Biochemistry Polysaccharides, Part 2

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

Today, we are going to continue our discussion of polysaccharides, and talk a little bit about cellulose, another polysaccharide; and we are also going to introduce these things called the glycosaminoglycans.0003

Let's get started.0015

OK, as far as cellulose is concerned, I thought we would introduce that with an example, get a little practice, a little more practice with drawing structures.0018

I hope I am not making you crazy with drawing all these structures.0028

It is very, very important to be able to handle them without any problems.0031

OK, let's start with, cellulose is a structure - remember we said that polysaccharides have many different things that they do.0035

One of the things was fuel storage with starch and glycogen.0054

Well, structurally, some polysaccharides …cellulose is one of the structural polysaccharides, homo, and it is a homopolysacch consisting of glucose, and this time, we have a beta-(1,4)configuration, beta-(1,4) glycosidic bonds.0058

We had alpha-(1,4) for starch and glycogen; now, we have beta-(1,4).0100

Just by changing the configuration- totally different molecule, totally different chemistry.0105

OK, what we want you to do is to draw a trimer - 3 individual monomers - in a Haworth projection.0110

OK, let's go ahead and draw our monomers.0126

We know we are dealing with a homopolysaccharide.0130

Let's go ahead and do this in blue.0132

So, it is just glucose, so let's draw out 3 glucose monomers.0134

We should be all pros at this already.0140

Beta-configuration, beta means we have the hydroxy up here.0146

Let's go ahead and draw each glucose before we move on to the next glucose.0148

And then, we have another one.0155

That is there, and beta-configuration, and this.0159

Oops, let me work from right to left.0164

This is down; this is up.0168

This is down, and this is CH₂OH; and, of course, we have one more.0169

Here we go, and this is beta.0176

This is down; this is up.0184

This is down, and we have CH₂OH.0186

And again, I tend to not draw the thickened lines simply because that is just sort of a habit that I have gotten into, but if your teacher wants them, they are there, if not, that is fine.0191

Here is going to be the connections.0204

Beta-(1,4)...let me go ahead and do it in black.0208

I have got my 1 carbon, my 4 carbon, my 1 carbon, my 4 carbon.0212

What is happening is the elements of water - this is a condensation reaction - the elements of water are going away.0217

This oxygen is going to connect to that carbon.0230

This oxygen is going to connect to that carbon.0234

This is going to be our beta-(1,4) glycoside bond.0237

Now, let's go ahead and draw that; I am going to draw this one in black.0241

I will go boom, boom, boom.0248

I am going to go ahead and draw in the trimer, and then I will go back and put on the individual substituents.0251

This is O, like that.0258

I should probably draw it a little bit bigger than that; sorry about that.0267

And then, of course, we have this, and this is going to go on that way; and this is going to go on that way.0272

Now, we can go ahead and fill it in: OH, OH, CH₂OH.0283

We have OH, OH, CH₂OH.0292

Let's make this one a little bit better, and we have OH, OH, and CH₂OH.0297

There we go; this is our basic trimer arrangement.0308

Notice they are all like this, and this is the glycosidic bond.0311

We have our beta-(1,4), beta-(1,4).0316

This is the beta right here, this and this.0321

We have drawn it, the bond this way, the bond this way, to show that this oxygen is actually up, beta; and this one is a down.0324

Now, I am going to go ahead and draw this not in another configuration, just a different representation of this actually showing the bonds a little bit more directly.0330

This is just another way of drawing it, and you are welcome to do it like this.0344

It is not a problem.0347

OK, so, we are going to have something like this.0349

I am going to start on this side, and let me do this in blue.0352

I have got, that is that; I have got O.0357

This is O; here, this is O.0370

This is there; this is there, something like that.0375

And, of course, it just sort of goes on like this.0380

That goes that way; that goes on that way.0384

And then, of course, we have our OH, OH, CH₂OH, OH, OH, CH₂OH.0389

All I have done is I have actually represented.0402

Instead of drawing them all straight like this, I have actually shown them in a sort of a stair step pattern just to show that more directly to the eye that this is below, this is above.0405

Let me go ahead and finish my substituents here, and I will go ahead and label some carbons.0418

