Freedberg Darón I
Laboratory of Biophysics, CBER/FDA, 29 Lincoln Drive, Building 29 HFM-419, Bethesda, Maryland 20892, USA.
J Am Chem Soc. 2002 Mar 13;124(10):2358-62. doi: 10.1021/ja010981v.
A simple solution NMR method is presented for pucker determination of five-membered rings using only residual dipolar couplings obtained in a single liquid crystalline medium, DMPC/DHPC bicelles (DMPC = dimyristoylphosphatidylcholine; DHPC = dihexanoylphosphatidylcholine). The method was applied to determine the pucker of the fructofuranosyl ring of sucrose. The results indicate a fructofuranosyl pucker phase in the 20 degrees - 70 degrees range. The pucker phases are in agreement with those from previous NMR and optical spectroscopic studies and, importantly, do not rely on empirically parametrized Karplus curves. Furthermore, the analysis implies more than one stable pucker phase and rapid ring interconversion in this range. The present results suggest that using residual dipolar couplings alone can reveal multiple conformations present in solution. Hence, when a sufficient number of residual dipolar coupling constants is measured, the outcome is a robust, reliable, and independent route for determining carbohydrate and nucleic acid structure by NMR spectroscopy.
本文提出了一种简单的溶液核磁共振（NMR）方法，用于仅使用在单一液晶介质二肉豆蔻酰磷脂酰胆碱/二己酰磷脂酰胆碱双分子层（DMPC = 二肉豆蔻酰磷脂酰胆碱；DHPC = 二己酰磷脂酰胆碱）中获得的剩余偶极耦合来确定五元环的折叠情况。该方法被应用于确定蔗糖中呋喃果糖环的折叠情况。结果表明，呋喃果糖环的折叠相在20°至70°范围内。这些折叠相与先前的核磁共振和光谱研究结果一致，重要的是，不依赖于经验参数化的卡普拉斯曲线。此外，分析表明在该范围内存在不止一种稳定的折叠相且环快速相互转化。目前的结果表明，仅使用剩余偶极耦合就可以揭示溶液中存在的多种构象。因此，当测量足够数量的剩余偶极耦合常数时，这是一种通过核磁共振光谱确定碳水化合物和核酸结构的稳健、可靠且独立的途径。
