Induction of B-A transitions of deoxyoligonucleotides by multivalent cations in dilute aqueous solution.
Induction of B-A transitions of deoxyoligonucleotides by multivalent cations in dilute aqueous solution.
复制标题
稀水溶液中多价阳离子诱导脱氧寡核苷酸的 B-A 转变。
DOI：
10.1016/s0006-3495(93)81163-9
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发表时间：
1993
影响因子：
3.4
通讯作者：
Braunlin,WH
中科院分区：
文献类型：
--
作者：
Xu,Q;Shoemaker,RK;Braunlin,WH
在Co（NH_3）_6（3+）存在下，d（CCCCGGGG）的圆二色性（CD）光谱与r（CCCCGGGG）的光谱非常相似。与此相反，B-型的特点，观察d（CCCCGGGG）在Na+和Mg 2+的存在下，即使在高盐浓度。亚精胺诱导d（CCCCGGGG）CD的适度变化。用质子二维（2D）NOESY和COSY方法对d（CCCCGGGG）在Co（NH3）6（3+）存在和不存在下的非交换质子的NMR化学位移进行了归属. d（CCCCGGGG）的GH 8质子的化学位移在用Co（NH3）6Cl 3滴定时向高场移动。糖H1'偶合常数之和随Co（NH3）6Cl 3的加入而减小。在二维质子NOESY谱中的交叉峰强度显示了添加Co（NH3）6Cl 3后从B-DNA向A-DNA特征的转变。随温度变化的59 Co横向和纵向弛豫速率表明Co（NH3）6（3+）与低聚物位点结合。这种定位不是Co（NH3）6（3+）与寡核苷酸结合的一般特征。~（59）Co核磁共振弛豫和圆二色谱（CD）测量表明Co（en）3（3+）的两种立体异构体具有d（CCCCGGGG）手性识别。这两种立体异构体结合紧密，由59钴NMR判断，都导致大（但不相等）的变化，在CD的这种低聚物。
Circular dichroism (CD) spectra of d(CCCCGGGG) in the presence of Co(NH3)6(3+) are very similar to spectra of r(CCCCGGGG). In contrast, B-form characteristics are observed for d(CCCCGGGG) in the presence of Na+ and Mg2+, even at high salt concentrations. Spermidine induces modest changes of the CD of d(CCCCGGGG). The NMR chemical shifts of the nonexchangeable protons of d(CCCCGGGG) in the absence and presence of Co(NH3)6(3+) were assigned by proton two-dimensional (2D) NOESY and COSY measurements. The chemical shifts of the GH8 protons of d(CCCCGGGG) move upfield upon titration with Co(NH3)6Cl3. The sums of the sugar H1' coupling constants decrease with added Co(NH3)6Cl3. Cross peak intensities in the 2D proton NOESY spectra show a transformation from B-DNA to A-DNA characteristics upon the addition of Co(NH3)6Cl3. The temperature-dependent 59Co transverse and longitudinal relaxation rates demonstrate that Co(NH3)6(3+) is site-bound to the oligomer. Such localization is not a general feature of Co(NH3)6(3+) binding to oligonucleotides. 59Co NMR relaxation and CD measurements demonstrate chiral discrimination by d(CCCCGGGG) for the two stereoisomers of Co(en)3(3+). Both stereoisomers bind tightly as judged by 59Co NMR, and both cause large (but nonequivalent) changes in the CD of this oligomer.