Let's do that in black.0424

This is our alpha-1, no, not alpha-1; this is beta-1.0426

This is beta-(1,4); this is beta-(1,4).0432

The hydroxy is above the 4; the oxygen is below.0437

So, this is another way that you can draw it if you want to.0442

OK, now, I will do 1 final representation in order to show the geometry at the oxygen of the glycosidic bond, oxygen of the glycoside bond.0444

In other words, in order to show the geometry here, it is often drawn like this.0480

This is probably how you are going to see it in your book, at least one of the pictures...drawn like this as follows.0488

And again, you know oxygen, water, this is not a linear molecule; it is bent because we have these electrons here.0498

So, the geometry is a bent geometry; this is a linear geometry.0505

The picture before this, we had these curvy lines showing the arrangement, but now, in order to show the geometry, we are going to have to flip some of these monomers around.0509

Let's go ahead and draw what that looks like.0521

I am going to draw this one in black.0525

I am going to draw a central 1 first.0529

I have got that, that, that.0533

OK, I have got O, and I have got O.0537

Let me go ahead and draw my central 1 in here, CH₂OH.0541

Now, a little bit different, this is going to be there.0548

This time, I have got my O here, and I have got CH₂OH.0554

I have got OH; yes, that is correct, and of course, this one is going to be up.0566

And, of course, this one is going to be...let's just go ahead and put that there.0574

Let's put that there, and now, we will go ahead and put our O here, and we have our CH₂OH.0579

We have OH, and we have this O there, and that goes on.0593

I am missing an OH; yes, that goes right there.0599

So, notice what I have done; I have taken this one.0602

I have left it the same; let me do this in red.0606

I have taken this thing, and I have left it the same.0610

I have flipped this one down, in order that this bond, now, shows the normal geometry of oxygen.0614

By flipping it down this way, what I have done is I have brought the oxygen which is in the back right; now, it is in the front right.0623

Same thing, this one, I have flipped up.0634

I have just flipped it in order to show the geometry at that oxygen and that oxygen.0637

And again, same thing, what used to be an oxygen on the back right, is now, an oxygen on the front right.0643

In order that we can show the geometry, this is probably how you will see it.0649

And again, when you look at these things in your book, when you are looking through multiple structures, you want to make sure...a polymer of glucose can be any different kind of molecule, what is important is the nature of the glycosidic bond, alpha or beta, what carbon it is attached to.0656

And, what you are looking for in these structures if you are just looking at it as opposed to drawing it with your hand, you are looking for where this oxygen is in the ring.0675

That is what is going to tell you what molecule you are dealing with.0683

So, this one might happen to look like some other polysaccharide, a glucose, but you need to be very, very careful, and identify where the oxygen is and what the glycosidic bond is.0687

Here, you have your beta-1, and this is 4; and this is 4, and this is beta-1.0703

This is beta-1, and the reason it is beta-1 is, under normal circumstances where the oxygen is in the back right, the standard way we actually arrange things, the oxygen is up.0715

That is the beta-configuration, but by flipping it, now, the oxygen is below the ring; but the oxygen here is in the front right.0727

So, that confirms the fact that this is a beta-1 configuration.0734

Just by looking at the hexose, it looks like it is an alpha because the oxygen is below; but the oxygen is here.0737

The oxygen in the ring is down here, not back there, so this is a beta-configuration- very, very important.0743

OK, let's see what we have got.0751

Let's take a look here at some actual illustrations.0755

We have our standard here, beta right?0760

This is the beta-carbon; this is the beta-1, and over here, this is our no. 4 carbon.0767

But notice, this time, we have left this particular one on the left in the beta-configuration under normal circumstances, the standard Haworth projection with the oxygen on the back right.0775

This time what we have done is we have taken the other one, and we have flipped that.0789

Notice where the oxygen is; the oxygen is in the front right.0793

These are the things that we have to recognize.0796

We know that glucose 1, 2, normally 1, 2, 3, 4, the oxygen is below the ring.0799

Here, the oxygen is above the ring.0806

Well, it is above the ring because I flipped the molecule, flipped it like this.0808

