JEFFERSON SHARED CIRCULAR DICHROISM FACILITY

蛋白质和核酸的圆二色性对二级和三级结构的变化反应强烈，并允许未知结构的初始分配。根据分光计的灵敏度，圆二色性光谱可以在一微克或更少的样品上测量。因此，圆二色光谱允许研究配体与蛋白质和核酸的结合，以及蛋白质/核酸的相互作用，在生理浓度下，使用微克量的纯化样品。类似地，模型结构可能在分析的早期就被分配给未知的大分子，在获得足够数量的纯样品用于核磁共振光谱或X射线晶体学之前。基于这些能力，灵敏、现代、可靠的圆二色谱仪构成了确定蛋白质和核酸结构和功能的重要资源。杰弗逊中心的核心用户组建议用一台现代的、计算机控制的Jasco J-715分光偏振仪取代PI在RR01554下获得的不可靠的、已有15年历史的Jasco J-500分光偏振仪。所提出的新光谱仪可以可靠地测量到165 nm，而不是大约200 nm，具有显着更高的信噪比。多个样品的珀尔梯温度控制将允许+/-0.2度的温度精度，与单个样品的循环水浴控制在+/-2.0度相比。现代计算机接口将允许多次扫描，波长精度为+/-0.2 nm，而不是+/-2.0 nm。结构分析包可以方便地分析光谱和反褶积到结构组件中。有了现代光谱仪，核心用户将能够更快地阐明以下问题。1. 嵌合DNA和PNA衍生物的主干如何通过dGGGG基序控制四聚体的形成？2. 转座子Tn7蛋白如何识别正确的DNA转座位点？3. 不寻常的核酸修饰如何改变新型c-erbB-2反义疗法的结构和性质？4. 肿瘤蛋白TCL-1和MTCP-1的失活突变会改变它们的结构吗？5. 蛋白聚糖在结合时如何重组胶原蛋白？6. 锌指蛋白如何识别特定的RNA靶标？7. 在癌症、艾滋病毒感染和免疫疾病中活跃的受体的小肽拮抗剂是否采用模仿其来源的结构域结构的结构？

The circular dichroism of proteins and nucleic acids responds strongly to changes in secondary and tertiary structure, and allows initial assignment of unknown structures. Circular dichroic spectra may be measured on a microgram of sample, or less, depending on the sensitivity of the spectrometer. As a result, circular dichroic spectra permit the study of ligand binding to proteins and nucleic acids, and of protein/nucleic acid interactions, at physiological concentrations, using microgram quantities of purified samples. Similarly, model structures may be assigned to unknown macromolecules early in their analysis, before sufficient amounts of pure sample have been obtained for NMR spectroscopy or X- ray crystallography. Based on these capabilities, a sensitive, modern, and reliable circular dichroism spectrometer comprises a vital resource for determining the structure and function of proteins and nucleic acids. The core group of users at Jefferson proposes to replace the unreliable 15-year-old Jasco J-500 spectropolarimeter acquired by the PI under RR01554 with a modern, computer-controlled Jasco J-715 spectropolarimeter. The proposed new spectrometer can measure reliably down to 165 nm, rather than approximately 200 nm, with significantly greater signal-to-noise ratio. Peltier temperature control of multiple samples will allow temperature precision of +/-0.2 degrees, compared with circulating water bath control of single samples at +/-2.0 degrees. A modern computer interface will allow multiple scanning with wavelength precision of +/-0.2 nm, rather than +/-2.0 nm. A structural analysis package will permit facile analysis of spectra and deconvolution into structural components. With a modern spectrometer, the core users will be able to elucidate more rapidly the following questions. 1. How does the backbone of chimeric DNA and PNA derivatives control tetraplex formation by dGGGG motifs? 2. How do transposon Tn7 proteins recognize correct DNA sites for transposition? 3. How do unusual nucleic acid modifications alter the structure and properties of novel c-erbB-2 antisense therapeutics? 4. Do inactivating mutations in oncoproteins TCL-1 and MTCP-1 alter their structures? 5. How do proteoglycans reorganize collagen upon binding? 6. How do zinc finger proteins recognize specific RNA targets? 7. Do small peptide antagonists of receptors active in cancer, HIV infection and immunological diseases adopt structures mimicking the structures of the domains from which they were derived?