Weimar T, Meyer B, Peters T
Institute for Biophysical Chemistry, University of Frankfurt, Germany.
J Biomol NMR. 1993 Jul;3(4):399-414. doi: 10.1007/BF00176007.
One-dimensional transient NOE build-up curves were measured for the synthetic disaccharide alpha-D-Fuc-(1-->4)-beta-D-GlcNAc 1 utilizing Gaussian shaped pulses. Simulated build-up curves from Metropolis Monte Carlo simulations were compared to the experimental data. Disaccharide 1 is structurally related to methyl beta-D-maltoside in that it also contains an alpha-(1-->4) linkage, and it has the same configuration of groups around the glycosidic linkage. Analysis of NOEs in methyl beta-D-maltoside is restricted to those observed upon selective excitation of H1' because of severe spectral overlap. The situation is different in 1 where 1H-NMR signals are well separated. Several interglycosidic NOEs were observed. The corresponding build-up curves allowed an accurate determination of the conformational preferences at the glycosidic linkage in 1. Comparison of experimental and theoretical NOE build-up curves showed clearly that rigid minimum-energy models cannot account for the experimental data. The best fit of experimental NOE build-up curves was obtained with theoretical curves from a 2 x 10(6) step Metropolis Monte Carlo simulation with the temperature parameter set at 1000 K. Finally, it was observed that only the interglycosidic NOE H5'/H6-pro-S significantly depends upon varying conformation distributions at the alpha-(1-->4)-glycosidic linkage, induced by choosing different temperature parameters for the Metropolis Monte Carlo simulations.
利用高斯形状脉冲测量了合成二糖α-D-岩藻糖基-(1→4)-β-D-乙酰氨基葡萄糖1的一维瞬态NOE积累曲线。将来自 metropolis 蒙特卡罗模拟的模拟积累曲线与实验数据进行了比较。二糖1在结构上与β-D-麦芽糖甲基酯相关，因为它也含有α-(1→4)键，并且在糖苷键周围具有相同的基团构型。由于严重的光谱重叠，β-D-麦芽糖甲基酯中NOE的分析仅限于在选择性激发H1'时观察到的那些。在二糖1中情况不同，其1H-NMR信号分离良好。观察到了几个糖苷间的NOE。相应的积累曲线允许准确确定二糖1中糖苷键处的构象偏好。实验和理论NOE积累曲线的比较清楚地表明，刚性最低能量模型不能解释实验数据。通过 metropolis 蒙特卡罗模拟的2×10(6)步理论曲线，将温度参数设置为1000K，获得了实验NOE积累曲线的最佳拟合。最后，观察到只有糖苷间的NOE H5'/H6-pro-S显著依赖于通过为 metropolis 蒙特卡罗模拟选择不同温度参数而在α-(1→4)-糖苷键处诱导的不同构象分布。