Now, this no. 4 carbon, the oxygen goes up.0812

Again, this shows the geometry at this particular oxygen.0816

These are the things that we have to watch out for.0820

They are going to be drawn in any number of ways.0824

What we want to do is look and see what is where, and that will tell us what is happening.0827

OK, this particular vision right there, this is the same thing, except now, it is going to show some of the hydrogen bonding that takes place among the different monomers in a polysaccharide or an oligosaccharide.0832

So, in this particular case, we have some hydrogen bonding taking place here.0847

We have some hydrogen bonding taking place here.0851

This is hydrogen bonding within the chain itself, and the hydrogen bonding, in addition to the geometry in the oxygen, is going to dictate how this molecule looks in 3 dimensions, how it folds, how it spins this way, how it turns this way, how it bends this way; and that is going to have an effect on the chemistry.0855

That is the whole idea behind the organic chemistry.0878

Structure is function- that is the whole idea.0882

What this thing looks like in 3-dimensional space - the final shape that it takes - is going to dictate what function it serves.0885

Now, this is an extended network of hydrogen bonding.0893

So, we have hydrogen bonding within an actual chain, but in another chain, there is also some hydrogen bonding going on here and here and here and here.0897

Again, all of this, the net effect is that all of this has an effect on the final structure of a cellulose molecule, if you want.0908

I mean it is just an extended polymer- it is what it is.0922

It is not an actual molecule, but there you go.0925

You have the glycosidic bonds; you have the particular arrangements.0928

You have the hydrogen bonds within, among the individual monomers in a chain; and you also have a hydrogen bonding between the chains, and that is the whole idea.0933

Again, you have got hydroxys all over these carbohydrates, so clearly, there is going to be a lot of hydrogen bonding.0942

It plays very, very important role in the structure of carbohydrates.0948

OK, let's talk about a different family of polysaccharides.0953

These are called the glycosaminoglycans- very, very important.0960

OK, now, let's go ahead and this is going to be a bit long, but it should not be too bad.0977

Now, these are heteropolysacchs; up until now, we have been talking about homopolysaccharides.0984

We have been using just glucose.0989

These are heteropolysaccharides of the extracellular matrix.0996

Now, the extracellular matrix is just a fancy word for that jelly-like substance that is outside of the cells, that tends to hold cells in place.1006

You cannot just have cells wandering around everywhere.1015

Certain tissues are cells that are there; they are held in place.1019

They don't move around; they are held together by this thing called the extracellular matrix.1025

It is basically just a scaffold for these cells to be; it keeps them in place.1029

That is all it is; that is all you want to think about it as.1034

They are heteropolysaccharides of the extracellular matrix, which is a gel-like substance - probably the best way to think about it, just a gel-like substance - that provides support for cells - in animal tissues, anyway - in animal tissue, as well as, provides a porous network for the movement of oxygen and nutrients, OK, oxygen and nutrients to individual cells.1038

That is it.1110

OK, now, the glycosaminoglycans, I am going to actually abbreviate this as Gag.1113

You will also see this in your book.1127

The glycosaminoglycans, they form a family - linear heteropolysaccharides, heteropolysacchs - composed of repeating disaccharide units.1129

So, what you have is, it is a heteropolysaccharide, and that is has, in this particular case, it is made up of 2 monomers.1166

Those 2 monomers are going to alternate, so A, B, A, B, A, B, A, B.1173

You can think of a disaccharide, that A-B, as one unit.1176

You have A-B, A-B, A-B, A-B; that is what we mean by a heteropolysaccharide composed of repeating disaccharide units.1180

That is all it means.1189

OK, now, one of the disaccharide units, one of the disacchs, one of the monomers of the disacch, is either N-acetylglucosamine or N-acetylgalactosamine.1191

I am having a hard time writing today; sorry about that.1241

And, in a minute, we are going to start to use the abbreviations.1250

OK, the other monomer of this disaccharide unit, the other monomer, is most often a uronic acid; and uronic acid, for your quick recollection, if you go back a lesson or two, it is where the no. 6 carbon has been oxidized to a carboxyl group, COO^-.1254

And, the two that you will probably see are D-glucuronic acid - and don't worry, we are going to be going over the structures in just a minute, D-glucuronic acid or D-glucuronate for the one that has been deprotonated, which under physiological conditions, it actually shows up as COO^-, not COOH, so D-glucuronic acid and interestingly enough, the L-isomer of iduronic acid.1299

