以磁偶極作用力為基礎發展生物固態核磁共振之脈衝序列

Abstract

本研究工作是以磁偶極作用力為基礎進行生物固態核磁共振的研發及測量生物分子的二面角(dihedral angles)。論文的第一章將回顧固態核磁共振技術於生物分子結構的測定，第二章則簡單介紹固態核磁共振的理論背景。而本論文的主要內容包含三個研究主題，其一是脈衝序列的內部對稱性(internal symmetry)及其相對應的選擇律(selection rules)。我們利用所推導出來的內部對稱性理論來討論C-REDOR序列抑制同核偶極作用(homonuclear dipole-dipole interaction)的能力，進一步我們再利用脈衝內部對稱性的概念來提升該序列於實驗中的表現。另一研究主題是設計一脈衝序列並將其應用於同核偶極作用回耦(homonuclear dipolar recoupling)。最後我們藉由13C(alpha)-1H(alpha)及13C(alpha)-14N兩個異核偶極張量(heteronuclear dipolar tensors)之間的相互關係來進行生物分子的psi角測量。

This work contains the development of pulse sequences in solid-state NMR and dihedral angle determination of biological solids based on magnetic dipole-dipole interaction. Chapter 1 gives a review of using solid-state NMR to obtain the structural information for biological solids. Chapter 2 introduces the theoretical background for solid-state NMR. The main thesis contains three topics. First, we show by a detailed analysis that a set of internal selection rules does exist for many basic elements of pulse sequences. And we have derived the symmetry arguments to rationalize the observation that the C-REDOR pulse sequence can suppress homonuclear dipole-dipole interaction (Chapter 3). The concept of the internal symmetry has further applied to increase the efficiency of C-REDOR (Chapter 4). Second, we design a constant-time sequence composed of DRAMA-based pulses for homonuclear dipolar dephasing (Chapter 5 and 6). Third, we introduce an approach for the dihedral angle determination of biological samples. In this part, we discuss the psi angle determination by correlation of the 13C(alpha)-1H(alpha) and the 13C(alpha)-14N dipolar tensors within a single labeled residue (Chapter 7).