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：时间分辨磁环的开发和应用 提出了二向色性光谱(TRMCD)。的应用程序 磁场产生手性，观测到的信号一般是 定位到正在被探测的吸收的那一部分。这 这项技术被用于血红素中心。将这项技术推广到 近紫外线将被开发，关于静态MCD的初步数据 色氨酸是令人鼓舞的(将需要额外的电磁铁 补偿单元窗口的法拉第旋转)。中环 想法是光解一种配体，然后研究其动力学。这个 TRMCD装置在血红素中心的分辨率约为50-100 ns 吸收(由蛋白质产生的信号使吸收部分复杂化 弥散重定向时间，大约100 ns-这个并发症已经 分析并可能是可纠正的)。细胞色素氧化酶的研究， 细胞色素C3和细胞色素C‘正在进行中。一个特别重要的问题 过去一段时间的发现是在交界处发现了短暂的结扎 细胞色素A3位点的细胞色素氧化酶，导致部分模型 结合氧还原释放能量的浇注机制 质子泵浦(配体穿梭模型)。一种未知的配体 蛋白质结合到蛋白质铁中心，这一点已经得到了最好的研究 用这种技术。未来最有趣的研究集中在 血红蛋白和R到T的变构转变，如果Trp残基可以 被隔离和测量。静态MCD显示出了一些希望 关于溶液中的色氨酸。突变体应分离出哪些色氨酸残基产生 信号。最近的TRCD结果，刚刚提交给生物化学，是 令人兴奋。优秀的研究，除了在 最后一篇综述：蛋白质取向驰豫的问题，即 在100纳秒的时间尺度上，以及生产力的问题上。