Elbow- and hinge-bending motions of IgG: Dielectric response and dynamic feature
Elbow- and hinge-bending motions of IgG: Dielectric response and dynamic feature
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IgG 的肘部和铰链弯曲运动：介电响应和动态特征
DOI：
10.1002/bip.22841
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发表时间：
2016
期刊：
影响因子：
2.9
通讯作者：
Yoshihito Hayashi and Shin. Yagihara
中科院分区：
文献类型：
--
作者：
Fumiya Abe;Akihiro Nishi;Hironobu Saito;Megumi Asano;Seiei Watanabe;Rio Kita;Naoki Shinyashiki;ShiSeiichi Sudo;Youki Suzuki;Yoshihito Hayashi and Shin. Yagihara
免疫球蛋白G（IgG）是一种Y形球状蛋白，由两个Fab片段与具有柔性铰链区的Fc片段连接组成，其中Fab片段在“肘”区显示二级柔性。在目前的工作中，铰链弯曲和肘弯曲运动的IgG水溶液的微波介电测量低于散装水的冰点观察。大分子周围存在的不可冻结的水减少了通常由冰产生的空间位阻的影响，并使IgG的分子内运动成为可能。同时，整体IgG分子旋转受到冰的限制。木瓜蛋白酶消化和铰链区二硫键的还原用于产生Fab和Fc片段。在这些碎片的溶液中，铰链弯曲运动的介电弛豫过程不存在，尽管手肘弯曲运动仍然存在。对于木瓜蛋白酶消化的IgG，观察到三个松弛过程。高频、中频和低频过程分别归因于未冻结水、与结合水合作的局部肽运动和手肘弯曲运动。在完整IgG的情况下，在低于手肘弯曲运动的频率下观察到由于铰链弯曲运动引起的额外松弛过程。© 2016 Wiley Periodicals，Inc. Biopolymers 105：626-632，2016.
Immunoglobulin G (IgG) is a Y‐shaped globular protein consisting of two Fab segments connecting to an Fc segment with a flexible hinge region, in which the Fab segments show secondary flexibility at an “elbow” region. In the present work, the hinge‐bending and elbow‐bending motions of aqueous solutions of IgG by microwave dielectric measurements below the freezing point of bulk water was observed. The presence of unfreezable water around the macromolecules reduced the effects of steric hindrance normally generated by ice and enabled the intramolecular motions of IgG. At the same time, the overall IgG molecule rotation was restricted by ice. Papain digestion and reduction of the disulfide linkage at the hinge region was used to generate Fab and Fc fragments. In solutions of these fragments, the dielectric relaxation process of the hinge‐bending motion was absent, although the elbow‐bending motion remained. Three relaxation processes were observed for papain‐digested IgG. The high, middle, and low frequency processes were attributed to unfrozen water, local peptide motions cooperating with bound water, and the elbow‐bending motion, respectively. In the case of the intact IgG, an additional relaxation process due to the hinge‐bending motion was observed at frequencies lower than that of the elbow‐bending motion. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 626–632, 2016.