総説

重水素交換NMR分光法による
タンパク質立体構造の揺らぎの研究

A Hydrogen-Exchange NMR Study of Structural Fluctuations of Protein

野田 康夫・飯村 哲史・瀬川 新一
Yasuo NODA, Satoshi IIMURA, and Shin-ichi SEGAWA

タンパク質の立体構造の揺らぎを原子レベルの分解能で知るために、主鎖アミドプロトンの重水素交換反応を２次元ＮＭＲ法と組み合わせて測定することは便利でユニークな測定方法である。S-S結合を系統的に欠損させたリゾチーム変異体の研究を実例として、重水素交換ＮＭＲ法の基礎と応用について述べた。最後に、折りたたみ反応の過渡状態を調べるパルス重水素ラベル法や非天然状態にあるタンパク質を研究するための重水素交換ＮＭＲ法についても触れている。

The NMR structure determination method is well established as a powerful tool in protein research, but an amide hydrogen-exchange NMR is also a unique approach, providing important information on structural fluctuations in protein at the resolution of an individual residue. Here we survey hydrogen-deuterium (H-D) exchange NMR studies on protein dynamics and folding. The purpose of this article is to explain what the H-D exchange NMR method is, and to demonstrate how to obtain information about protein dynamics from such experiments. H-D exchange NMR experiments for lysozyme variants lacking some of the disulfide bridges are reviewed as an example of studies. In addition, recent developments in H-D exchange NMR methods are surveyed with concern about pulsed hydrogen-exchange labeling to detect kinetic folding intermediates. Finally, we describe our challenge to study structurally blocked hydrogens in lysozyme variants in the non-native state by using the H-D exchange NMR method.

Keywords:Hydrogen-exchange, Protection factor, Activation enthalpy, Protein folding, Fluctuation