【摘要】 最近通过核磁共振、很动光谱和分子力学模拟研究表明，在溶液中三螺旋DNA的构象具有一定程度的复杂性和多样性．本文首次采用近红外付立叶拉曼光谱研究了三螺旋DNAdA10·2d10。和相应的双螺旋DNAdA10·dT10在溶液中的构象．结果表明该三螺旋DNA同时存在C3’－内褶／反对称（A－型）和C2’－内褶／反对称（B－型）两种构象，而且在823cm－1处的较强谱带暗示还存在一种处于A和B构型之间的中间构型．对出现在1218cm-1和638cm-1处、归属于对糖环构象敏感的胸腺嘧啶残基的两个特征谱带进行分析，获得了除C2’－内褶构象外其它构型存在的证据．另外，双螺旋DNA的FT－Raman光谱表明该双螺旋DNA在溶液中以A－和B－两种构型共存．更多还原

【Abstract】 Recent structural investigations of triple helices by NMR, vibration spectroscopy and molecular modelling suggest that their conformation in solution conain sugars with more than one type of puder. In this paper, the conformation of triple helices dA10·2dT10 and duplex dA10·dT10 have been investigated by near infrared Fouxier transform Raman spectroscopy at excited wavelength 1064nm. In the case of triplex DNA,FT-Raman spectra obtained clearly reveal the ealstence of both C3’-endo/anti (A-type)and C2’-endo/anti (B-type), moreover, a relatively intensive band at 823cm-1 suggests the existence of an intermediate conformation between C2’-endo/anti and C3’-endo/anti sugar puckers. The analysis of the characteristic bands at around 1218cm-1 and 638cm-1 of thymine residues that are sensitive to sugar puders gives evidences for the existence of a significant displacement from the C2’-endo confomer. Ih the case of duplex DNA dA10·dT10, FT-Raman spectra obtained show the existence of both A-like and B-like conformations in the solution.更多还原