Metabolism | Triglyceride Synthesis

All right, Ninja Nerds. In this video, we're going to go over triglyceride synthesis. So, if you guys have already watched the video on how we actually synthesize the fatty acids, it's going to be very, very important that you guys have watched this before you watch this video.

Okay, so let's go ahead and dig right into it. So, if you guys remember, what are the constituents of making triglycerides? Well, one thing is we need fatty acids.

So, here what we have is we have three fatty acids, okay? Okay, but they're specifically called fatty acil coas because they have that co-enzyme A on them. Now, what we're going to try to do is we're going to take these fatty acids and link them up to this chain right here, this threecarbon foundation.

And this molecules called glycerol. So, so far we need two things in order for this process to work. We need these three guys here which are all called our fatty ac.

So, these are our fatty acal cos. One, two, three. because in order to make triglycerides we need three fatty acids.

Then we're going to have this molecule here and this is going to be our glycerol. These are the constituents to synthesize triglycerides. And you know another word we give uh for synthesizing triglycerides they also call it lipogenesis.

So another name for it is actually specifically called lipo genenesis and that's what we're going to be talking about in this video. Okay. So if you guys remember we synthesized the fatty coas with the malanil coa acting as the precursor with those fatty acid synthetase enzymes and going through all those different steps with the ail carrier protein and the cyine tholin.

Now that we've done that we've synthesized our fatty acids. Okay, now that we've synthesized them, we're going to want to link these guys up. In order for us to do that though, we need to understand something.

We didn't really talk much about the glycerol. Where can that glycerol come from? Well, you know, it can come from just the atapose tissue.

So, if you guys remember specifically from just the atapose tissue, let's say I put over here a couple different adypo sites. So, here's a couple adipo sites. And if you guys remember, we could actually break these uh triglycerides down, right?

And one of the constituents that we can get out of that is glycerol. That's one of the constituents we can get glycerol. And what was this from?

This was from lipolysis. Where else can we get the glycerol? You know from the glycolysis there's a specific point in the glycolysis pathway.

So let's say here I have glycolysis pathway. And a specific point in the glycolysis pathway is you form a molecule called dihydroxy acetone phosphate. and that dihydroxy acetone phosphate if you guys remember he was able to be converted into this glycerol molecule.

So let's show how this happens. So this dihydroxy acetone phosphate can be converted into glycerol. In order for that to happen though I need to take and drop off some hydrides.

So I need to take NADH's that I've generated and convert them into N A positive. So what am I doing? I'm dropping off hydrides onto this dihydroxy acetone phosphate and converting carbonial into alcohols.

But another thing is this guy has a phosphate on a specific carbon. We're going to have to put a phosphate on one of this guy's carbons too. So if we were to number this glycerol 1 2 3 carbon chain right on the third carbon of the alcohol there should be a phosphate group coming off of it.

So what should be coming off here? There should be a phosphate group coming off. So now what do we specifically call this?

We call this glycerol 3 phosphate. That's what we really should call it, right? We should technically call this glycerol 3 phosphate.

Before we do that though, let's actually show that in in an actual singlestep reaction. Let's do that in a singlestep reaction. So, let's put the alcohol back on here.

And then let's use a specific enzyme. Technically, there's technically a specific enzyme that can do this step right here. We're going to show it as a separate step here.

I'm going to take this glycerol and I'm going to have a special enzyme. And this enzyme is called glycerol kynise. It's only present in the liver, right?

And what this glycerol kynise is going to do is it's going to put a phosphate on the third carbon of glycerol. So let's say I take this phosphate here and I feed it into this reaction here. Okay.

Now what is going to happen? Now let's draw our glycerol over again here. Our three carbon unit here, right?

With our hydrogen there, our O here, carbon, O carbon. But then we have that oxygen there. Let's draw all our hydrogens.

And then now what should be linked to this oxygen, guys? There should be a phosphate. Now what is this molecule here called?

