and you've switched it from an 'off' position

你就能够将酶从无催化作用的静息态
where it's not catalyzing a reaction to an 'on' position where it is,

激活至能催化反应的激活态
you've changed the biochemical state of the cell,

你改变了细胞的生化状态
you've changed the chemical reactions that can occur within the cell,

也改变了细胞内发生的化学反应
and you've changed its behavior.

改变了细胞的行为
That's a very simplified version of why kinases are important.

这就是激酶为什么如此重要的原因
Well, if this kinase happens to turn this protein on

那么在激酶激活蛋白质后
then you would like to have a mechanism to turn it off as well.

你会希望有一种方法能够使它失活
The other beauty about - beautiful thing about proteins

蛋白质的另一个美妙之处就是
is that if you make subtle conformational changes,

如果蛋白质发生一些小的构像改变
often those changes are reversible.

这些改变通常是可逆的
Now, you all know that we can make irreversible changes in proteins,

现在你们都懂蛋白能够发生不可逆的改变