Right now, trillions of chemical reactions are humming away in the cells of your body.
现在，你身体的细胞里正在嗡嗡地发生着数万亿次的化学反应。
You never feel them, but without these reactions, you wouldn't be alive.
你从不会感觉到，但没有这些反应，你就没有办法生存。
Unfortunately, each of those reactions needs some help.
不幸的是，每个反应都需要一些帮助。
You see, most molecules are stable, they are happy just the way they are.
你看，大部分的分子都是稳定的，它们非常享受现在的状态。
The atoms in them are all bound-up and friendly with one another and would prefer to stay that way.
分子里的原子都紧密友好地相互围绕，而且都更喜欢这样的方式。
The problem is, for a chemical reaction to happen,
问题是，为了让一个化学反应发生，
the atoms that make up those stable molecules need to break away from their friends and go buddy up with another atom.
分子里原本处于稳定状态的原子就需要和它们的伙伴分开，去巴结其他的原子。
This break-up is where the molecules need a hand.
如何让原子们分手，就是分子们需要帮忙的关键点。
This initial kick-start is known as activation energy.
活化能被视为初始的动力。
It's used to destabilize the molecule,
它被用来让分子失去稳定，
to push the bonds between the atoms to a place where they are ready to break.
打破原子间的结合键，去到需要它们的地方。
This unstable state is known as the molecule's transition state.
这种不稳定的状态就是分子的过渡态。
Once a transition state has been achieved,
一旦达到过渡态，
the atoms become willing to leave their current molecular friends and go make new friends elsewhere.
原子们就会愿意离开他们现在的分子朋友，到其他地方交新朋友。
Once they are convinced, it's a piece of cake.
一旦它们被说服，事情就简单啦。
Bonds break, atoms rearrange, and the rest of the reaction happens automatically.
结合键被打破，原子重新组合，剩下的反应就理所当然地发生了。
After that first push, the body doesn't need to put in any more energy to help the reaction along.
一旦推了这一把，身体就不需要再动用其他的能量帮助进行反应。
Left alone, most of these reactions would be very slow
不受打扰的话，大多数的反应都是很慢的，
because it takes quite a while to build up the activation energy the molecules need to get started.
因为它需要一些时间来生成活化能，让分子完成重组。

Enter the enzyme. Enzymes are proteins that speed up, or catalyze, reactions by lowering the activation energy.
让我们来认识一下酶。酶是一种蛋白质，它可以通过通过降低活化能，让反应加速或者是催化反应。
They make it easier for the molecule, also known as a substrate, to get to the transition state.
这时的分子就是基质，能够让分子更加容易地达到过渡态。
You can think of a reaction like a race.
你可以把一次反应想象成一场比赛。
Some racers are running along, while others have teammates to help them.
一些参赛者是自己跑，而其他的参赛者有队友帮助他们。
Meet Sam the Substrate. His team is the MODS Squad.
让我们来看看基质Sam。它的团队是MODS小组。
Together, his team is able to get to the finish faster, using less energy.
聚在一起，它的团队就能够让比赛结束得更快，而且消耗的能量更少。
There are four special enzymes in Sam's team.
在Sam的团队里有四种特殊的酶。
Each has a different strategy for lowering the energy it takes to get going and speeding up the pace to get the MODS to the finish line.
为了让耗能降低，每一个都有自己的策略，并且想办法让团队能够加速到达终点线。
The "M" stands for "microenvironment".
“M”表示“微环境”。
This enzyme creates a tiny, special environment for the substrate, resulting in a faster reaction time.
酶会为基质创造一个微小的、特殊的环境，这能够让反应时间加快。
He runs ahead of the pack, flattening out bumps in the road and misting cool water on his team of molecules.
它就能够在被清理平坦的路上顺利前进，而且整个分子团队还有冰水照顾。
"O" is for "orientation". Sometimes two molecules must be positioned just right before they will react.
“O”是“定位”。有些时候两个分子在反应之前必须被定位。
Like a friend at the finish line, the O enzyme provides his molecules with specially shaped spaces
就像是一个朋友在终点线，O酶就为它的分子提供特殊形状的空间，
that allow the substrates to interact in just the right way.
就能让基质们以正确的方式相互作用。
"D" stands for "direct participation".
“D”表示“直接参与”。
Every now and again, a little muscle is needed.
每一个时刻都几乎不需要肌肉参与。
And when his teammates are struggling to finish the race,
当它的队友们都在向着比赛的终点挣扎的时候，
Teammate D is there to pick them up and carry them over the line.
队友D就搭上它们，直接把它们搬到终点线。
Finally, "S" is for "straining bonds".
最后，“S”表示“拉扯结合键”。
This guy pushes the team through some serious flexibility exercises: splits, lunges, backbends, the works.
这家伙强迫整个队伍做一些剧烈的弹性运动：劈腿、弓箭步、下腰、活动全身。
Sometimes his substrate teammates just need to be stressed and flexed into their transition state.
有些时候它的基质队友只需挤压和弯曲，就可进入过渡态。
So that's it. Remember that all reactions need energy to get going.
这就是酶。要记住，所有的反应都是需要能量的支持。
This energy is known as the activation energy.
这种能量就是活化能。
Enzymes lower that activation energy and speed the reaction through team MODS:
酶可以将需要的活化能降低，通过MODS小组加快反应速度：
microenvironment, orientation, direct participation, and straining bonds.
微环境、定位、直接参与、拉扯结合键。