This molecule is called glycerol 3 phosphate. So technically, if we really wanted to be particular, we could actually erase this step here from DHAP going to glycerol because technically if you guys know DHAP is actually converting into glycerol 3 phosphate. So we should actually show that over here.

And then again, what are we generating in this step? We're taking NAD H dropping off the hydrides to form NAD positives. Okay, so we got the dihydroxy acetone phosphate into the glycerol 3 phosphate and that can be done straight from DHAP from glycolysis to glycerol 3 phosphate or we can take from the atapost tissue.

You know the atapost tissue has the triglycerides and when you break them down you break it into glycerol and fatty acids. What we can do is we can use the glycerol here and I have an enzyme called glycerol kynise and glycerol kynise can convert glycerol into glycerol 3 phosphate. Okay.

Now the next thing that we have to do here then we have to take this glycerol 3 phosphate and combine it with each one of these fatty accoas. So now what I'm going to do is I'm going to draw the glycerol in a large view here. So now we're going to take this glycerol step by step here.

So, let's say here we have our carbon. I'm going to draw it like this now. And I'm going to put my O's right here.

And again, on the third carbon, I shouldn't have an O. I should have a phosphate group coming off. Let's draw all the hydrogens's coming off of this puppy.

Okay, there's our hydrogen there. There's our hydrogen there. Okay.

And again, let's number it just so we know exactly where we are. One carbon, two carbon, three carbon. But you would know that because on the third carbon there is a phosphate group.

Okay. Now, what's the first step? The first step is I'm going to number each one of these fatty acids.

I'm going to number this fatty accoa number one. I'm going to number this fatty accoa number two and this fatty coa number three because we're going to add each one of these on in sequence because it's very particular in the way we have to do this. So, the first thing we're going to do is we're going to add this fatty accoa onto the number one carbon.

So, now I'm going to take this guy here and I'm going to add it onto that one carbon. So, let's show that. So this guy right here is going to come in and it's going to be added onto that one carbon.

Okay? Then if you want to be particular, this guy here would be added onto the second carbon. And this guy right here would be added onto the third carbon.

But there would have to be a specific sequence of actions of how this is being hap how this is happening. So now what we're going to do is we're going to show this in a sequence of steps of how it's going. Okay.

So now let's have our carbon group here. hydrogen, hydrogen, hydrogen, hydrogen, hydrogen again. And then let's have our O here.

O, and then again our oxygen with the phosphate group. Okay, so let's take that first fatty acil that we're going to call fatty acila number one. So we're not going to show that whole structure.

We're just going to say specifically this one is going to be fatty ail coa number one. I'm going to add this guy into this guy here. So I'm going to take and fuse these two guys together.

But when this guy reacts with this guy, we're going to specifically again let's get our carbon straight here. Again, this is carbon one, carbon 2, and carbon 3. this fatty acco number one and this glycerol is going to be acted on by a special enzyme and this enzyme is called a seal transferase.

So it's not hard to remember because this enzyme is transferring a fatty acal coa on here and what are you going to lose? You're going to lose a co-enzyme A out of this reaction. So you lose a co- A but this fatty acco number one is going to be add on to the number one carbon.

So now let's show that. So boom, boom. And again, I'm going to have my hydrogen here, hydrogen here.

Still going to have my phosphate group there. That hasn't changed. But now look what's going to be different.

Now on the first carbon, I'm going to have my oxygen there. But now what am I going to have? I'm going to have this fatty accoed to it, but without the COA.

So let's draw that. So now what am I going to have? I'm going to have carbon double bond oxygen and this is going to have a CH2 14 carbons like that with a CH3.

What do I call this molecule? This molecule is called lyso phospha phosphotic acid. So this first molecule that we just formed is called lyso phospha titic acid.

Okay, so that's the first one that we formed. We formed our our lysophospatitic acid. Okay, now that we formed our lysophospatitic acid, let's do the second step.

So now in the second step, it's just going to be the same thing. So look here in the second step. In the second step, what am I going to be adding here?

I'm going to be adding the second fatty acil. I'm going to add this guy. So I'm going to add fatty acila number two.