More often than not, these glycosaminoglycans, they consist of N-acetylglucosamine as one of the monomers, and some uronic acid as the other monomer; and those 2 units will alternate, and they will keep repeating.1332

Instead of the N-acetylglucosamine, you might have N-acetylgalactosamine.1350

Again, just another hexose, the hydroxy has just changed.1357

OK, one last thing before we start looking at some structures.1360

OK, in some of these Gags, in some of these glycosaminoglycans, one or more of the hydroxys have sulfates attached.1369

In other words, let's say you just have something like, let's say this one, CH₂, instead of the OH that has a sulfate attached- that is all.1403

It could be at this one; it could be at this one, this down, up, down.1423

It can be on this one; it can be this one.1431

It can be this one; it could be any two.1432

It could be any three; the different arrangement of the sulfates along this linear polymer actually becomes a site of recognition for different proteins.1434

So, the arrangement of sulfates, the number of sulfates, the density of them has different recognition, it serves recognition, function for proteins that need to bind to them electrostatically.1444

Obviously, if you have a bunch of sulfates, you have a high degree of negative charge, so there is going to be a lot of electrostatic interaction.1455

I just wanted you to know that in some of these, one of more of the hydroxys has a sulfate attached to it- that's it.1460

OK, let's take a look at some of these structures first.1468

Let's do this in black; let's look at the monomers.1473

Let's look at the monomers.1479

Now, we said N-acetylglucosamine, so that is going to look like this, this, that, that, boom.1490

Let's go ahead and do the beta version.1500

We have N; we have C.1503

We have CH₃; we have OH, OH, and we have CH₂OH.1506

This is N-acetylglucosamine.1513

This is the beta-D-N-acetylglucosamine.1518

Its shorthand is Glc - no, I need my N-GlcNAc.1529

That is N-acetylglucosamine.1539

OK, now, let's do the N-acetylgalactosamine.1541

We have got this, make it a little bit broader here.1546

Let's do the beta form, and again, we have an N.1551

We have a C, and a CH₃.1556

This is our N; this is our acetyl group.1560

This one is up, and galactose is a 1, 2, 3, c-4 epimer, so CH₂OH.1563

So, here, we have beta-D-N-acetyl…wooh, this is tiring, makes me crazy having to write all these stuff out.1573

This one is GalNAc.1586

That is the shorthand for that one.1590

OK, now, let's do our glucuronic acid and our iduronic acid.1592

Do I want to do them on this page or the next page?1598

You know what, I think I will go ahead and stay on this page.1600

Hopefully, there is enough room here.1604

I have got this; I have got that.1605

Alright, there is that; I will go ahead and do the beta, and this is there.1610

This is there, and this is there; and we said that the no. 6 carbon has been oxidized.1618

So, this one is our - that is what makes it - so, this is beta-configuration D.1625

D- hat is the configuration here and glucuronate.1640

Now, I did the glucuronate instead of the glucuronic acid.1645

The glucuronic acid would just be this protonated- that's it.1649

That is the only difference, so glucuronate.1651

OK, acetic acid, acetate, propanoic acid, propanoate, the A-T-E just tells me that I am deprotonated; and at physiological pH, I am going to be deprotonated.1654

This is beta-D-glucuronate glucuronic acid.1666

Now, let's do the beta-D-iduronic acid, the other particular monomer.1670

Let's see; let's go ahead and go here.1675

Let's see if I can do this one.1679

Alright, let's do this as a beta-configuration.1682

Now, this one is going to be OH.1686

This is a little different, and this is going to be OH; and here, we are going to have the COO^-.1690

Here, this is the L; remember, we said it is L.1700

This is beta-L-iduronic, iduronate or iduronic acid.1704

The L-configuration, remember, if we said any 2 substituents, we change configurations.1714

The D in the L is based on the chiral carbon that is farthest from the carbonyl.1723

