two proteins can interact with each other in conjunction with

兩種蛋白質可以在相互作用的同時

ATP to actually produce mechanical motion.

ATP 實際產生機械運動。

And the reason why I want to do this-- one, it occurs

我想這樣做的原因是-- 第一，我想到了

outside of muscle cells as well, but this is really going

肌肉細胞外，但這真的會

to be the first video on really how muscles work.

是第一部真正介紹肌肉如何工作的視頻。

And then we'll talk about how nerves actually stimulate

然後，我們將討論神經究竟是如何刺激身體的。

muscles to work.

肌肉工作。

So it'll all build up from this video.

所以，這一切都將從這段視頻開始。

So what I've done here is I've copy and pasted two images of

是以，我在這裡所做的就是複製並粘貼了兩張圖片，分別是

proteins from Wikipedia.

蛋白質來自維基百科。

This is myosin.

這是肌球蛋白。

It's actually myosin II because you actually have two

它實際上是肌球蛋白 II，因為你實際上有兩個

strands of the myosin protein.

肌球蛋白的鏈。

They're interwound around each other so you can see it's this

它們相互纏繞在一起，所以你可以看到是這樣的

very complex looking protein or enzyme, however you want to

看起來非常複雜的蛋白質或酶，無論你想

talk about it.

談談吧。

I'll tell you why it's called an enzyme-- because it

我來告訴你為什麼它被稱為酶--因為它

actually helps react ATP into ADP and phosphate groups.

實際上，它有助於將 ATP 反應成 ADP 和磷酸基團。

So that's why it's called an ATPase.

這就是它被稱為 ATPase 的原因。

It's a subclass of the ATPase enzymes.

它是 ATP 酶的一個亞類。

This right here is actin.

這裡就是肌動蛋白。

What we're going to see in this video is how myosin

在這段視頻中，我們將看到肌球蛋白是如何

essentially uses the ATP to essentially crawl along.

其本質是利用 ATP 來爬行。

You can almost view it as an actin rope and that's what

你幾乎可以把它看成是一根繩索，而這正是

creates mechanical energy.

產生機械能。

So let me draw it.

那就讓我來畫吧。

I'll actually draw it on this actin right here.

我會把它畫在這上面的

So let's say we have one of these myosin heads.

比方說，我們有一個肌球蛋白頭。

So when I say a myosin head, this is one of the myosin

所以，當我說肌球蛋白頭時，這就是肌球蛋白的一個

heads right here and then it's connected, it's interwound,

頭就在這裡，然後連接起來，相互纏繞、

it's woven around.

圍繞著它編織。

This is the other one and it winds around that way.

這是另外一條，從那邊繞過去。

Now let's just say we're just dealing with one

現在，讓我們只說我們只是在處理一件事

of the myosin heads.

的肌球蛋白頭。

Let's say it's in this position.

假設它在這個位置。

Let me see how well I can draw it.

讓我看看我能畫得多好。

Let's say it starts off in a position that looks like that

假設一開始的位置是這樣的

and then this is kind of the tail part that connects to

然後這是連接到

some other structural and we'll talk about that in more

一些其他的結構，我們將在更多的討論中

detail, but this is my myosin head right there in its

細節，但這是我的肌球蛋白頭，就在它的

starting position, not doing anything.

起始位置，什麼也不做。

Now, ATP can come along and bond to this myosin head, this

現在，ATP 可以與肌球蛋白的頭部結合，這個

enzyme, this protein, this ATPase enzyme.

酶，這種蛋白質，這種 ATPase 酶。

So let me draw some ATP.

所以，讓我畫一些 ATP。

So ATP comes along and bonds to this guy right here.

於是，ATP 出現了，並與這個人結合在一起。

Let's say that's the-- and it's not going to be this big

讓我們假設--它不會這麼大

relative to the protein, but this is just to

相對於蛋白質，但這只是為了

give you the idea.

給你一個概念。

So soon as the ATP binds to its appropriate site on this

一旦 ATP 與這一部位上的適當位點結合

enzyme or protein, the enzyme, it detaches from the actin.

酶或蛋白質（酶）會從肌動蛋白上脫離。

So let me write this down.

那就讓我寫下來吧。

So one, ATP binds to myosin head and as soon as that

首先，ATP 與肌球蛋白頭部結合，一旦

happens, that causes the myosin to release actin.

這就會導致肌球蛋白釋放肌動蛋白。

So that's step one.

