TWO-PHOTON STUDIES OF AMINO ACIDS AND NUCLEIC ACIDS

氨基酸和核酸的双光子研究

• 批准号: 2176326
• 负责人: PATRIK R CALLIS
• 金额: $ 11.86万
• 依托单位: MONTANA STATE UNIVERSITY - BOZEMAN
• 依托单位国家: 美国
• 财政年份: 1983
• 资助国家: 美国
• 起止时间: 1983-04-01 至 1994-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2176326
• 关键词: cytosine; fluorescence spectrometry; fluorescent dye /probe; indoles; molecular dynamics; nucleic acid structure; nucleobase; photoelectron spectrometry; tryptophan

The long range goals are to achieve accurate descriptions of the lower excited states of the amino acid tryptophan and of the nucleotides -- accurate in the sense that useful structural and dynamical information can be deduced from UV absorption, circular dichroism, visible two-photon absorption, and time resolved emission. This three year period focuses upon the two lowest excited states of tryptophan, 1La and 1Lb, whose relative energy is extremely sensitive to the molecular environment. Both states have been implicated as contributing to the fluorescence in recent novel experiments. The proposed work includes experiments designed to track the 1La and 1Lb states of tryptophan and model analogues in environments including the isolated and complexed molecules, various frozen solvents at liquid helium temperature, and proteins, using medium resolution (0.1 cm-1) excitation and detection to select molecules in specific sites. Two-photon excitation will figure prominently because it can distinguish 1La and 1Lb states, even in the jet-cooled beams. A strong theoretical component aims to develop semiempirical quantum methods to the level of predicting single vibronic state relative energies and to marry these with molecular mechanics and dynamics methods for predicting the effect of the molecular surroundings. An important part of this work is to test the common molecular dynamics methods which are being increasingly applied to biopolymers. The above techniques will be applied to the nucleotides, where similar theoretical difficulties exist. Computations of the effect of crystal environments will be continued because they are found to be essential in the interpretation of optical experiments on crystals of nucleic acid bases. A survey of two-photon properties of dyes being used for the new technique of two-photon laser scanning microscopy will be conducted.

远程目标是实现较低的准确描述 氨基酸色氨酸和核苷酸的激发态 - 在有用的结构和动态信息的意义上，准确的 从紫外线吸收，圆形二分色，可见的两光子中推导 吸收和时间分解的发射。 这三年的重点 在两个最低的色氨酸，1LA和1磅的激发态下 相对能量对分子环境极为敏感。 两个都 状态已被认为是造成荧光的近期 新实验。 拟议的工作包括设计为 跟踪色氨酸和模型类似物的1LA和1磅状态 包括孤立和复杂分子在内的环境，各种冷冻 使用培养基，在液氦温度和蛋白质处的溶剂 分辨率（0.1 cm-1）激发和检测以选择分子中的分子 特定站点。 两光蛋白激发将显着地发现 即使在喷射冷却梁中，也可以区分1LA和1磅状态。 强壮 理论成分旨在开发半经验量子方法 预测单振动状态相对能量并结婚的水平 这些都采用分子力学和动力学方法来预测 分子环境的影响。 这项工作的重要部分是 测试越来越多的分子动力学方法 应用于生物聚合物。 上述技术将应用于 核苷酸，存在类似的理论困难。 计算 由于发现了水晶环境的影响 在解释光学实验的晶体中至关重要 核酸碱基。 对使用的染料的两光子特性的调查 对于两光子激光扫描显微镜的新技术将是 实施。