在Escherichia coli二酸二酸减少酶的催化性受损变体中增加了动态效应
J Javier Ruiz-Pernia1, Louis Y P Luk, Rafael García-Meseguer
1Departament de Química Física i Analítica, Universitat Jaume I , 12071 Castello, Spain.
Journal of the American Chemical Society
|November 21, 2013
概括
突变的二叶酸还原酶 (DHFR) 中的同位素替代表明,在五秒时间尺度上的灵活性增加,而不是毫秒运动,阻碍了催化. 这表明,与化学步骤的动态合可能会损害酶活性.
科学领域:
- 生物化学 生物化学
- 酶动力学 酶动力学
- 蛋白质动力学 蛋白质动力学
背景情况:
- 大肠杆菌二叶酸减少酶 (EcDHFR) 的突变可能会损害催化活性.
- 了解蛋白质动态在酶催化中的作用对于酶工程至关重要.
研究的目的:
- 研究同位素替代和突变对EcDHFR的催化机制的影响.
- 阐明活性部位动态与催化物的化学步骤之间的关系.
主要方法:
- 一种具有催化性损害的 EcDHFR 变体 (EcDHFR-N23PP/S148A) 的同位素替代 ((15) N, (13) C, (2) H).
- 对准经典的自由能障碍和过渡状态动态的分析.
- 活动部位运动的时间分辨率测量.
主要成果:
- 催化速率常数的降低主要是由于增加的自由能量屏障,次要是增加的轨迹重交.
- 变种酶需要更大的活性部位重组才能达到过渡状态.
- 毫秒运动的损失被增加的五秒灵活性所补偿,这对催化有害.
结论:
- 触媒性受损的EcDHFR变体在化学步骤中表现出"动态敲进",其中增加的动态合会损害催化.
- 这一发现对理解 EcDHFR 和其他酶系统中的转移有意义.
- 在不同的时间尺度上酶活性部位的灵活性在催化效率中起着至关重要的作用.
相关概念视频
Stringent Response in E. coli
533
Bacterial growth is closely tied to nutrient availability, with cells proliferating exponentially under favorable conditions and entering a stationary phase when resources become scarce. This transition is mediated by a regulatory mechanism known as the stringent response, which allows bacteria to adapt to nutrient deprivation by modulating gene expression and metabolic activity.During nutrient scarcity, intracellular amino acid levels decline. It results in the accumulation of uncharged tRNAs...
533
Pharmacogenetics of Drug Targets: β₂-Adrenergic Receptors, Apo E, Thymidylate Synthase
84
Genetic polymorphisms in drug targets have emerged as critical determinants of interindividual variability in drug response and toxicity. Pharmacogenomic investigations increasingly focus on identifying these variations to personalize and optimize therapeutic interventions. A drug target may be a receptor, enzyme, or signaling protein involved in pharmacologic responses or disease-related pathways. While early pharmacogenetic studies focused primarily on drug metabolism, current research...
84
Bacterial Gastroenteritis
92
Bacterial gastroenteritis, characterized by diarrhea, abdominal cramps, and vomiting, is often caused by ingestion of contaminated food or water and is frequently associated with pathogenic Escherichia coli strains. These microbes exploit two principal mechanisms to inflict disease.Shiga toxin–producing E. coli, also referred to as STEC—notably O157:H7—release Shiga toxins that target ribosomes, blocking protein synthesis. The B subunit of the toxin binds the host glycolipid...
92
The Electron Transport Chain
13.8K
The electron transport chain or oxidative phosphorylation is an exothermic process in which free energy released during electron transfer reactions is coupled to ATP synthesis. This process is a significant source of energy in aerobic cells, and therefore inhibitors of the electron transport chain can be detrimental to the cell's metabolic processes.
Inhibitors of the electron transport chain
Rotenone, a widely used pesticide, prevents electron transfer from Fe-S cluster to ubiquinone or Q...
Inhibitors of the electron transport chain
Rotenone, a widely used pesticide, prevents electron transfer from Fe-S cluster to ubiquinone or Q...
13.8K


