为何没有水就没有生命
文章来源:未知 文章作者:enread 发布时间:2016-06-21 08:25 字体: [ ]  进入论坛
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Scientists are getting closer to directly observing how and why water is essential to life as we know it. A study in this week's Proceedings1 of the National Academy of Sciences provides the strongest evidence yet that proteins--the large and complex molecules3 that fold into particular shapes to enable biological reactions--can't fold themselves.
 
Rather, the work of folding is done by much smaller water molecules, which surround proteins and push and pull at them to make them fold a certain way in fractions of a second, like scores of tiny origami artists folding a giant sheet of paper at blazingly fast speeds. 
 
Dongping Zhong, leader of the research group at The Ohio State University that made the discovery, called the study a "major step forward" in the understanding of water-protein interactions and said it answers a question that's been dogging research into protein dynamics4 for decades.
 
"For a long time, scientists have been trying to figure out how water interacts with proteins. This is a fundamental problem that relates to protein structure, stability, dynamics and--finally--function," said Zhong, who is the Robert Smith Professor of physics at Ohio State. 
 
"We believe we now have strong direct evidence that on ultrafast time scales (picoseconds, or trillionths of a second), water modulates5 protein fluctuations," he concluded.
 
Zhong, who is also a professor of chemistry and biochemistry, and his team used ultrafast laser pulses to take snapshots of water molecules moving around a DNA6 polymerase, the kind of protein that helps DNA reproduce. 
 
The key to getting a good view of the interaction was to precisely7 locate optical probes on the protein surface, he said. The researchers inserted molecules of the amino acid tryptophan into the protein as a probe, and measured how water moved around it.
 
Water molecules typically flow around each other at picosecond speeds, while proteins fold at nanosecond speeds--1,000 times slower. Previously8, Zhong's group demonstrated that water molecules slow down when they encounter a protein. Water molecules are still moving 100 times faster than a protein when they connect with it, however.
 
In the new study, the researchers were able to determine that the water molecules directly touched the protein's "side chains," the portions of the protein molecule2 that bind9 and unbind with each other to enable folding and function. The researchers were also able to note the timing10 of movement in the molecules.


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1 proceedings Wk2zvX     
n.进程,过程,议程;诉讼(程序);公报
参考例句:
  • He was released on bail pending committal proceedings. 他交保获释正在候审。
  • to initiate legal proceedings against sb 对某人提起诉讼
2 molecule Y6Tzn     
n.分子,克分子
参考例句:
  • A molecule of water is made up of two atoms of hygrogen and one atom of oxygen.一个水分子是由P妈?f婘??妈?成的。
  • This gives us the structural formula of the molecule.这种方式给出了分子的结构式。
3 molecules 187c25e49d45ad10b2f266c1fa7a8d49     
分子( molecule的名词复数 )
参考例句:
  • The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
  • Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里,大分子裂变为小分子。
4 dynamics NuSzQq     
n.力学,动力学,动力,原动力;动态
参考例句:
  • In order to succeed,you must master complicated knowledge of dynamics.要取得胜利,你必须掌握很复杂的动力学知识。
  • Dynamics is a discipline that cannot be mastered without extensive practice.动力学是一门不做大量习题就不能掌握的学科。
5 modulates a88c456a9b7801726f99dc163ab3230f     
调整( modulate的第三人称单数 ); (对波幅、频率的)调制; 转调; 调整或改变(嗓音)的音调
参考例句:
  • At this point the music modulates from C to G. 在此处音乐从C调转到G调。
  • Modulates the level of adrenaline to relieve stress and fatigue. 剌激肾上腺素的分泌,有助纾缓压力、消除疲劳。
6 DNA 4u3z1l     
(缩)deoxyribonucleic acid 脱氧核糖核酸
参考例句:
  • DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
  • Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。
7 precisely zlWzUb     
adv.恰好,正好,精确地,细致地
参考例句:
  • It's precisely that sort of slick sales-talk that I mistrust.我不相信的正是那种油腔滑调的推销宣传。
  • The man adjusted very precisely.那个人调得很准。
8 previously bkzzzC     
adv.以前,先前(地)
参考例句:
  • The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
  • Let me digress for a moment and explain what had happened previously.让我岔开一会儿,解释原先发生了什么。
9 bind Vt8zi     
vt.捆,包扎;装订;约束;使凝固;vi.变硬
参考例句:
  • I will let the waiter bind up the parcel for you.我让服务生帮你把包裹包起来。
  • He wants a shirt that does not bind him.他要一件不使他觉得过紧的衬衫。
10 timing rgUzGC     
n.时间安排,时间选择
参考例句:
  • The timing of the meeting is not convenient.会议的时间安排不合适。
  • The timing of our statement is very opportune.我们发表声明选择的时机很恰当。
TAG标签: water life molecules
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