Spielmann H P
Department of Biochemistry, University of Kentucky, Lexington 40536-0084, USA.
Biochemistry. 1998 Apr 21;37(16):5426-38. doi: 10.1021/bi972536b.
The dynamics of the DNA oligomer d(GCGTACGC)2 and the 4'-(hydroxymethyl)-4,5',8-trimethylpsoralen-DNA furanside monoadduct (MAf) of this oligomer have been determined from NMR relaxation parameters. Longitudinal and transverse 13C relaxation rates and heteronuclear NOE relaxation data have been measured at natural abundance and have been analyzed in the context of the Lipari and Szabo model-free formalism. The generalized order parameters for methine carbons in the octamer sequence d(GCGTACGC)2 (UM) are relatively and uniformly high for the entire molecule. The generalized order parameters for methine carbons in the MAf are significantly lower for the deoxyribose bearing the damaged thymidine base and for the bases flanking the lesion on the undamaged strand, indicating additional conformational flexibility due to the lesion. The order parameters for the bases on the damaged strand flanking the lesion remain high. Analysis of the relaxation data indicates substantial chemical exchange for the adenosine residues in the UM TpA site, and this chemical exchange is quenched upon MAf formation. These data are discussed in terms of a model for DNA damage recognition by the nucleotide excision repair system.
已通过核磁共振弛豫参数确定了DNA寡聚物d(GCGTACGC)₂及其4'-(羟甲基)-4,5',8-三甲基补骨脂素-DNA呋喃糖苷单加合物(MAf)的动力学。在天然丰度下测量了纵向和横向¹³C弛豫速率以及异核NOE弛豫数据，并在Lipari和Szabo无模型形式体系的背景下进行了分析。八聚体序列d(GCGTACGC)₂（UM）中次甲基碳的广义序参数在整个分子中相对且均匀地较高。MAf中次甲基碳的广义序参数对于带有受损胸腺嘧啶碱基的脱氧核糖以及未受损链上损伤侧翼的碱基显著较低，表明损伤导致了额外的构象灵活性。损伤侧翼受损链上碱基的序参数仍然较高。弛豫数据分析表明，UM中TpA位点的腺苷残基存在大量化学交换，并且这种化学交换在MAf形成时被淬灭。根据核苷酸切除修复系统识别DNA损伤的模型对这些数据进行了讨论。
