TIME EVOLUTION OF THE ALLOSTERIC TRANSITION OF ASPARTATE TRANSCARBAMOYLASE

天冬氨酸转氨甲酰酶变构转变的时间演化

• 批准号: 7597962
• 负责人: EVAN R KANTROWITZ
• 金额: $ 0.3万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-03-01 至 2008-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7597962
• 关键词: Affinity; Anabolism; Aspartate; Carbamoyl Transferases; Computer Retrieval of Information on Scientific Projects Database; Data; Enzymes; Escherichia coli; Evolution; Funding; Grant; Institution; Investigation; Metabolic Pathway; Molecular Conformation; Pathway interactions; Pyrimidine; Pyrimidines; Rate; Reaction; Research; Research Personnel; Resources; Rotation; Source; Thinking; Time; United States National Institutes of Health; enzyme mechanism; research study; time use

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Aspartate transcarbamoylase from E. coli exits in two conformational states, a low-activity low-affinity T state and a high-activity high-affinity R state. The enzyme not only catalyzes the first reaction in the pyrimidine biosynthesis pathway, but is also involved in the control of the rate of this entire metabolic pathway. Control is thought to be achieved by altering the ratio of the T and R forms. The T and R states of the enzyme are both functionally and structurally distinct. During the conversion of the enzyme from the T to the R state, the enzyme undergoes an elongation of appoximately 11 ¿, along with simultaneous rotations of subunits, which can easily be detected by SAXS. We have previously proposed a mechanism for a concerted allosteric transition from the T to the R states. We have been able to perform one set of experiments at SSRL using time-resolved SAXS to directly follow the time course of the structural transition from the T to the R state. These preliminary data suggest that a structural intermediate is formed during the transition. This proposal is for additional beam time at SSRL to continue the investigation into the allosteric mechanism of the enzyme and how the heterotropic effects influence the structural transition from the T to the R state. This will be the first time for an allosteric enzyme that the time evolution of the allosteric structural change will be followed in real time by SAXS.

该子项目是利用该技术的众多研究子项目之一 资源由 NIH/NCRR 资助的中心拨款提供。 研究者 (PI) 可能已从 NIH 的另一个来源获得主要资金， 因此可以出现在其他 CRISP 条目中 列出的机构是。 对于中心来说，它不一定是研究者的机构。 来自大肠杆菌的天冬氨酸转氨甲酰酶以两种构象状态存在，即低活性低亲和力T态和高活性高亲和力R态。该酶不仅催化嘧啶生物合成途径中的第一个反应，而且还参与其中。控制整个代谢途径的速率被认为是通过改变酶的 T 和 R 状态的比例来实现的。结构上不同。在酶从 T 态转变为 R 态的过程中，酶经历了大约 11 ¿ ，以及亚基的同时旋转，这可以很容易地被 SAXS 检测到。我们之前提出了一种从 T 状态到 R 状态的协调变构转变的机制，我们已经能够在 SSRL 上使用 time- 进行一组实验。解析 SAXS 直接跟踪从 T 状态到 R 状态的结构转变的时间过程。这些初步数据表明，在转变过程中形成了结构中间体。该提议是为了在 SSRL 上增加光束时间，以继续对变构的研究。该酶的机制以及异向效应如何影响从 T 状态到 R 状态的结构转变 这将是变构酶首次通过 SAXS 实时跟踪变构结构变化的时间演变。