BASE TILTS IN POLYNUCLEOTIDES FROM FLOW LINEAR DICHROISM

来自流动线性二色性的多核苷酸碱基倾斜

• 批准号: 3302083
• 负责人: W C JOHNSON
• 金额: $ 10.37万
• 依托单位: OREGON STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-12-01 至 1994-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3302083
• 关键词: circular dichroism; conformation; dichroism; nuclear magnetic resonance spectroscopy; nucleic acid sequence; nucleic acid structure; nucleobase; polynucleotides; solutions; ultraviolet radiation; water solution

The overall aim of this research is to probe the conformation of polynucleotides and nucleic acids in solution, which may well be different from their conformation in crystals and fibers. Indeed, studies on the number of base pairs per turn for various DNAs indicate that this parameter is flexible, varying with sequence and certainly not the integral 10-fold repeat originally found for B-form fibers. Furthermore, a number of studies indicate that the base pairs make a fair inclination angle with the helix axis even under B-form solution conditions. Here we propose to resume our vacuum ultraviolet linear dichroism (LD) studies to determine the angle at which bases are inclined with respect to he helix axis for various base sequences and under various solution conditions. IN a flow LD experiment on helical nucleic acids with one type of basis, there are three unknowns: the inclination of the bases, the orientation of the axis around which the bases are inclined, and the coefficient for alignment of the polymer in the flow. If there is more than one kind of base in the nucleic acid, then each type of base may have a different inclination and axis. Our laboratory had developed a special flow linear dichroism instrument that will make measurements into the vacuum ultraviolet region so that the information content of the data is sufficient to solve for all of the unknowns. In previous work we determined inclination angles for some simple deoxypolynucleotides, and for DNA itself. We would now study simple ribopolynucleotides in aqueous solution, and simple deoxyribonucleotides under solution conditions that produce the A form. Furthermore, we propose to determine accurately the number of base pairs per turn for A-form DNA. We would then use the new base inclination and helix repeat data to calculate the corresponding vacuum ultraviolet CD spectra. These calculated spectra would be compared with CD spectra measured into the vacuum UV region on our special instrumentation. Furthermore, we would compare the interproton distances between the bases for these new helical repeats and base inclinations to the values obtained form NOESY data from modern 2D NMR work. Taken together, this work should be valuable for determining the true base orientation for polynucleotides and nucleic acids in solution.

本研究的总体目的是探讨 溶液中的多核苷酸和核酸，很可能是 与晶体和纤维中的构象不同。 确实，研究 各种 DNA 每转碱基对的数量表明，这 参数是灵活的，随顺序变化，当然不是 最初为 B 型纤维发现的完整 10 倍重复。 此外， 多项研究表明碱基对具有良好的倾向 即使在 B 型溶液条件下，也能与螺旋轴形成角度。 在这里我们 建议恢复我们的真空紫外线性二色性（LD）研究 确定碱基相对于螺旋的倾斜角度 各种碱基序列和各种溶液条件下的轴。 在 具有一种基础的螺旋核酸的流式 LD 实验， 存在三个未知数：底座的倾斜度、方向 底座倾斜的轴，以及系数 聚合物在流动中的排列。 如果有不止一种 核酸中的碱基，那么每种类型的碱基可能有不同的 倾角和轴。 我们实验室开发了一种特殊的流动线性 将在真空中进行测量的二色性仪器 紫外区，使得数据的信息内容为 足以解决所有未知数。 在之前的工作中我们 确定了一些简单脱氧多核苷酸的倾斜角，以及 对于DNA本身。 我们现在将研究水溶液中的简单核糖多核苷酸 溶液，以及在溶液条件下的简单脱氧核糖核苷酸 生成 A 表格。 此外，我们建议准确确定 A 型 DNA 每转的碱基对数。 然后我们将使用新的 碱基倾角和螺旋重复数据来计算相应的 真空紫外CD光谱。 将比较这些计算出的光谱 在我们的特殊设备上测量真空紫外区域的 CD 光谱 仪器仪表。 此外，我们将比较质子间距离 在这些新的螺旋重复的碱基和碱基倾斜度之间 从现代 2D NMR 工作的 NOESY 数据中获得的值。 采取 总之，这项工作对于确定真正的基础应该很有价值 溶液中多核苷酸和核酸的方向。