C8-AMINO PURINE NUCLEOSIDES - WELL-DEFINED STERIC DETERMINANT OF GLYCOSYL CONFORMATIONAL PREFERENCES
C8-AMINO PURINE NUCLEOSIDES - WELL-DEFINED STERIC DETERMINANT OF GLYCOSYL CONFORMATIONAL PREFERENCES
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DOI：
10.1016/0005-2787(77)90290-8
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发表时间：
1977-01-01
期刊：
影响因子：
--
通讯作者：
NIV, H
中科院分区：
文献类型：
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作者：
JORDAN, F;NIV, H
对腺苷和鸟苷及其8-NH2、8-NHCH3、8-N(CH3)2和8-溴衍生物的稀溶液进行PMR测量。核糖C2”-H的化学位移，特别是C1”-H和C2”-H共振之间化学位移的差异，清楚地表明核苷是以糖基构象（c8 -二甲氨基衍生物）存在，还是以灵活的syn-anti混合物（单甲基氨基和氨基衍生物）存在。这些指标的温度依赖行为可以用来定义顺反平衡随温度的质的变化。增加的C1“-H- c2”-H化学位移分离意味着向更多的反构象转移，减少的分离意味着向更多的同步构象转移。
PMR measurements were performed on dilute solutions of adenosine and guanosine and their 8-NH2, 8-NHCH3, 8-N(CH3)2 and 8-bromo derivatives. The chemical shift of the ribose C2''-H and especially the difference in chemical shifts between the C1''-H and C2''-H resonances clearly indicate whether the nucleoside exists in a syn glycosyl conformation (the C8-dimethylamino derivatives) or as a flexible syn-anti mixture (the monomethylamino and amino derivatives). The temperature dependent behavior of these indicators can be employed to define qualitative shifts in syn-anti equilibrium with temperature. An increased C1''-H-C2''-H chemical shift separation implies shift to more anti, a decreased separation a shift to more syn conformers.