Biochemistry Hydrolysis & Condensation Reactions

Hello and welcome back to Educator.com, and welcome back to Biochemistry.0000

So today's lesson, what I thought we'd do is take just a brief little sidestep, but I wanted to introduce two very, very important reactions that are going to come up all the time throughout the rest of the course; and they are the hydrolysis and the condensation reactions.0003

Up to now, we did this little chemistry review, where we talked about aqueous chemistry, where water is not just a medium, it's not just a solvent, where these reactions take place between these biological macromolecules and other things- it can actually act as a reactant or be produced as a product.0019

These are very, very important reactions.0039

They are ubiquitous in biochemistry, so I just wanted to introduce them, give you couple of examples of them, and then of course, as we go on in the course, you'll see them on a regular basis.0040

OK, let's see.0050

The first one- I'm going to give the definitions of both, and then I'm just going to just go ahead and give examples.0053

Hydrolysis will be our first reaction and it literally means breaking up by water - hydrolysis.0059

Hydrolysis, it is the use of water as a reactant - let me actually write H₂0 instead of water - the use of H₂0 as a reactant to split a single molecule into 2 molecules, 2 parts or 2 molecules, each of those parts will more often than not, be a molecule, where the components of water, of H₂0 - and again, it's best to think of H₂0 as an H⁺ and an OH^-, those are the two components of water - end up one on each molecule.0071

So, what happens is that water comes in, it breaks it up, and the H ends up on one molecule, the OH ends up on the other.0147

OK.0156

That's hydrolysis, and the reverse of that is called condensation, and you'll see why we use the term condensation in just a second.0157

You know condensation as, if you have a cold glass, you put it some place, the water in the air will actually condense onto the glass.0166

It goes from the gas phase to the liquid phase; you're actually producing water.0177

They call this a condensation reaction, and this you’ll see in a second, because you are actually producing water in this reaction.0180

Now, this is when two molecules react to form a single molecule, and where H₂0 is eliminated as a product.0187

In other words, the H from one molecule, the OH from the other molecule, are pulled off, they are stuck together and it's released as water.0226

So, once we pull them off and stick those together and release them of water, the two empty spaces, those two atoms, actually, and the bonding, so two molecules go to one.0235

OK.0245

Let's go ahead and just do some examples.0246

I'll just write here "These are the reverse of each other.".0248

If you know the mechanism of one, you know the mechanism of the other.0259

OK.0264

I'm going to go to blue to do my examples here.0265

Example 1, now, I'm going to write a hydrolysis reaction.0268

So, because of the reverse of each other, we can just choose a double arrow.0274

In forward direction, it's one type of reaction; in the reverse direction, it's the other type of reaction.0276

It just depends on which one you want to concentrate on, but I'm going to list them individually with just single arrows; and then at the end, I'll do an example with the double arrow - at least I think that's what I did.0282

OK.0292

Example 1: this is going to be the hydrolysis of ethyl acetate.0294

Now, hopefully, you'll remember a little bit of your organic chemistry, if not, we'll do it right here.0314

Ethyl acetate is an ester, and it looks like this.0319

Yes, that's fine, I'll go ahead and do it here.0325

When I draw my structures for organic compounds, I tend to draw out all the carbons.0328

Now, later as we go on, I'll probably end up drawing the line structures where two lines come in together, something like this.0333

This is a carbon, and that's a carbon, and that's a carbon, but for the time being, generally, even to this day, when I draw my structures, I tend to draw out all of the carbons because I’d like to see all of my carbons.0339

Actually, you know what I'm going to do, I'm going to go ahead and do this on the next page; excuse me.0354

I'll go ahead and leave this here.0358

Example 1: hydrolysis of ethyl acetate.0360

Let me go ahead and go to the next page.0362

This is the hydrolysis of ethyl acetate.0365

Let me rewrite it - hydrolysis of ethyl acetate - and it's going to look like this.0369

We have CH₃, COO, CH₂, CH₃ - this is the ethyl part, this is the acetate part, it is an ester, ester is a carbon; it has this carbonyl group, and on that carbon, the carbonyl carbon, there's an oxygen, and that oxygen is attached to another carbon group, OK – plus H₂O, it goes to CH₃, COOH, + HO, CH₂, CH₃.0381

