For methionine to stimulate mTOR, it needs to donate a methyl group.

甲硫酸铵要激活雷帕霉素靶蛋白（mTOR）的作用就必须“捐献”出一个甲基组。

So, once methionine donates that methyl group, it becomes homocysteine.

所以，一旦甲硫酸铵“捐献”出甲基组，就会变成巯基丁氨酸。

Small chemical entities called methyl groups attach to stretches of DNA, which affects what sequences are active.

被称为“甲基原子团”的小化学实体附着在DNA片段上，这会对哪些序列是活跃的产生影响。

So if you have too much methionine, you'd have too many methyl groups and you could accelerate aging.

所以，如果甲硫酸铵过多，甲基组就多，甲基组一多就会加速衰老过程。

But, we have an amino acid called glycine that acts as a buffer for too many methyl groups.

但是，人体中有一种名叫甘氨酸的氨基酸，可抵消过量甲基组带来的负面作用。

Now what happens when we change out a hydrogen for a methyl group?

现在， 当我们将氢换成甲基时会发生什么？

One is there's a basic skeleton of that amino acid and on top of that, there's what we call a methyl group.

一部分是所谓的基础“骨架”，另一部分则是位于该“骨架”之上的甲基组。

The longest carbon chain is just 3 carbons long, so it's propane with one methyl group sticking off of it.

最长的碳链只有 3 个碳， 所以它是丙烷， 上面有一个甲基。

And the attachment with just one carbon that turns amphetamine into methamphetamine, that's the methyl group.

只有一个碳的连接将苯丙胺转化为甲基苯丙胺， 那就是甲基。

They're a phenyl group joined by a methyl group instead of just directly.

它们是一个由甲基连接的苯基， 而不是直接连接的。