合素步骤到ATP水解的合
W Hua1, E C Young, M L Fleming
1Biophysics and Structural Biology Graduate Program, Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02254, USA.
Nature
|July 24, 1997
概括
研究人员量化了动力运动的动力运动,发现一个ATP分子在微管沿着8nm步骤提供动力. 这种1ATP到8nm的合在各种ATP度中是一致的,澄清了kinesin.
科学领域:
- 生物化学 生物化学
- 分子生物学分子生物学
- 细胞生物学 细胞生物学
背景情况:
- 像kinesin这样的ATP驱动的运动蛋白对于细胞内运输至关重要.
- 了解素的精确机械步骤和能量合对于阐明其功能至关重要.
- 之前的研究报告了素的不同步骤大小 (5-8纳米),分析因布朗运动和快速ATP周转而复杂化.
研究的目的:
- 为了准确量化由单个ATP分子驱动的素运动的步骤大小.
- 为了解决ATP水解和kinesin的机械位移之间的关系.
- 为了确定观察到的合在不同的ATP度中是否一致.
主要方法:
- 使用先进的光显微镜,具有超低的位置漂移 (<39 pms[-1]).
- 观察到单个素分子在非常低的ATP度 (150nM) 中缓慢移动,以分离时间事件.
- 应用了基于统计的分析方法,将未解决的运动计算在内,以确定步骤大小和ATP合.
主要成果:
- 素表现出一种基本的酶循环,其中单个ATP水解事件与8.12纳米的步骤距离相结合,匹配微管原细丝网格间距.
- 排除了其他步距离的移动和复杂的ATP-to-step合比率 (例如,每步2个ATP).
- 在广泛的ATP度范围内,ATP消耗率与步进率的比率保持不变.
结论:
- 素的基本步骤大小为8nm,直接与一个ATP分子的水解相结合.
- 这种1 ATP:8 nm合机制是素酶循环的一般特征,适用于低度至高度的ATP.
- 这些发现提供了清晰的定量理解基因素在分子水平上的机械功能.
相关概念视频
01:08Hydrolysis of ATP
The bonds of adenosine triphosphate (ATP) can be broken through the addition of water, releasing one or two phosphate groups in an exergonic process called hydrolysis. This reaction liberates the energy in the bonds for use in the cell—for instance, to synthesize proteins from amino acids.
If one phosphate group is removed, a molecule of ADP—adenosine diphosphate—remains, along with inorganic phosphate. ADP can be further hydrolyzed to AMP—adenosine monophosphate—by the removal of a second...
If one phosphate group is removed, a molecule of ADP—adenosine diphosphate—remains, along with inorganic phosphate. ADP can be further hydrolyzed to AMP—adenosine monophosphate—by the removal of a second...
01:32Chemiosmosis
Oxidative phosphorylation is a highly efficient process that generates large amounts of adenosine triphosphate (ATP), the basic unit of energy that drives many cellular processes. Oxidative phosphorylation involves two processes— the electron transport chain and chemiosmosis.
Electron Transport Chain
The electron transport chain involves a series of protein complexes on the inner mitochondrial membrane that undergo a series of redox reactions. At the end of this chain, the electrons reduce...
Electron Transport Chain
The electron transport chain involves a series of protein complexes on the inner mitochondrial membrane that undergo a series of redox reactions. At the end of this chain, the electrons reduce...
01:08Hydrolysis of ATP
The bonds of adenosine triphosphate (ATP) can be broken through the addition of water, releasing one or two phosphate groups in an exergonic process called hydrolysis. This reaction liberates the energy in the bonds for use in the cell—for instance, to synthesize proteins from amino acids.
If one phosphate group is removed, a molecule of ADP—adenosine diphosphate—remains, along with inorganic phosphate. ADP can be further hydrolyzed to AMP—adenosine monophosphate—by the removal of a second...
If one phosphate group is removed, a molecule of ADP—adenosine diphosphate—remains, along with inorganic phosphate. ADP can be further hydrolyzed to AMP—adenosine monophosphate—by the removal of a second...
01:48ATP Synthase: Mechanism
In animals, the mitochondrial F1F0 ATP synthase is the key protein that synthesizes ATP molecules through a complex catalytic mechanism. While the nuclear genome encodes the majority of ATP synthase subunits, the mitochondrial genome encodes some of the enzyme's most critical components. The formation of this multi-subunit enzyme is a complex multi-step process regulated at the level of transcription, translation, and assembly. Defects in one or more of these steps can result in decreased ATP...
01:31ATP Energy Storage and Release
ATP is a highly unstable molecule. Unless quickly used to perform work, ATP spontaneously dissociates into ADP and inorganic phosphate (Pi), and the free energy released during this process is lost as heat. The energy released by ATP hydrolysis is used to perform work inside the cell and depends on a strategy called energy coupling. Cells couple the exergonic reaction of ATP hydrolysis with endergonic reactions, allowing them to proceed.
One example of energy coupling using ATP involves a...
One example of energy coupling using ATP involves a...
01:31ATP Energy Storage and Release
ATP is a highly unstable molecule. Unless quickly used to perform work, ATP spontaneously dissociates into ADP and inorganic phosphate (Pi), and the free energy released during this process is lost as heat. The energy released by ATP hydrolysis is used to perform work inside the cell and depends on a strategy called energy coupling. Cells couple the exergonic reaction of ATP hydrolysis with endergonic reactions, allowing them to proceed.
One example of energy coupling using ATP involves a...
One example of energy coupling using ATP involves a...