There we go; we've taken a single molecule, we've split it.0424

Now, let me do this one in red.0427

This hydrolysis, we've actually split it.0429

Now, notice, we split it actually right here.0432

OK.0434

That's where the hydrolysis takes place.0436

We are not going to worry about mechanisms just yet, we'll get to mechanisms a little bit later, but I just wanted you to recognize these reactions.0438

But notice, this oxygen over here is not this oxygen.0443

This oxygen actually comes from the water.0449

And again, we'll deal with mechanism later but the bond that we split is this one right here, and here are the elements of water.0452

There is your HOH, or actually, it's not that, that's just the reverse of what it is that I said, so let me erase this.0460

You can look at it that way.0472

Let me go back to blue and rewrite everything, so I have it in there.0477

There is an O here, and then H here.0480

OK.0484

Now, let me go to red, and my elements of water are right there.0485

You could have done it the other way, it's not a problem, but I just wanted you to realize that this OH, actually, this oxygen comes from the water; but again, that's a question of mechanism which we'll deal with later.0493

So, this is the hydrolysis- you are using water to split a molecule into two molecules - acidic acid and ethanol.0502

That's all.0511

OK.0512

Now, let's go ahead and see what we can do.0514

Let’s do example 2.0520

Now, we'll do the reverse; now, we'll do the condensation of acidic acid with ethanol.0526

We are going to do the reverse reaction.0540

We are just going to write it backwards, just the other way around.0542

What we have is CH₃, COOH⁺, HO, CH₃, CH₃.0545

So, now, in this case, when this molecule of acidic acid and this molecule of ethanol come together, the elements of water are going to be released.0563

What you end up with is the ethyl acetate: CH₃, COO.0572

You're probably wondering why didn't I just put the double arrow here?0579

Why do I have to rewrite it?0581

Well, part of it is just practice.0582

The idea is: it's one thing to see something on the page and think that you understand it; it's another thing to actually write out the structures and understand it.0585

The only way that you have full command of the material in your mind is if you are actually able to produce it with your hand.0594

That's why it is important, even for me at this point, I like to write things out.0600

Yeah, it takes a little bit longer, yeah I think that I understand it, but I know that when I write it out, when I produce it actively, it's very, very different than understanding it passively just by looking at it; so write things out, get in the habit of writing things out.0604

It is a little tedious, it is a little annoying- I know.0617

Biochemical molecules are going to get bigger and bigger and bigger, but if you want to have a total command of your biochemistry, which you want to have if you are going to go on in the biomedical sciences, you need to write them out.0620

Trust me on this one- active understanding better than passive understanding.0631

OK, sorry.0636

Alright, so this is going to be O, and then let's go ahead and write CH₃, CH₃ - we're doing the condensation, right, yes - + H₂O.0638

OK.0650

Where are the elements of water that are coming together?0651

I'll do this in blue now.0655

Here, again, this is the bond that's being broken.0658

That's the bond that's being broken.0661

We won't worry about mechanism.0662

Those are the elements of water.0665

This H and this OH, they come together to form that water.0668

OK, good.0676

OK, let's do example number 3 here.0678

I wonder if I should do it on the next page; that's alright.0683

Example number 3, I think I've got enough room here.0686

This is going to be the hydrolysis of adenosine triphosphate, the hydrolysis of ATP.0689

Now, we'll talk about ATP later when we talk about bioenergetics.0699

Let me write the equation first - ATP 4- - and then, I'll do the structures.0703

Again, this is biochemistry, organic chemistry structures.0708

ATP + H₂O is going to go to H, ADP, and I'll explain where that H comes from in just a minute.0713

2- + HPO₄^2- - notice the charges' balance 2-, 2-, 4- on the right, 4- on the left.0722

It's very, very important.0731

Here is what the reaction looks like.0733

I'll write AD for adenosine, and here is what the triphosphate looks like: O, P, O, P.0737

And again, no worries, this is not about getting the structure here right now, and just recognize the hydrolysis and the condensation reactions.0745

We'll worry about what these look like later.0754

O, P, O, P, O, P, O and then we've got a double bond there, a double bond there, a double bond there.0755

We have a minus charge, a minus charge, a minus charge and a minus charge.0765

There are normally hydrogens on all of these; it's fully ionized.0769

OK.0773

It's fully ionized at body pH, so this is a 4- charge; that's what this is.0775

Now, plus H₂O, this is going to be the hydrolysis part.0780

OK.0786