這就是第一步。

So I start it off with this guy just touching the actin,

所以我一開始就用這傢伙碰了一下、

the ATP comes, and it gets released.

ATP 釋放出來。

So in the next step-- so after that step, it's going to look

所以在下一步--所以在這一步之後，它&#39；會看起來

something like this-- and I want to draw

我想畫

it in the same place.

在同一個地方。

After the next step, it's going to look

下一步之後，它將看起來

something like this.

類似這樣

It will have released.

它將發佈。

So now it looks something like that and you have the ATP

是以，現在看起來就像這樣，你就有了 ATP

attached to it still.

它仍然附著在上面。

I know it might be a little bit convoluted when I keep

我知道這可能有點複雜，當我一直

writing over the same thing, but you have the

寫的是同一件事，但你有

ATP attached to it.

ATP 附在上面。

Now the next step-- the ATP hydrolizes, the phosphate gets

下一步--ATP 水合，磷酸鹽得到

pulled off of it.

從上面拉下來的。

This is an ATPase enzyme.

這是一種 ATPase 酶。

That's what it does.

這就是它的作用。

Let me write that down.

讓我寫下來。

And what that does, that releases the energy to cock

這樣做的目的是釋放能量，讓公雞

this myosin protein into kind of a high energy state.

使肌球蛋白進入一種高能狀態。

So let me do step two.

讓我來做第二步。

This thing-- it gets hydrolized.

這東西會水解

It releases energy.

它能釋放能量。

We know that ATP is the energy currency of biological

我們知道，ATP 是生物的能量貨幣

systems. So it releases energy.

系統。是以，它能釋放能量。

I'm drawing it as a little spark or explosion, but you

我把它畫成一個小火花或小爆炸，但你

can really imagine it's changing the confirmation of--

可以真正想象它&#39； 改變的確認 -

it kind of spring-loads this protein right here to go into

它就像彈簧一樣，把蛋白質彈到這裡，然後進入

a state so it's ready to crawl along the myosin.

這樣，它就可以沿著肌球蛋白爬行了。

So in step two-- plus energy, energy and then this-- you can

是以，在第二步中--加上能量、能量，然後是這個--你可以

say it cocks the myosin protein or

說它會使肌球蛋白或

enzyme to high energy.

高能量酶

You can imagine it winds the spring, or loads the spring.

你可以想象它給彈簧上發條，或者給彈簧加載。

And confirmation for proteins just mean shape.

對蛋白質的確認只是指形狀。

So step two-- what happens is the phosphate group gets--

那麼第二步 -- 會發生什麼呢？

they're still attached, but it gets detached from

它們仍然連接在一起，但卻脫離了

the rest of the ATP.

其餘的 ATP。

So that becomes ADP and that energy changes the

是以，這就變成了 ADP，能量改變了

confirmation so that this protein now goes into a

確認，使這種蛋白質現在進入

position that looks like this.

看起來像這樣的位置。

So this is where we end up at the end of step two.

這就是第二步結束時的情況。

Let me make sure I do it right.

讓我確保我做對了。

So at the end of step two, it might look

是以，在第二步結束時，可能會出現以下情況

something like this.

類似這樣

So the end of step two, the protein looks

是以，第二步結束時，蛋白質看起來

something like this.

類似這樣

This is in its cocked position.

這是在上膛位置。

It has a lot of energy right now.

它現在精力充沛。

It's wound up in this position.

它被纏繞在這個位置。

You still have your ADP.

你還有你的 ADP。

You still have your-- that's your adenosine and let's say

你仍然有你的--那是你的腺苷，比方說

you have your two phosphate groups on the ADP and you

在 ADP 上有兩個磷酸基團，然後

still have one phosphate group right there.

那裡仍有一個磷酸基團。

Now, when that phosphate group releases-- so let me write

現在，當磷酸鹽基團釋放時--讓我寫下

this as step three.

作為第三步。

Remember, when we started, we were just sitting here.

請記住，當我們開始的時候，我們只是坐在這裡。

The ATP binds on step one-- actually, it does definitely

ATP 與第一步結合--實際上，它肯定會

bind, at the end of step one, that causes the myosin protein

結合，在第一步結束時，使肌球蛋白

to get released.

以獲得釋放。

Then after step one, we naturally have step two.

第一步之後，自然就是第二步。

The ATP hydrolyzes into ADP phosphate.

