Nuclear magnetic resonance (NMR) spectroscopy of lipid A is limited by rapid transversal relaxation and subsequent line broadening caused by the tendency of these glycolipids to form aggregates in all solvents. To examine the influence of solvents on NMR spectra, hexa-acyl lipid A from Escherichia coli F515 was investigated. Line widths at half height, longitudinal relaxation times, and transversal relaxation times were measured in different solvents, lipid A concentrations, and temperatures. Chloroform-d, dioxane-d(8), and pyridine-d(5) each mixed with 25% methanol-d(4) as well as sole DMSO-d(6) and 0.1M triethylamine-d(15) (TEA-d(15)) in D(2)O caused good spectral resolutions and allowed structure analysis. ROESY and HMBC spectra gave an insight into the influence of transversal relaxation times on spectral quality in two-dimensional spectra. Solvent depending differences of interglycosidic NOEs indicated dissimilarities of the conformations in the interglycosidic linkage and allowed conclusions about the lipid A solution state.

中文翻译：

---

脂质A的核磁共振-溶剂对自旋弛豫和光谱质量的影响。

脂质A的核磁共振（NMR）光谱受到快速横向松弛和随后的谱线展宽的限制，这些谱线展宽是由这些糖脂在所有溶剂中形成聚集体的趋势引起的。为了检查溶剂对NMR谱的影响，研究了来自大肠杆菌F515的六酰基脂质A。在不同的溶剂，脂质A浓度和温度下测量了半高处的线宽，纵向弛豫时间和横向弛豫时间。氯仿-d，二恶烷-d（8）和吡啶-d（5）分别与25％甲醇-d（4）以及唯一的DMSO-d（6）和0.1M三乙胺-d（15）（TEA）混合D（2）O中的-d（15））引起了良好的光谱分辨率并允许进行结构分析。ROESY和HMBC光谱深入分析了横向弛豫时间对二维光谱中光谱质量的影响。