TIME-RESOLVED MAGNETIC CIRCULAR DICHROISM

时间分辨磁圆二色性

• 批准号: 2900657
• 负责人: DAVID S. KLIGER
• 金额: $ 18.05万
• 依托单位: UNIVERSITY OF CALIFORNIA SANTA CRUZ
• 依托单位国家: 美国
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-07-01 至 2000-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2900657
• 关键词: biomedical equipment development; chemical kinetics; circular magnetic dichroism; conformation; cytochrome b; cytochrome c; cytochrome oxidase; electron transport; enzyme mechanism; enzyme structure; hemoglobin; hemoprotein structure; magnetic field; method development; molecular dynamics; mutant; photochemistry; photolysis; protein structure function; structural biology; time resolved data; ultraviolet radiation

DESCRIPTION: Development and use of time resolved magnetic circular dichroism spectroscopy (TRMCD) is proposed. The application of a magnetic field induces chirality and the observed signal is generally localized to the moiety who's absorption is being probed. This technique is used for heme centers. Extension of the technique to the near UV is to be developed, and preliminary data on the static MCD of tryptophan is encouraging (will require an extra electromagnet to compensate for the Faraday rotation of the cell windows). The central idea is to photolyze a ligand and then study the kinetics. The resolution of the TRMCD apparatus is about 50-100 ns in the heme center absorption (partly complicated by signals that result from the protein diffusional reorientation time, about 100 ns- this complication has been analyzed and is probably correctable). Studies on cytochrome oxidase, cytochrome c3, and cytochrome c' are ongoing. A particularly important finding of the past period was the finding of a transient ligation at the cytochrome a3 site of cytochrome oxidase, resulting in a model for part of the gating mechanism coupling energy release by oxygen reduction to proton pumping (the ligand shuttle model). An unknown ligand in the protein binds to the protein iron center and this has been best studied with this technique. Most interesting future studies center on hemoglobin and the R to T allosteric transition, if the trp residues can be isolated and measured. Some hope has been demonstrated by static MCD on trp in solution. Mutants should isolate which trp residues yield signal. Recent TRCD results, just submitted to Biochemistry, are exciting. Outstanding studies except there were two problems cited in last review: the problem of protein orientational relaxation, which is on the 100 ns time scale, and the issue of productivity.

描述：时间解析磁循环的开发和使用 提出了二分色谱法（TRMCD）。 应用 磁场诱导手性，观察到的信号通常为 正在探测与吸收的部分的本地化。 这 技术用于血红素中心。将技术扩展到 将要开发紫外线附近，并在静态MCD上进行初步数据 色氨酸令人鼓舞（将需要额外的电磁体 补偿单元窗的法拉第旋转）。 中央 想法是将配体照相，然后研究动力学。 这 TRMCD设备的分辨率约为血红素中心的50-100 ns 吸收（部分由蛋白质引起的信号复杂化 扩散重新定位时间，大约100 ns-这种并发症已经 分析，可能是可更正的）。 研究细胞色素氧化酶， 细胞色素C3和细胞色素c'正在进行中。 一个特别重要的 在过去的发现是发现在 细胞色素A3的细胞色素氧化酶，导致部分模型 通过还原氧的门控机理耦合能量释放 质子抽水（配体班车型号）。一个未知的配体 蛋白质与蛋白质铁中心结合，最好对此进行研究 使用这种技术。 最有趣的未来研究中心 如果TRP残基可以 被隔离并测量。静态MCD证明了一些希望 在解决方案中的TRP上。突变体应隔离哪些TRP残基产生 信号。刚刚提交生物化学的最近的TRCD结果是 令人兴奋。杰出的研究除了在 上次评论：蛋白质定向放松的问题，即 在100 ns的时间范围内以及生产力问题。