So these two guys are going to react. But again the enzyme that's catalyzing this step here is still going to be a ail transferase enzyme. So what is the enzyme triggering this reaction to occur?

Again the enzyme is going to be specifically a ail transferase enzyme. Okay. And again what are you going to lose out of this step here?

You lose a co-enzyme A. So out of this will come a co-enzyme A. Now, let's draw this new molecule right here.

So, now we're going to have our carbons of all the hydrogens attached here again. But now, if I redraw this guy here, we have our first the fatty acid added on here. And then what are we going to have?

We're going to have another fatty acid added on. So, now let's add this next fatty acid. So, how does this reaction occur?

I'm going to add in this guy here. But here's the key thing. What do you notice the difference between these this guy and this guy?

This guy has double bonds. So, he's an unsaturated fatty acid. This is a saturated fatty acid.

Saturated just means that it has no double bonds. Unsaturated means it has a double bond. If it's monounsaturated, has one double bond.

If it's polyunsaturated, it could have many double bonds. The critical thing is that the second fatty acid added has to be unsaturated. Okay.

Okay, so now we're going to add on this second fatty acid, but it has to be unsaturated. So now let's add that on. So now we're going to have again the carbonal.

And then what does it have? Has a CH2. Then it's going to have a CH2, but seven of them like that.

Then you're going to have a carbon which has a double bond with another guy. And then what? Then you're going to have a CH3.

This is our next molecule. What is this guy here called? This guy is specifically Let's draw our oxygen here with the phosphate group.

Need to be consistent with our molecule here. This should have a phosphate. This should still have a phosphate.

And again, this was called lysophospatitic acid. This is just going to be called phospatitic acid. So this molecule is called phospha titic acid.

I keep spelling my things wrong. Phosphotic acid. Okay, so we got phospatitic acid comes after and then there was lysophospatitic acid and before that we just had the glycerol, right, as our basic unit.

Glycerol 3 phosphate last step. Now what we're going to do actually there's two more steps but it's going to be simple. We're going to combine these two steps together.

If I combine two steps together, I'm going to do the same thing I did in the first two steps. So again, this was step one where I added fatty accoa number one. This was step two where I added fatty acila number two.

In the third step, I'm going to do two things. I'm going to add in what you guys already know. I'm going to add in my fatty ac.

And what am I going to lose out of the process of this? I will lose a co-enzyme A. So, I'll lose a co-enzyme A out of this process.

Co-enzyme A. But here's the kicker. Look, can I add that fatty accoa onto this end?

No, because there's a phosphate there. So, I can't get that I have to get that phosphate off first. So, what do I have to do before I add the fatty accoa?

I have to bring in a special enzyme. What is the special enzyme? The special enzyme is called a phosphatase phosphotase.

And what's this phosphatase going to do? So, technically it's a phospatitic phosphatase. It's going to come in and it's going to cut that bond right there.

It's going to cut this bond here and it's going to release out a phosphate. So again, what enzyme is going to do this? A phospatitic phosphotase will cleave that phosphate off of the third carbon.

So what am I going to release out of this reaction? I'm also going to release a phosphate. Then I'm going to add the fatty coa number three onto the third carbon here with the oxygen.

Right? So now let's draw our finished triglyceride product. So again I'll have let's draw it here in an angle.

Carbon hydrogen carbon hydrogen carbon hydrogen and another hydrogen. And again let me draw all my oxygens here. And now let's draw our finished product.

The first one had specifically a carbonal with a CH2 14 of them like that and then a CH3. The second carbon had specifically what? It had a carbonal with a CH2.

Then it had CH2. Seven of them like that. Then it had a double bond and then a CH3.

And the last one specifically had what? This one is going to be exactly the same as the first one. So what are we going to have here?

Carbon double bond oxygen CH2. 14 of them like that. and then CH3.

What is this molecule here called? This is called a triglyceride. But sometimes they refer to triglycerides, they give them a different name.

