溶剂对大肠杆菌二酸盐减少酶的催化作用
E Joel Loveridge1, Lai-Hock Tey, Rudolf K Allemann
1School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK.
Journal of the American Chemical Society
|January 6, 2010
概括
反应介质的介电常数,而不是粘度,会影响由二叶酸减少酶 (DHFR) 催化化物转移的速率. 溶剂的变化没有影响动态同位素效应或其温度依赖.
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:
- 二叶酸减少酶 (DHFR) 通过环境合道化催化化物转移.
- 蛋白质运动被认为可以控制基质/辅因子结合,并调节激活屏障宽度,从而影响反应速率.
- 反应介质组成的变化会扰乱蛋白质的运动.
研究的目的:
- 研究反应介质组成对DHFR催化化物转移动学的影响.
- 为了确定介电常数或介质粘度是否影响酶催化.
- 探索溶剂特性与化物转移机制之间的关系.
主要方法:
- 在各种辅溶剂和辅溶剂的存在下测量了大肠杆菌DHFR的动力参数.
- 分析了动态同位素效应及其温度依赖性.
- 结果与Thermotoga maritima.之前对DHFR的研究结果进行了比较.
主要成果:
- 反应介质的介电常数显著影响了反应速率,而粘度没有.
- 无论是主要的动态同位素效应还是其温度依赖性都没有受到散装溶剂特性的影响.
- 溶剂对大肠杆菌DHFR动态同位素效应的温度依赖的影响对现有模型提出了挑战.
结论:
- 通过DHFR的酶催化对周围介质的介电特性敏感.
- 这些发现表明,虽然远程运动可能不是唯一的决定因素,但近距离振动或形状子状态可能在DHFR催化中发挥作用.
- 需要进一步的研究,以充分阐明溶剂对DHFR催化化物转移的影响机制.
更多相关视频
12:08Catalytic Reactions at Amine-Stabilized and Ligand-Free Platinum Nanoparticles Supported on Titania During Hydrogenation of Alkenes and Aldehydes
Published on: June 24, 2022
12:08Monitoring the Reductive and Oxidative Half-Reactions of a Flavin-Dependent Monooxygenase using Stopped-Flow Spectrophotometry
Published on: March 18, 2012
相关概念视频
Heterogeneous Catalysis
Heterogeneous catalysis involves a catalyst in a different phase from the reactants. It is a process where the catalyst and the reactants are in distinct phases, typically solid and gas or liquid.Most heterogeneous catalysts are metals, metal oxides, or acids. The list includes transition metals like iron (Fe), cobalt (Co), nickel (Ni), palladium (Pd), platinum (Pt), chromium (Cr), manganese (Mn), tungsten (W), silver (Ag), and copper (Cu). These metals possess partially vacant d orbitals that...
Solvating Effects
An understanding of the solvating effect helps rationalize the relation between solvation and acidity of the compound. In addition, this also explains the relative stability of conjugate bases for compounds with different pKa values. This lesson details, in-depth, the principle of solvating effects. The strength of an acid and the stability of its corresponding conjugate base are determined using pKa values. This observed relationship is a consequence of solvation, which is the interaction...
Catalysis
The presence of a catalyst affects the rate of a chemical reaction. A catalyst is a substance that can increase the reaction rate without being consumed during the process. A basic comprehension of a catalysts’ role during chemical reactions can be understood from the concept of reaction mechanisms and energy diagrams.
Catalysis
Catalysis influences the rate of chemical reactions by providing an alternative reaction pathway with lower activation energy. A catalyst speeds up a reaction, but it is not consumed during the process. The fundamental principle of catalysis is the ability of a catalyst to alter the reaction mechanism, often introducing a more efficient pathway than the uncatalyzed process.In a catalyzed reaction, the catalyst participates directly in the reaction mechanism. It interacts with reactants to form...
Leveling Effect
In acid-base chemistry, the leveling effect refers to the limitation imposed by the solvent on the strength of acids and bases in solution. When a base stronger than the solvent's conjugate base is used, it deprotonates the solvent until the base is entirely consumed, making it ineffective against weaker acids. Conversely, an acid stronger than the solvent's conjugate acid protonates the solvent until the acid is depleted, rendering it ineffective against weaker bases. Essentially, the solvent...
Introduction to Mechanisms of Enzyme Catalysis
For many years, scientists thought that enzyme-substrate binding took place in a simple "lock-and-key" fashion. This model stated that the enzyme and substrate fit together perfectly in one instantaneous step. However, current research supports a more refined view scientists call induced fit. The induced-fit model expands upon the lock-and-key model by describing a more dynamic interaction between enzyme and substrate. As the enzyme and substrate come together, their interaction causes a mild...