ATP 會水解為 ADP 磷酸。

That releases energy and that allows the myosin protein to

這樣就能釋放能量，讓肌球蛋白

get cocked into this high energy position and kind of

被喚醒，進入這種高能量狀態，有點像

attach, you can think of it, to the next rung

你可以想一想，到下一個梯級

of our actin filament.

的肌動蛋白絲。

Now we're in a high energy state.

現在，我們處於高能狀態。

In step three, the phosphate releases.

第三步，磷酸鹽釋放。

The phosphate is released from myosin in step three.

在第三步中，磷酸鹽從肌球蛋白中釋放出來。

That's step three right there.

這就是第三步。

That's a phosphate group being released.

這是一個磷酸鹽基團被釋放出來。

And what this does is, this releases that energy of that

這樣做的結果是，釋放出的能量

cocked position and it causes this myosin protein

它導致這種肌球蛋白

to push on the actin.

推動肌動蛋白。

This is the power stroke, if you imagine in an engine.

這就是發動機的動力衝程。

This is what's causing the mechanical movement.

這就是造成機械運動的原因。

So when the phosphate group is actually released-- remember,

是以，當磷酸鹽基團被釋放出來時 -- 記住：

the original release is when you take

原來的釋放是指當你把

ATP to ADP in a phosphate.

將 ATP 轉化為磷酸中的 ADP。

That put it in this spring-loaded position.

這使它處於彈簧加載位置。

When the phosphate releases it, this releases the spring.

當磷酸鹽釋放時，彈簧也會隨之釋放。

And what that does is it pushes on the actin filament.

其作用是推動肌動蛋白絲。

So you could view this as the power stroke.

是以，你可以把它看作是動力行程。

We're actually creating mechanical energy.

我們實際上是在創造機械能。

So depending on which one you want to view as fixed-- if you

是以，取決於你想把哪一個視為固定的--如果你

view the actin as fixed, whatever myosin is attached to

將肌動蛋白視為固定的，無論肌球蛋白附著於

it would move to the left.

就會向左移動。

If you imagine the myosin being fixed, the actin and

如果你想象肌球蛋白被固定，那麼肌動蛋白和肌球蛋白都會被固定。

whatever it's attached to would move to the right,

它所連接的任何東西都會向右移動、

either way.

無論如何。

But this is where we fundamentally

但這正是我們從根本上

get the muscle action.

獲得肌肉動作。

And then step four-- you have the ADP released.

然後是第四步--發佈 ADP。

And then we're exactly where we were before we did step

然後，我們又回到了原點。

one, except we're just one rung further to the left on

一個，只是我們在"...... "上又向左移了一步。

the actin molecule.

肌動蛋白分子。

So to me, this is pretty amazing.

所以，對我來說，這非常了不起。

We actually are seeing how ATP energy can be used to-- we're

實際上，我們看到了 ATP 能量如何用於--我們&#39；正在

going from chemical energy or bond energy in ATP to

從 ATP 中的化學能或鍵能到

mechanical energy.

機械能。

For me, that's amazing because when I first learned about

對我來說，這太不可思議了，因為當我第一次瞭解到

ATP-- people say, you use ATP to do everything in your cells

ATP--人們說，細胞中的一切活動都要用到 ATP

and contract muscles.

並收縮肌肉。

Well, gee, how do you go from bond energy to actually

那麼，天哪，你是如何從債券能量到真正的

contracting things, to actually doing what we see in

從承包事物，到真正做到我們在

our everyday world as mechanical energy?

我們的日常生活是機械能嗎？

And this is really where it all occurs.

這才是真正的關鍵所在。

This is really the core issue that's going on here.

這才是真正的核心問題。

And you have to say, well, gee, how this thing change

你不得不說，哎呀，這東西怎麼變了？

shape and all that?

形狀什麼的？

And you have to remember, these proteins, based on

你必須記住，這些蛋白質是基於

what's bonded to it and what's not bonded to

什麼與它粘合，什麼與它不粘合

it, they change shape.

就會改變形狀。

And some of those shapes take more energy to attain, and

其中一些形狀需要更多的能量才能實現，而

then if you do the right things, that energy can be

如果你做了正確的事情，這種能量就能

released and then it can push another protein.

釋放出來，然後就能推動另一種蛋白質。

But I find this just fascinating.

但我覺得這很吸引人。

And now we can build up from this actin and myosin

現在，我們可以通過肌動蛋白和肌球蛋白

interactions to understand how muscles actually work.

通過互動了解肌肉的實際工作原理。