COMPARE 39K TRANSVERSE RELAXATION IN VITRO SOLUTIONS & IN CYTOPLASM OF E COLI

比较 39K 横向松弛体外解决方案

• 批准号: 6298205
• 负责人: M. THOMAS RECORD
• 金额: $ 0.75万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-03-01 至 2000-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6298205
• 关键词: biological products; biomaterials; biomedical resource; nuclear magnetic resonance spectroscopy; nucleic acids; proteins

The most abundant cation and osmolyte in the cytoplasm of E. coli, K+, has been used in studies of molecular interactions of DNA, proteins, ribosome and ions via 39K NMR. In our previous experiments, a large transverse relaxation rate of 39K has been observed in dense slurries of E. coli cells. Since the interaction of the K nucleus with the surrounding electric field gradient of the DNA dominants the 39K transverse relaxation in a K-DNA solution with little salt added, it was considered as the explanation for the 39K relaxation measured in vivo. However, the relaxation rate of 39K in DNA solutions, even with a very high concentration (i.e., physiological conditions), is much slower than that in vivo. Similar results were obtained for concentrated K-BSA and KCl solutions. The only in vitro solution that gives rise to the same large magnitude of the transverse relaxation rate as in vivo are ribosome solutions, the highly negative charged ribosome particles that have the most nucleic acids in the cell. Therefore, ribosome particles are considered as the key element that enhances the transverse relaxation of 39K in vivo. The similar characteristic of transverse relaxation was also observed in 23Na-ribosome solutions. These results require further experimental studies to confirm and to explore the molecular nature of the ribosome particle and K+, Na+-ribosome interactions. We will be using the DMX 400 spectrometer with the 10mm BB probe for both 39K and 23Na (a more sensitive nucleus) NMR studies.

大肠杆菌细胞质中最丰富的阳离子和渗透剂， K+，已用于 DNA 分子相互作用的研究， 通过 39K NMR 检测蛋白质、核糖体和离子。 在我们之前的实验中， 在致密材料中观察到 39K 的大横向弛豫率 大肠杆菌细胞浆液。 由于K核相互作用 DNA 周围的电场梯度占主导地位 添加少量盐的 K-DNA 溶液中的 39K 横向弛豫， 这被认为是对测量到的 39K 弛豫的解释 体内。 然而，DNA 溶液中 39K 的弛豫率，即使 具有非常高的浓度（即生理条件），是 比体内慢很多。 获得了类似的结果 浓 K-BSA 和 KCl 溶液。 唯一的体外解决方案 产生相同幅度的横向弛豫 速率与体内核糖体溶液一样，带高负电荷 细胞中含有最多核酸的核糖体颗粒。 因此，核糖体颗粒被认为是 增强体内39K的横向弛豫。 类似的 还观察到横向弛豫特征 23Na-核糖体溶液。 这些结果还需要进一步的实验 确认和探索核糖体分子性质的研究 粒子与K+、Na+-核糖体相互作用。 我们将使用DMX 400 光谱仪，配有 10mm BB 探头，适用于 39K 和 23Na（更多 敏感核）核磁共振研究。