BECKMAN XL-1 ANALYTICAL ULTRACENTRIFUGE

我们建议获得一个国家的最先进的贝克曼优化（Tm）XL-I分析超吸收光谱仪配备了吸光度和瑞利干涉光学。马萨诸塞州大学目前还没有E型或类似的分析型超声波仪。研究者小组由八名NIH资助的研究者组成;七名用户来自伍斯特的马萨诸塞州医学中心大学，代表三个不同的学术部门。第八个研究者位于附近的阿默斯特马萨诸塞州大学校园。对于九个主要用户来说，获得XL-I分析超级离心机对于实现其NIH资助的研究计划的目标是必要的。所有用户都从事生物大分子的定量研究，他们为分子结构的研究带来了广泛的背景和兴趣。由于大分子的结构和行为会随着浓度、溶液成分、pH值和温度的变化而显著变化，因此在相似的溶液条件下测定不同的性质往往是必要的。通过分析超离心法的分析唯一地满足了这一要求。主要用户正在研究的领域是1）酵母组蛋白八聚体和SWI/SNF染色质重塑复合物的组装，2）动力蛋白和动力蛋白亚基的性质，3）协同血红蛋白的组装，4）RecA细丝组装，5）G蛋白和交换因子的核苷酸依赖性相互作用，6）副粘病毒膜融合，7）肌肉收缩的结构和调节，8）染色质三维结构分析。累积起来，这九个研究提案涵盖了整个范围的问题，其中分析超离心是理想的适合回答，包括测量样品纯度，检测和表征的构象变化，确定亚基化学计量，并表征组装和拆卸机制的超分子组件。拟议的仪器采购将满足马萨诸塞州大学NIH支持的研究人员的迫切研究需求。

We propose to acquire a state-of-the-art Beckman Optimal (Tm) XL-I analytical ultracentrifuge equipped with both absorbance and Rayleigh interference optics. No Model E or comparable analytical ultracentrifuge is currently available at the University of Massachusetts. The investigator group is composed of eight NIH-funded investigators; seven users are from the University of Massachusetts Medical Center at Worcester and represent three different academic departments. The eighth investigator is located at the nearby University of Massachusetts campus at Amherst Acquisition of a XL-I analytical ultracentrifuge has become necessary for the nine major users to accomplish aims of their NIH-funded research programs. All of the users are engaged in quantitative studies of biological macromolecules and they bring a broad spectrum of backgrounds and interests to the investigation of molecular structure. Because macromolecular structure and behavior Can vary markedly with concentration, solution components, pH, and temperature, it is often essential that different properties be determined under similar solution conditions. Analyses by analytical ultracentrifugation uniquely fulfills this requirement. Areas under investigation by the major users are 1) assembly of yeast histone octamers and the SWI/SNF chromatin remodeling complex, 2) properties of dynamin and dynein subunits, 3) assembly of cooperative Hemoglobins, 4) RecA filament assembly, 5) Nucleotide dependent interactions of G proteins and exchange factors, 6) Paramyxovirus membrane fusion, 7) Structure and regulation of muscle contraction, and 8) analysis of the 3-D structure of chromatin. Cumulatively, these nine research proposals cover the entire range of questions for which the analytical ultracentrifuge is ideally suited to answer, including measurements of sample purity, detection and characterization of conformational changes, determination of subunit stoichiometries, and characterization of assembly and disassembly mechanisms for supramolecular assemblies. The proposed instrument purchase will fulfill acute research needs of NIH-supported investigators at the University of Massachusetts.