Transcription
Step one is your body takes that fat and it crams a carnitine molecule on it, and that carnitine molecule escorts the fat across the membrane where it can get broken up. That's the key.
If you don't have the carnitine shuttle working well, then this won't happen, and then you've lost your fuel supply for 80 to 90% of your ATP. I mean, you could eat a bunch of medium-chain fatty acids. Good luck trying to live on that. That's not going to do it, right?
So, here's what I like this slide because it's this is, by the way, from the long-chain fatty acid disorder group. There's actually a long-chain fatty acid disorder group, believe it or not. You can just Google that and see these slides on your own if you want. But I like how they made this one black because this is the bad part. So, carnitine can get blocked here. Beta oxidation can also get blocked over here at this enzyme. There's a bunch of different places that it can go wrong. We won't maybe get too into the details on that. It's kind of interesting, but it's probably not that important because then change what you're going to do. But this part was important here. So, I want to dwell on this slide for a few minutes. Okay.
Now, uh, first, let's get oriented here. Here's the cytosol. Here's the outer membrane of the mitochondria and the inner membrane of the mitochondria. And here's the inside of the mitochondria over here. Okay, so blue is cell, all the way on the right is inside the mitochondria. So the mission here is to get your palmitate or palmitic acid. By the way, you can measure palmitate or palmitic acid on these labs, too. It's one of the fatty acids they measure. You got to get that the main fatty acids got to get way the heck over here so you can turn it into energy. And it can't just sneak across the membrane because it's too bloody long. And I'm just going to show you how big this thing really is. You see the palmitoyl-CoA? That's Oh, and there's our CoA again, by the way. Remember I said that was going to become important later. So, this is your palmitic acid combined with a CoA. Look how big that sucker is. It's huge. That can't get across the membrane. But you see the palmitoyl carnitine? See how teeny tiny that is? That can get across. This is the whole problem. Your body has to take the palmitoyl-CoA, knock that CoA off, cram on a carnitine so it can get through the membrane. It's just a size problem. That's it.
So, let's go back over to this one now. So, now once you understand the biochemistry here, it just makes so much sense. Here we have our palmitic acid or palmitate. It's now converted into palmitoyl-CoA, but your body's like, "Yeah, I don't think so, guys. It's too big." See that? It's too big. You cannot get across this membrane. No, no way. It's just too big. So, palmitoyl carnitine is formed. You rip off the CoA. You cram on a carnitine, and that palmitoyl carnitine slips right through that membrane using that particular uh transfer enzyme thing. Goes right through this translocase protein. It's like a like one of those um little shoots. you see on like a water park or something. Woo! It goes into there and all of a sudden, yahoo! You got your car, you got your fatty acid into the inner part of the membrane.
Now, what happens? Your body's like, "Okay, well, that was a lot of work. I'm going to get my carnitine back out." Carnitine goes back out to grab another fatty acid. And then here's our palmitoyl-CoA. You cram the CoA back on and then you start to make the fat. Do you see how complicated that is? It took me like two minutes to just explain that. So, every one of these steps something can happen. There can be a snip or an enzyme defect at any one of these steps which is going to mess this thing.