The carbonyl carbon is this one; that is the anomeric carbon.1732

It is the no. 5 carbon - 1, 2, 3, 4, - that decides D or L.1735

D the CH₂OH, which is now carboxyl, is above the ring.1740

The L-configuration just switched the H and the CH₂OH.1745

Now, the CH₂OH, or which is now the COO^-, that is below the ring.1749

OK, this is L; this is D.1754

A galactosamine, in general, has one of these and one of these alternating.1757

Let's say we have N-acetylglucosamine and we have beta-D-glucuronic acid, A, B, A, B, A, B, that is going to be a particular glycosaminoglycan.1763

OK, let's see what we have got.1777

Now, and let me just write down one thing regarding the sulfate attachments.1783

Yes, that is fine; I will go ahead and write it down.1790

OK, regarding the sulfate attachments, I am just going to reiterate what it is that I said before.1793

The pattern of attachment provides for recognition by protein molecules which can bind electrostatically.1807

Now, protein molecules can also bind covalently, but in this particular case, it tend to bind electrostatically.1849

Oligosaccharides, polysaccharides, sugars, carbohydrates, on the cell surface, are how cells recognize each other.1858

The whole idea of recognition is all based on the arrangement of sugars on the cell surface- a particular configuration, a particular arrangement, 15 monomers, 27 monomers.1866

That is how individual body, individual cells recognize each other and communicate with what is happening inside the cell.1877

Glycobiology- profoundly important, and it is a fantastic, fantastic area of research that is only just beginning.1885

It is really only just beginning.1892

There is so much work to be done and so many wonderful new things to be discovered in this absolutely amazing, amazing field of biochemistry.1894

OK, let's take a look at some of these glycosaminoglycans.1903

Let's go ahead and go to blue; there we go.1907

Let's take a look at some glycosaminoglycans, some Gags.1913

OK, the first one we are going to look at is hyaluronic acid.1920

This is hyaluronic acid or hyaluronate, and this particular Gag is made up alternating monomers of GlcA and GlcNAc.1925

Oh, you know what, I think in the last page, when I did the glucuronic acid and the L-iduronic acid, I forgot to put the symbols.1957

So, this GlcA, that stands for the glucuronic acid.1969

That is the shorthand for glucuronic, and then, of course, we have the IdoA.1977

That is the iduronic acid; sorry about that.1985

OK, in this particular case, this particular glycosaminoglycan called hyaluronic acid, it has alternating monomers of glucuronic acid and N-acetylglucosamine- A, B, A, B, A, B.1992

OK, and here is the pattern of the binding for the glycosidic bond.2005

I am going to do this with 3 monomers.2010

Let me go ahead and do this in black.2015

This is going to be GlcA.2020

It is going to be beta-(1,3) - very unusual, very unusual - beta-(1,3) GlcNAc.2025

This one is going to be beta-(1,4); this is a little bit more normal.2033

And then, we have GlcA again, and then it goes on like that; and, it is going to be somewhere in the neighborhood of about 50,000 monomers.2037

It is a pretty long molecule.2049

Left to right, the glucuronic acid connected to the N-acetylglucosamine is connected by a beta-(1,3) glycosidic bond; and the N-acetylglucosamine connected to the next glucuronic acid is connected by a beta-(1,4) bond.2053

So, we have everything that we need right here in order to draw out the structure.2070

Now, let's go ahead and draw out the structure.2074

OK, let me start with a GlcA on this side.2076

Again, glucuronic acid, let me do this in black.2082

I have got this, that, that.2087

Now, let me go ahead and draw those two.2093

This is going to be the glucuronic acid.2102

This is going to be OH; this is going to be OH.2106

This is going to be OH, and this is going to be the COO^-.2110

That is the carboxylate.2114

Now, we said that it is connected in a beta-(1,3).2116

Well, this is the anomeric carbon.2119

Let me number these; this is the no. 1 carbon.2124

This is no. 2; this is no. 3.2126

Over here, what we have is...let me go back to black.2133

This is going to be the N-acetylglucosamine, so this is NH.2137

I am thinking in the last structure, I think I forgot the H on the nitrogen; sorry about that.2141

OK, this is going to be C.2145

This is going to be CH₃; this is down.2149

Now, here, on the no. 3 carbon, let me actually say the numbers until afterward; I think it is a little bit better.2153

