利用CαH 系统的零量子-双量子混合相干的弛豫测量研究蛋白质动力学

摘要/Abstract

摘要：

越来越多的证据说明，“传统”的弛豫测量（T₁, T₂, NOE）不足以完整描述蛋白质的复杂动态，如化学交换、构型交换或相互作用导致的动态改变. 涉及到多量子相干弛豫机制可以提供额外的动态信息. 该文测量2个蛋白质的CαH 系统的混合零量子和双量子弛豫速率随CPMG序列中脉冲间隔及温度的变化来探讨蛋白质中的动态及温度的影响. 发现2种蛋白之质中均存在可观的交换效应，且与残基位置有关. 进一步的分析表明，两位点交换模型不足以解释蛋白质的复杂动态.

关键词: 蛋白质动力学, 弛豫, 交换, 多量子相干, CPMG

Abstract:

More and more evidence indicates that the information on protein dynamics extracted from the “traditional” measurement of longitudinal, transverse and NOE cross relaxation rates is insufficient for a full description of the complex motions a protein may have, such as chemical and conformational exchanges or the interaction-induced dynamics changes. Extra dynamic information can be obtained from relaxation mechanism involving multi-quantum coherences. In this article, the effective relaxation rates of mixed zero- and double-quantum coherences of CαH systems in two proteins (one with ¹³C labeled and one natural abundant) have been measured with a modified pulse sequence. The trend of the relaxation rates with the change of the intervals between π pulses in CPMG period indicates the ubiquitous existence of exchange in the proteins. The temperature dependence of protein dynamics is shown with the measurement of effective transverse relaxation rates for three different temperatures. It is also found that the number of exchanging sites varies with type and location of the residue in a protein. Furthermore, quantitative analysis indicates that the effect of exchange on relaxation rate suggests that the presence of multi-site exchanges is common feature for proteins in solution, signifying that the exchange model currently used in description of protein exchange dynamics needs to be improved.

Key words: protein dynamics, relaxation, exchange, multi-quantum coherence, CPMG

中图分类号:

O482.53

林研诗, 方菁霞, 丁尚武. 利用CαH 系统的零量子-双量子混合相干的弛豫测量研究蛋白质动力学[J]. 波谱学杂志, 2010, 27(3): 445-460.

Yan-Shi LIN , Ching-Hsia FANG, Shang-Wu DING. Studied with the Relaxation Measurement of Mixed Zero- and Double-Quantum Coherences of CαH Systems[J]. Chinese Journal of Magnetic Resonance, 2010, 27(3): 445-460.

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