酶性甲基转移:活性位点残留物在产生活性位点缩中的作用与催化效率相关
Jianyu Zhang1, Judith P Klinman
1Department of Chemistry, University of California, Berkeley, California 94720, USA.
Journal of the American Chemical Society
|October 1, 2011
概括
人类甲基转移酶 (COMT) 酶的活性与活性部位的紧缩有关. 突变显示了催化效率和动态同位素效应之间的相关性,影响了多巴胺代谢.
科学领域:
- 生物化学 生物化学
- 酶学 是一种酶学.
- 分子生物学分子生物学
背景情况:
- 人类catechol-O-methyltransferase (COMT) 对于多巴胺代谢至关重要,它催化了从S-adenosylmethionine (AdoMet) 中的甲基转移.
- 了解COMT的催化机制和遗传变异的影响对于神经科学和药理学至关重要.
研究的目的:
- 为了研究活体位结构和人类COMT中的催化效率之间的关系.
- 为了表征特定位点突变和COMT的Val108Met多态变体.
- 探索活性位点紧缩在酶功能的作用和潜在的气道化.
主要方法:
- 人类COMT在Tyr68,Trp38和Val108位置的局部定向突变发生.
- 酶动力学测试以确定催化效率 (kcat/Km) 和产品分布.
- 测量二次动态同位素效应 (SKIEs) 以探测过渡状态动态.
主要成果:
- Tyr68和Val108Met变异的突变显示了催化效率和SKIE大小之间的线性相关性.
- 这些发现表明,在AdoMet结合位点附近的残留物影响下,活性位点的紧缩会调节COMT的催化性能.
- 结果提供了实验证据,支持活点压缩在酶催化反应中的作用.
结论:
- 活性位点紧缩是COMT功能中的关键调节机制,受特定氨基酸残留的影响.
- 观察到的催化效率和SKIE之间的相关性为甲基转移反应的过渡状态提供了洞察力.
- 这些发现有助于对酶机制的理解,特别是在活性位点动态和气道现象方面.
更多相关视频
10:20In vitro Digestion of Emulsions in a Single Droplet via Multi Subphase Exchange of Simulated Gastrointestinal Fluids
Published on: November 18, 2022
10:23Characterizing Mediated Extracellular Electron Transfer in Lactic Acid Bacteria with a Three-Electrode, Two-Chamber Bioelectrochemical System
Published on: August 23, 2024
相关概念视频
Induced-fit Model
Most chemical reactions in cells require enzymes—biological catalysts that speed up the reaction without being consumed or permanently changed. They reduce the activation energy needed to convert the reactants into products. Enzymes are proteins, that usually work by binding to a substrate—a reactant molecule that they act upon.
Enzymes exhibit substrate specificity, meaning that they can only bind to certain substrates. This is mainly determined by the shape and chemical characteristics of...
Enzymes exhibit substrate specificity, meaning that they can only bind to certain substrates. This is mainly determined by the shape and chemical characteristics of...
Enzymes
Inside living organisms, enzymes act as catalysts for many biochemical reactions involved in cellular metabolism. The role of enzymes is to reduce the activation energies of biochemical reactions by forming complexes with its substrates. The lowering of activation energies favor an increase in the rates of biochemical reactions.
Enzyme deficiencies can often translate into life-threatening diseases. For example, a genetic abnormality resulting in the deficiency of the enzyme G6PD...
Enzyme deficiencies can often translate into life-threatening diseases. For example, a genetic abnormality resulting in the deficiency of the enzyme G6PD...
Mechanical Protein Functions
Proteins perform many mechanical functions in a cell. These proteins can be classified into two general categories- proteins that generate mechanical forces and proteins that are subjected to mechanical forces. Proteins providing mechanical support to the structure of the cell, such as keratin, are subjected to mechanical force, whereas proteins involved in cell movement and transport of molecules across cell membranes, such as an ion pump, are examples of generating mechanical force.
Enzymes and Activation Energy
The activation energy (or free energy of activation), abbreviated as Ea, is the small amount of energy input necessary for all chemical reactions to occur. During chemical reactions, certain chemical bonds break, and new ones form. For example, when a glucose molecule breaks down, bonds between the molecule's carbon atoms break. Since these are energy-storing bonds, they release energy when broken. However, the molecule must be somewhat contorted to get into a state that allows the bonds to...
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...
Amino Acid Catabolism
Microorganisms rely on proteins as an essential carbon and energy source, particularly in environments with limited polysaccharides or lipids. However, proteins are too large to cross the plasma membrane unaided, necessitating enzymatic degradation. Microbes secrete extracellular proteases and peptidases that hydrolyze proteins into peptides, which can then be transported across the membrane. Once inside the cell, intracellular proteases degrade these peptides into free amino acids, which...
