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.

该副本是使用众多研究子项目之一 由NIH/NCRR资助的中心赠款提供的资源。子弹和 调查员（PI）可能已经从其他NIH来源获得了主要资金， 因此可以在其他清晰的条目中代表。列出的机构是 对于中心，这是调查员的机构。 大肠杆菌的天冬氨酸经钙木叶层在两个构象状态下退出，低接性性t状态和高活动性高亲和力r状态。这些酶不仅催化嘧啶生物合成途径中的第一个反应，而且还参与了整个代谢途径速率的控制。认为控制是通过改变T和R形式的比率来实现的。酶的T和R状态在功能和结构上都是不同的。在将酶从T到R状态的转化过程中，酶经历了appoxox，含量为11€的延伸，以及简单的亚基旋转，可以通过SAX轻松检测到。我们以前提出了一种从T到R状态进行一致的变构过渡的机制。我们已经能够使用时间分辨的SAX在SSRL上执行一组实验，以直接遵循从T到R状态的结构过渡的时间过程。这些初步数据表明在过渡过程中形成了结构中间体。建议在SSRL的额外光束时间继续研究酶的变构机理，以及异性效应如何影响从T到R状态的结构过渡。这将是变构酶首次实时遵循变构结构变化的时间演变。