BECKMAN XL-1 ANALYTICAL ULTRACENTRIFUGE

我们建议购买最先进的贝克曼最优（Tm） XL-I分析超离心机，配备吸光度和瑞利干涉光学。目前在马萨诸塞大学没有E型或类似的分析型超离心机。研究小组由8名美国国立卫生研究院资助的研究人员组成；7名用户来自伍斯特的马萨诸塞大学医学中心，分别代表三个不同的学术部门。第八位研究者位于马萨诸塞大学附近的阿默斯特校区，为了完成nih资助的研究项目，九位主要用户必须购买一台XL-I分析超离心机。所有的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、溶液组分、pH值和温度的变化而显著变化，因此在相似的溶液条件下确定不同的性质往往是必要的。分析性超离心分析独特地满足了这一要求。主要用户研究的领域是1)酵母组蛋白八聚体和SWI/SNF染色质重塑复合体的组装，2)动力蛋白和动力蛋白亚基的性质，3)合作血红蛋白的组装，4)RecA丝的组装，5)G蛋白和交换因子的核苷酸依赖相互作用，6)副粘病毒膜融合，7)肌肉收缩的结构和调节，8)染色质的三维结构分析。累积起来，这九个研究提案涵盖了分析性超离心机非常适合回答的所有问题，包括样品纯度的测量，构象变化的检测和表征，亚基化学计量学的测定，以及超分子组装和拆卸机制的表征。拟议的仪器购买将满足美国国立卫生研究院支持的马萨诸塞大学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.