They call it a triacal glycerol. Okay? Sometimes you might even see it referred to as a triacal glycerol.

So be prepared to hear either one of those terms because a triacal this is a fatty acal. This is a fatty acal. This is a fatty acal.

So we're adding on fatty acal groups. So you can call this a triacal glycerol or just a triglyceride because you know another way that we can name these. Technically this one is a um specifically a monoglyceride or a monoaclycerol.

This one is technically considered to be what? A dia glycerol and this one is a triglycerol. So I can also kind of name these different names too if I want to.

I could technically call I could call this one a DAG which stands for diasal glycerol for this molecule right here and I could technically call this one a mag a mono acil glycerol and again this one is a triasogglycerol. All right so this covers the the triglyceride synthesis. Now the next question is and we're going to cover this when we link this to cholesterol metabolism is what can I do with these triglycerides?

Well, these triglycerides can actually be packaged into special different types of lipoprotein molecules. Those lipoprotein molecules that we're going to package them in is going to be called very lowdensity lipoproteins. So, what we're going to talk about in another video is specifically me taking this triglyceride and packaging them into special structures.

And again, what is these special structures? So let's say I draw it here and I can put this whole triglyceride which I'm going to just uh draw now in a different way but meaning the same concept here. So now let's have a green fatty acid, we'll have a blue fatty acid, and we'll have a black fatty acid.

And this is going to be in a specific type of lipoprotein molecule with specific types of apoproteins, which we'll talk about. And this is going to be called a VLDL. And where can this VLDL go?

it can take and transport this triglycerides and a tiny little bit of cholesterol to atapost tissue where it can be deposited into the atapost tissue and stored as triglycerides. So again, where could this VLDL go? This VLDLDL could come over here where it could come over here and do what?

It could be transported through the bloodstream and then deposit those triglycerides into the atapost tissue. So what is it going to throw in here? It's going to throw into the atapost tissue.

I'm just going to draw it here in a general way guys. It's actually going to get broken down by lipoprotein lipase. But what's going to happen is it's going to get taken into these adyposytes and then reynthesize back into triglycerides where they can be stored.

Okay, so just a really quick recap again we need glycerol as our basic unit which can come from glycolysis from the DHAP or it can come from the actual breakdown process from the atapost tissue like lipolysis. And again this is also can happen a little bit in the liver but not too much. But then the glycerol what can happen only in the liver you have this glycerol kynise enzyme which does what converts the glycerol to glycerol 3 phosphate which is the basic unit for what for these fatty accoas to be added and what did I do I added each fatty accoa in a sequence one two and three and again what would be the enzyme I didn't mention here but it's the same enzyme that we mentioned in all of these ail transferase in third step again but all you're doing is you're adding these fatty acal coas in sequence with an ail transferase present okay converting it into what So taking glycerol adding a fatty coa and going into lysophospatitic acid or a monoil glycerol.

Taking that lysophospatitic acid or the monoyglycerol and taking another fatty cocoa adding that in with the ail transfor transferase and forming phospatitic acid or dicilglycerol. Taking that phospatitic acid and dia glycerol doing what? Getting rid of the phosphate with the phosphatase enzyme and adding another fatty accoa with another what what is that enzyme again in this step?

ail transferase and again what do you form? You form a tricoglycerol. What can we do with these tricogglycerols?

Specifically, you're going to take these triogglycerols in the liver and package them into special lipoprotein molecules called very low density lipoproteins. And where do they take that triglycerides? They take them to the atapost tissue.

They have a specific protein on their membrane that recognizes a specific enzyme here called lipoprotein lipase which cuts the triglycerides and releases them into the atapose where they be reynthesized back into triglycerides and stored when we need to utilize them again. All right engineers, so in this video we cover triglyceride synthesis. In another video we'll kind of talk a little bit more about these lipoproteins when we discuss um uh specifically the cholesterol metabolism.

All right engineers, I hope it all made sense. I hope you guys enjoyed it. If you did, hit the like button, subscribe, and leave a comment down in the comment section.