蛋白titin 为例，展示了分子动力学模拟的能力。Tit in 负责肌肉的被动弹性，是由免疫球蛋白（Ig）样和纤维连接蛋白 III（FN-III）样结构域以及富含脯氨酸（P）、谷氨酸（E）、缬氨酸（V）和赖氨酸（K）的 PEVK 片段组成的链。Tit in 的弹性是在外力增加下分阶段伸展的结果：首先是 Ig 结构域变直（称为三级结构弹性），然后是无序的 PEVK 片段的伸展。在更大的伸展和力作用下，Ig 结构域逐个展开（称为二级结构弹性）。由于单连接和多连接 Ig 结构域的晶体结构可用，通过分子动力学模拟研究了 titin 的三级和二级结构弹性，揭示了 titin 弹性的分子起源。
