OPTICAL PROPERTIES OF BIOLOGICAL MACROMOLECULES

这个项目的总体目标是改进 分析和拓宽光学光谱学的应用，特别是 圆二色谱(CD)，用于蛋白质和核酸的研究。 近年来，人们对CD的兴趣大增。 由于它在监测蛋白质折叠方面的价值，在次要的 蛋白质的结构分析，在表征突变蛋白质时，在 在DNA和RNA的构象转变之后，在测量 蛋白质-蛋白质和蛋白质-核酸的平衡和动力学。在.期间 未来五年，该项目将集中在四个主要领域：(1) 蛋白质的本征CD，即主链和侧链的贡献；(2) 蛋白质与配体相互作用产生的外在CD； 核酸碱基的电子结构和Cd 寡核苷酸；(4)参与蛋白质的实验研究 转录及其调控。在第一个领域，基本的 用于计算多肽CD的理论模型为 扩展到包括高能跃迁、静电场效应和 多肽间电荷转移。DeVoe的扩展版本或 经典极化率模型将得到更广泛的应用，以提供 更令人满意的带状。计算以下项目的供款 将进行特定的芳香族侧链，并将结果进行比较 那些来自定点突变的基因。CD-分子联合动力学 (MD)计算将对模型多肽和小分子 蛋白质。关于第二个区域，亚铁血红素的CD跃迁 将对许多高分辨率X射线衍生结构进行计算 蛋白质，以及一氧化碳氧合肌球蛋白血红素异构体的分子动力学轨迹。 我们解释静电场对电子结构影响的工作 核酸碱基的范围将扩大到核苷酸和碱基对。 此外，其核磁共振结构的寡核苷酸的CD 将测定结果进行计算，并与实验结果进行比较。这个 真核生物大亚基C-末端结构域的构象 RNA聚合酶II，由一长串重复序列组成 七肽，将被研究。人类I型Tax蛋白 白血病病毒及其与碱性亮氨酸拉链蛋白的相互作用 以及碱性螺旋-环-螺旋蛋白，将通过CD和 荧光。

The overall objective of this project is to improve the methods of analysis and broaden the applications of optical spectroscopy, especially circular dichroism (CD), to the study of proteins and nucleic acids. There has been a major resurgence of interest in CD in recent years because of its value in monitoring protein folding, in secondary structural analysis of proteins, in characterizing mutant proteins, in following conformational transitions in DNA and RNA, and in measuring protein-protein and protein-nucleic acid equilibria and kinetics. During the next five years, the project will concentrate on four major areas: (1) intrinsic CD of proteins, i.e. backbone and side-chain contributions; (2) extrinsic CD of proteins due to protein-ligand interactions; (3) electronic structure of the nucleic acid bases and the CD of oligonucleotides; (4) experimental studies of proteins involved in transcription and its regulation. In the first area, the basic theoretical model used in calculating the CD of polypeptides will be extended to include high-energy transitions, static-field effects, and interpeptide charge transfer. The extended version of the DeVoe or classical polarizability model will be applied more extensively to provide more satisfactory band shapes. Calculations of the contributions of specific aromatic side chains will be performed and the results compared to those from site-directed mutagenesis. Combined CD-molecular dynamics (MD) calculations will be performed on model polypeptides and small proteins. With respect to the second area, the CD of heme transitions will be calculated for high-resolution X-ray-derived structures of many proteins, and for MD trajectories for carbonmonoxymyoglobin heme isomers. Our work on interpreting static-field effects on the electronic structure of the nucleic acid bases will be extended to nucleotides and base pairs. In addition, the CD of oligonucleotides for which NMR structures have been determined will be calculated and compared with experiment. The conformation of the C-terminal domain of the large subunit of eukaryotic RNA polymerase II, which consists of a long sequence of a repeating heptapeptides, will be investigated. The Tax protein of human type I leukemia virus and its interactions with basic-leucine zipper proteins, as well as basic helix-loop-helix proteins, will be studied by CD and fluorescence.