Helix-forming carbohydrate amino acids
Helix-forming carbohydrate amino acids
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DOI：
10.1021/jo0480040
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发表时间：
2005-03-18
影响因子：
3.6
通讯作者：
Smith, MD
中科院分区：
文献类型：
--
作者：
Claridge, TDW;Long, DD;Smith, MD
[图解]用核磁共振、红外光谱和CD研究了C-糖基-α-D-来氧呋喃构型四氢呋喃氨基酸(其中四氢呋喃环上的C-2和C-5取代基相互反式)的四聚链和八聚体在有机溶剂中的构象性质。核磁共振和红外光谱研究表明，在氯仿溶液中，四聚体7不采用氢键构象，而八聚体10填充了由16元(I，I-3)残基间氢键稳定的明确的螺旋二级结构，类似于pi-螺旋。三氟乙醇的圆二色谱研究与八聚体10的这种构象一致，也表明四聚体7采用不被氢键稳定的刚性构象。
[GRAPHICS]The solution-phase conformational properties of tetrameric and octameric chains of C-glycosyl alpha-D-lyxofuranose configured tetrahydrofuran amino acids (where the C-2 and C-5 substituents on the tetrahydrofuran ring are trans to each other) were examined using NMR and IR and CD in organic solvents. Studies by NMR and IR demonstrated that in chloroform solution, the tetramer 7 does not adopt a hydrogen-bonded conformation whereas the octamer 10 populates a well-defined helical secondary structure stabilized by 16-membered (i, i - 3) interresidue hydrogen bonds, similar to a pi-helix. Circular dichroism studies in trifluoroethanol are consistent with this conformation for the octamer 10, and also indicate that the tetramer 7 adopts a rigid conformation not stabilized by hydrogen bonds.