Solid-state NMR studies on the supersecondary structures in fibrous proteins

纤维蛋白超二级结构的固态核磁共振研究

• 批准号: 07651103
• 负责人: YOSHIMIZU Hiroaki
• 金额: $ 1.6万
• 依托单位: Nagoya Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07651103/
• 关键词: fibrous proteins; supeseconday structures; coild-coil structure; alpha-helix; conformation; soild-state NMR; chemical shift; wool keratin

^<13>C CP/MAS NMR spectra of tropomyosin were measured in order to elucidate the higher order structure through the ^<13>C NMR chemical shifts of the amino acid residues and their mobility. The higher order structure of tropomyosin is a coiled-coil structure, and contains two different sites which are characterized as the internal and external sites. The ^<13>C signal which appear at 15-17 ppm can be easily assigned to the Ala C^<beta> carbons, and it can be seen that this signal was consisted of two peaks. The peak at 15.8 ppm have a longer T_1 value than those at 16.7 ppm. This is indicated that the former carbons are more mobile than the latter carbons. Therefore, the two peaks at 15.8 and 16.7 ppm are assigned to the Ala C^<beta> carbons in the extermal and internal sites of the coiled-coil structure, respectively. Wool keratin can be divided into three main fractions after reducing disulfide bonds and protection of the resulting thiol groups with iodoacetic acid to form S-carboxymethyl kerateine (SCMK). From the ^<13>C CP/MAS NMR spectra of wool and SCMK,it was suggested that the coiled-coil structure exists because the ^<13>C chemical shift values of Ala C^<beta> carbons in these samples coincide in experimental error with that of the Ala residue located in the internal site of the coiled-coil structure in tropomyosin. The conformational analysis using the conformation-dependent ^<13>C CP/MAS NMR chemical shifts were applied to estimate the conformational transition of SCMK by stretching, heating, or steam-treating. The beta-sheet form appears by stretching and steam-treating. For the heated SCMK,it can be said that the random coil form appears. However, the fact that the a-helix form remains to an appreciable extent in the heated one although the random coil form appears, suggests that only the packing of the coiled-coil structure in the SCMK is disrupted by heating, but secondary structure being retained.

为了通过氨基酸残基的 ^<13> c NMR化学移位及其迁移率阐明tropomyosin的 ^<13> c cp/mas nmr光谱。 tropomyosin的高阶结构是一种盘绕的线圈结构，包含两个不同的位点，这些位点被描述为内部和外部位点。出现在15-17 ppm处的 ^<13> C信号可以轻松分配给ALA C ^<beta>碳，并且可以看出该信号由两个峰组成。 15.8 ppm时的峰值比16.7 ppm的峰值更长。这表明以前的碳比后一种碳更容易移动。因此，分别分别将两个峰和16.7 ppm的峰分别分配给盘绕螺旋结构的外部和内部位点的Ala C^<beta>。羊毛角蛋白可以在还原二硫键和用碘乙酸的硫醇基团的保护后分为三个主要部分，形成S-羧甲基甲酯（SCMK）。从羊毛和SCMK的 ^<13> c cp/mas nmr光谱中，建议存在盘绕螺旋结构，因为这些样品中Ala c ^<beta>碳的化学位移值在这些样品中的化学移位值与位于曲菌素结构内部内部结构内部位置的Ala残基的实验误差重合。使用依赖构象的 ^<13> c CP/MAS NMR化学位移的构象分析通过拉伸，加热或蒸汽处理来估计SCMK的构象过渡。 beta表格通过拉伸和蒸汽处理而出现。对于加热的SCMK，可以说出现随机线圈形式。但是，尽管出现随机线圈形式，但A螺旋形式在加热的范围内仍具有明显的程度，这表明只有SCMK中盘绕螺旋结构的堆积被加热破坏，但保留了二级结构。

项目成果

高分子学会編: "高分子実験学5 高分子の構造(1)磁気共鳴法" 共立出版株式会社, 572 (1995)

高分子学会编：《高分子实验5：高分子的结构(1)磁共振法》共立出版572(1995)

Hiroaki Yoshimizu: Section 4.5.1 in "The Structures of Polymers (1) Hagnetic Resonance Spectroscopy". Edited by the Sociery of Polymer Science, Japan, Kyoritsu Shuppan Co.Ltd., (1995)

Hiroaki Yoshimizu：《聚合物的结构（1）共振光谱》第4.5.1节。