控制基质进入甲单氧基酶活性部位的控制
Seung Jae Lee1, Michael S McCormick, Stephen J Lippard
1Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Nature
|February 12, 2013
概括
甲营养菌是一种消耗甲的细菌,甲是一种温室气体. 这项研究揭示了调控蛋白 (MMOB) 如何控制可溶性甲单氧化酶 (MMO) 酶.
科学领域:
- 生物化学 生物化学
- 微生物学 微生物学
- 结构生物学 结构生物学
背景情况:
- 甲营养生物通过消耗甲,一种强大的温室气体,在全球碳循环中发挥着至关重要的作用.
- 溶性甲单氧酶 (sMMO) 是负责甲氧化,将其转化为甲醇的酶.
- 由于结构数据有限,调控蛋白MMOB在小MMO活动中的确切功能尚不清楚.
研究的目的:
- 阐明sMMO的基酶 (MMOH) 和调节蛋白 (MMOB) 组成部分之间的原子级相互作用.
- 了解MMOB如何调节MMOH的催化活性,特别是对活性部位的基板访问.
主要方法:
- 使用X射线晶体学来确定MMOH-MMOB (H-B) 复合物的结构.
- 结构分析的重点是MMOB和MMOH基酶子单元之间的接口.
主要成果:
- 晶体结构显示,MMOB在MMOH复合体的α(2) 2) 2) 接口上停靠.
- MMOB结合会诱导MMOHα子单元的构造变化,控制甲和氧气进入二铁活性部位.
- 这些形状变化对于将酶的活性指向甲氧化而不是NADH氧化至关重要.
结论:
- 该结构为SMMO的监管机制提供了MMOB的第一个原子级洞察力.
- MMOB作为一个关键的守门员,通过精确控制基质进入活性站点来确保高效的甲氧化.
- 这项研究说明了大型蛋白质复合体如何通过复杂的调节机制实现特定的生物催化.
相关概念视频
01:19Regulation of Metabolism
Cellular needs and conditions vary from cell to cell and change within individual cells over time. For example, the required enzymes and energetic demands of stomach cells are different from those of fat storage cells, skin cells, blood cells, and nerve cells. Furthermore, a digestive cell works much harder to process and break down nutrients during the time that closely follows a meal compared with many hours after a meal. As these cellular demands and conditions vary, so do the amounts and...
01:12Mechanically-gated Ion Channels
Mechanically-gated ion channels are proteins found in eukaryotic and prokaryotic cell membranes that open in response to mechanical stress. Tension, compression, swelling, and shear stress can alter the conformation of the protein, opening a transmembrane channel that allows the passage of ions for signal transmission. In eukaryotes, mechanically-gated channels are distributed in several regions like the neurons, lungs, skin, bladder, and heart, where they play critical roles in numerous...
01:12Mechanically-gated Ion Channels
Mechanically-gated ion channels are proteins found in eukaryotic and prokaryotic cell membranes that open in response to mechanical stress. Tension, compression, swelling, and shear stress can alter the conformation of the protein, opening a transmembrane channel that allows the passage of ions for signal transmission. In eukaryotes, mechanically-gated channels are distributed in several regions like the neurons, lungs, skin, bladder, and heart, where they play critical roles in numerous...
01:24Metal-Semiconductor Junctions
The contact of metal and semiconductor can lead to the formation of a junction with either Schottky or Ohmic behavior.
Schottky Barriers
Schottky barriers arise when a metal with a work function (Φm) contacts a semiconductor with a different work function (Φs). Initially, electrons transfer until the Fermi levels of the metal and semiconductor align at equilibrium. For instance, if Φm > Φs, the semiconductor Fermi level is higher than the metal's before contact. The semiconductor's...
Schottky Barriers
Schottky barriers arise when a metal with a work function (Φm) contacts a semiconductor with a different work function (Φs). Initially, electrons transfer until the Fermi levels of the metal and semiconductor align at equilibrium. For instance, if Φm > Φs, the semiconductor Fermi level is higher than the metal's before contact. The semiconductor's...
01:16MOSFET
The Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) plays a pivotal role in modern electronics thanks to its versatility and efficiency in controlling electrical currents. This device, also known as IGFET, MISFET, and MOSFET, has three main terminals: the Source, Drain, and Gate. MOSFETs are classified into n-channel or p-channel types based on the doping characteristics of their substrate and the source or drain regions.
In an n-MOSFET, the structure includes n-type source and drain...
In an n-MOSFET, the structure includes n-type source and drain...
01:22MOSFET: Enhancement Mode
Enhancement-mode MOSFETs are pivotal components in electronics, distinguished by their capacity to act as highly efficient switches. They are part of the larger family of metal-oxide Semiconductor Field-Effect Transistors (MOSFETs). They are available in two types: p-channel and n-channel, each tailored to specific polarity operations.
In their basic form, enhancement-mode MOSFETs are typically non-conductive when the gate-source voltage (Vgs) is zero. This default 'off' state means no current...
In their basic form, enhancement-mode MOSFETs are typically non-conductive when the gate-source voltage (Vgs) is zero. This default 'off' state means no current...