Bornet O, Prévost C, Vovelle F, Chassignol M, Thuong N T, Lancelot G
Centre de Biophysique Moléculaire, CNRS, Orléans, France.
Nucleic Acids Res. 1995 Mar 11;23(5):788-95. doi: 10.1093/nar/23.5.788.
Psoralen (pso) was attached via its C-5 position to the 5'-phosphate group of an oligodeoxynucleotide d(TAAGCCG) by a hexamethylene linker (m6). Complex formation between pso-m6-d(TAAGCCG) and the complementary strands d(CGGCTTA)[7-7mer] or d(CGGCTTAT)[7-8mer] was investigated by nuclear magnetic resonance in aqueous solution. Structural informations derived from DQF-COSY and NOESY maps, revealed that the mini double helix adopts a B-form conformation and that the deoxyriboses preferentially adopt a C2'-endo conformation. The nOe connectivities observed between the protons of the bases or the sugars in each duplex, and the protons of the psoralen and the hexamethylene chain, led us to propose a model involving an equilibrium between two conformations due to different locations of the psoralen. Upon UV-irradiation, the psoralen moiety cross-linked the two DNA strands at the level of 5'TpA3' sequences. NMR studies of the single major photo-cross-linked duplex pso-m6-d(TAAGCCG) and d(CGGCTTA) were performed. The stereochemistry of the diadduct is indeed cis-syn at both cyclobutane rings. In addition, the effects of this diadduct on the helical structure are analyzed in detail.
补骨脂素(pso)通过其C-5位经由一个六亚甲基连接体(m6)连接到寡聚脱氧核苷酸d(TAAGCCG)的5'-磷酸基团上。通过水溶液中的核磁共振研究了pso-m6-d(TAAGCCG)与互补链d(CGGCTTA)[7-7聚体]或d(CGGCTTAT)[7-8聚体]之间的复合物形成。从双量子滤波相关谱(DQF-COSY)和核Overhauser效应谱(NOESY)图谱获得的结构信息表明,迷你双螺旋采用B型构象,且脱氧核糖优先采用C2'-内型构象。在每个双链体中观察到的碱基或糖的质子与补骨脂素和六亚甲基链的质子之间的核Overhauser效应(nOe)连接性,使我们提出一个模型,该模型涉及由于补骨脂素的不同位置而在两种构象之间存在平衡。经紫外线照射后,补骨脂素部分在5'TpA3'序列水平交联两条DNA链。对单一主要光交联双链体pso-m6-d(TAAGCCG)和d(CGGCTTA)进行了核磁共振研究。在两个环丁烷环处,双加合物的立体化学确实为顺式-顺式。此外,还详细分析了该双加合物对螺旋结构的影响。