NUCLEIC ACID ELECTROSTATIC PROPERTIES FROM CRYSTALS

晶体核酸的静电特性

• 批准号: 3296555
• 负责人: BRYAN M CRAVEN
• 金额: $ 13.6万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-03-01 至 1993-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3296555
• 关键词: X ray crystallography; chemical models; crystallization; electron density; hydrogen bond; mathematical model; neutron diffraction; nucleic acid structure; oligonucleotides

Electrostatic properties of the nucleic acids will be determined from X-ray and neutron single crystal diffraction studies of simple nucleic acid components ranging up to minihelical dinucleotide structures. Emphasis will be on mapping the electrostatic potential, either within the crystal unit cell, or for molecules extracted from the crystal lattice. We have shown that the electrostatic potential can be experimentally determined more easily than other molecular properties such as the charge density or the electric field. With a simple structure model including only a monopole atomic charge parameters in addition to the atomic parameters used in conventional crystal structure determinations, we expect to obtain physically meaningful maps of electrostatic potential for molecules containing at least 50 atoms. Such results will be of particular significance for the nucleic acids which have strongly ionic character and contain many polar groups. The H bonding of the bases, their stacking, the binding of counterions and polar molecules such as water, all involve interactions which are predominantly electrostatic. We will map the electrostatic potential in the voids of nucleotide crystal structures after water molecules and cations are completely or selectively removed from the pseudoatom model, and in this way we will study their binding sites. An important characteristic of this project is that experimental electrostatic potentials will be carefully crosschecked for consistency with each other and with results from simple benchmark crystal structures. Atomic charges which are shown to give a satisfactory molecular electrostatic potential will then be candidates for inclusion as parameters in the semi-empirical force-fields required for molecular mechanics calculations. Such calculations are being used increasingly in studies of nucleic acid structure and dynamics.

将确定核酸的静电性能 来自X射线和中子单晶体衍射研究 简单的核酸成分，达到迷你核酸 二核苷酸结构。 重点是映射 静电电势，无论是在晶体单位电池内还是用于 从晶格中提取的分子。 我们已经表明 静电电势可以实验确定 比其他分子特性（例如电荷）更容易 密度或电场。 使用简单的结构模型 另外仅包括单极原子电荷参数 到常规晶体结构中使用的原子参数 确定，我们希望获得物理有意义的地图 至少50个分子的静电电位 原子。 这种结果对于核酸特别重要 具有强烈的离子特征，并且包含许多极性 组。 基地的H键合，它们的堆叠，结合 柜台和极地分子（例如水）都涉及 主要是静电的相互作用。 我们将映射 核苷酸晶体空隙中的静电电势 水分子和阳离子后的结构完全或 有选择地从pseudoatom模型中删除，并以此方式删除 我们将研究它们的约束位点。 该项目的一个重要特征是实验 静电电势将仔细检查 彼此保持一致性，并与简单的结果 基准晶体结构。 所示的原子费 那么，要具有令人满意的分子静电电势 候选人作为半经验中的参数纳入参数 分子力学计算所需的力场。 这样的 计算越来越多地用于核酸的研究 结构和动态。