Measurement of Hydrogen Exchange Times of the RNA Imino Protons Using by Phase-modulated CLEAN Chemical Exchange Spectroscopy

摘要

NMR hydrogen exchange experiments are the important tools for studying the conformation or dynamics of the macro-molecules.1 The imino proton resonances are good probes of the dynamic motions of the base pairs of nucleic acids. Hydrogen-deuterium exchange method is widely used to determine the exchange rates of slowly exchanging imino protons. ' The exchange rates of fast-exchanging imino protons could be measured by water magnetization transfer (WMT) method (Figure 1A). This experiment have been used to determine the exchange rates of the imino protons in DNA, RNA, DNA-protein complex, and RNA-protein complex. However, this experiment, which needs long repetition time (dl time in Figure 1) of 10 ～ 15 sec for complete relaxation of water signal, is prone to various sources of artifacts such as exchange-relayed NOE/ROE from rapidly exchanging protons in macro-molecules.