经济学人下载:分子生物学 蛋白质的奥秘(2)

One of the leading researchers in the field of protein folding is David Baker of the University of Washington, in Seattle.
西雅图华盛顿大学的David Baker是蛋白质折叠领域研究者的领军人物之一。

For the past 20 years he and his colleagues have used increasingly sophisticated versions of a program they call Rosetta to generate various possible shapes for a given protein, and then work out which is most stable and thus most likely to be the real one.
在过去的20年中，他的团队应利用越来越复杂的“Rosetta”程序，模拟出给定蛋白质的各种可能结构，然后研究对比哪一种结构最稳定并最接近于真正的蛋白质结构。

In 2015 they predicted the structures of representative members of 58 of the missing protein families.
2015年他们预测了58个未知蛋白质家族成员的代表结构。

Last month they followed that up by predicting 614 more.
就在1月份他们已预测出614多种蛋白质结构。

Even a small protein can fold up into tens of thousands of shapes that are more or less stable.
仅仅一个小的蛋白质也能折叠出数以千计的较为稳定的结构。

According to Dr Baker, a chain a mere 70 amino acids long—a tiddler in biological terms—has to be folded virtually inside a computer about 100,000 times in order to cover all the possibilities and thus find the optimum.
Baker博士表示，一条仅70个氨基酸长度的链，在生物界如同一个小孩儿，而想要找到所有的可能性并确定最佳结构需要在电脑中虚拟折叠近10万次。

Since it takes a standard microprocessor ten minutes to do the computations needed for a single one of these virtual foldings, even for a protein this small, the project has, for more than a decade, relied on cadging processing power from thousands of privately owned PCs.
由于完成仅一个如此小的蛋白质的虚拟折叠便需标准微处理器计算耗时10分钟，故这个项目在十多年来一直借助于上千台个人电脑的处理能力。

Volunteers download a version of Dr Baker’s program, called rosetta@home, that runs in the background when a computer is otherwise idle.
志愿者可以下载rosetta@home，这是Baker博士的程序，当电脑闲置时可让其在后台运行。

This “citizen science” has helped a lot.
“全民科研”的作用很大。

But the real breakthrough, which led to those 672 novel structures, is a shortcut known as protein-contact prediction.
但真正的突破性进展是一个被称为蛋白质-接触预测的捷径，使得科学家发现了672个新的蛋白质结构。

This relies on the observation that chain-folding patterns seen in nature bring certain pairs of amino acids close together predictably enough for the fact to be used in the virtual-folding process.
这得益于在链-折叠模式的自然状态下，观察到了特定的氨基酸对会被拉近在一起的现象，其可预测性足以用于虚拟折叠进程。

An amino acid has four arms, each connected to a central carbon atom.
一个氨基酸有4条支链，每支连接一个中心碳原子。

Two arms are the amine group and the acid group that give the molecule its name.
其中有2条支链是用于分子命名的胺基和酸根。

Protein chains form because amine groups and acid groups like to react together and link up.
蛋白质会互相连接是因为胺基遇到酸根，易反应并连接在一起。

The third is a single hydrogen atom.
第3条支链只有一个氢原子。

But the fourth can be any combination of atoms able to bond with the central carbon atom.
任何能和中心碳原子相连的任意原子组合，都能与第四条支链相连接。

It is this fourth arm, called the side chain, which gives each type of amino acid its individual characteristics.
这第4条支链叫做侧链，赋予每种类型的氨基酸各自的性质。