Temperature dependence of proton-proton residual dipolar couplings in adenosine dissolved in charged phospholipid bicelles. Application of a two-dimensional selective refocusing method

摘要

H-1 NMR spectra of nucleoside adenosine were recorded in 7.5% (w/v) DMPC/DHPC bicelles doped with CTAB. Despite the small size of adenosine in comparison with the distances between discoidal bicelles, intramolecular H-1,H-1 residual dipolar couplings D were observed at 29.5-38degreesC. The absolute values of H-1,H-1 spin interactions Delta (sum of J- and D-couplings) were measured selectively by a series of 2D SERF experiments as a function of temperature. At lower temperatures dipolar couplings are scaled down, which leads to simplification of the H-1 NMR spectra. For some pairs of protons, which are simultaneously J- and D-coupled, the exact values of D can be determined from temperature dependence of Delta. Copyright (C) 2002 John Wiley Sons, Ltd. [References: 20]