So, here, this is going to be O, like that; and, of course, here, we have the OH, and we have CH₂OH.2160

Let me draw a couple of more of these, and then I will go ahead and discuss these particular glycosidic bonds on this molecule.2179

Let me see; let me go ahead and do this.2189

Let me go ahead and do that.2191

I will just make it a little bit quicker here.2194

COO^- and I’ve got an OH on top; I’ve got OH on the bottom.2197

This is glucuronic acid, OK.2203

I have got this one here, and I’ve got this.2205

It is going to be O there; this is going to be a CH₂OH.2214

This is going to be glucose, and this is going to be, this one is up, and this one is down; and let’s go ahead and leave it as beta.2226

Let’s just write 4 of those units right there.2237

OK, let’s take a look at what we have got here.2239

This is our GlcA, and this is our GlcNAc.2243

This is our GlcA, and this is our GlcNAc- glucuronic acid, N-acetylglucosamine, glucuronic acid, N-acetylglucosamine.2252

A-B, A-B- just keeps going in this direction and this direction; and the GlcA to the N-acetylglucosamine is beta-(1,3).2263

Well, here is our beta-1, and here is our no. 3.2271

Notice, beta-oxygen above 3 glucose, the no. 3 carbon, the oxygen is above the ring.2275

The hydroxy is above the ring, that is why we drew it this way; it is very, very unusual.2283

Now, N-acetylglucosamine connected to GlcA, with N-acetylglucosamine on the left, GlcA on the right, is connected with a beta-(1,4).2288

Well, here is our beta-1; this is our beta-1 carbon, and here is our no. 4 carbon.2299

And then again, GlcA to N-acetylglucosamine, it is going to be beta-(1,3).2304

This is our beta-1; this is our no. 3 carbon- that is it.2312

If you have this and if you know what the individual monomers look like, that is there, this is there, and that is there, and this is...oops N-acetylglucosamine, that is not right.2319

This is NH; sorry about that, COOCH₃.2334

Yes, I know; a whole bunch of carbons, oxygens, and things floating around.2341

It is very easy to lose your way as you can see.2346

OK, that is it.2348

Once we have this arrangement, once we know what is connected to what, we can draw up out structure.2350

If we are given the structure, we should be able to go backward; we should be able to recognize this is a uronic acid.2356

This is N-acetylglucosamine; this is a beta-1 configuration no. 3.2362

We should be able to write this out, you have to be able to go both ways.2366

OK, now, let’s talk about these hyaluronates or these hyaluronic acids.2370

Not only do they form part of the extracellular matrix, they actually form the lubricants for your joints, lubricants in your joints, and they also happen to give your eye that jelly-like consistency.2386

So, I can do that because of these hyaluronic acids.2407

Now, I am just going to go ahead and list some other glycosaminoglycans, and I am going to list them; and again, I am going to encourage you to use your book because it is your primary resource.2410

It is a fantastic resource with wonderful pictures and further discussion of what these individual glycosaminoglycans happen to do.2421

And again, we are just learning what these things do very, very recently.2431

Glycobiology, it is a brand; it is your definitely ground level if you want to get into glycobiological research- fantastic area.2438

Let me do this in blue here.2445

Other glycosaminoglycans, and I encourage you to take a look, maybe do a little bit of look on the web, look on your book- whatever it is that you need to do.2449

I am not going to talk about them again.2461

The only difference is you have different monomers, but it is always going to be a disaccharide unit.2463

It is always going to be an alternating A-B, A-B, A-B.2468

You are not going to have a C, a D, an F.2471

It is going to be, it is hetero, but there is only 2 monomers that make up this linear chain; and there is not going to be any branching.2473

Glycosaminoglycans, at least, not that we have discovered yet; I could be wrong.2482

That is the wonderful thing about biochemistry- you will never know what is going to happen tomorrow.2488

OK, some important ones, some of these you have actually heard off.2493

Chondroitin-4-sulfate, this chondroitin-4-sulfate, this just means that the hydroxy on the no. 4 carbon...so, if I just take some random 1, 2, 3, 4, either there or there.2498

I will not specify the stereochemistry.2516

OK, this could be glucose; it could be galactose, so I will just put OH here.2518

OK, it could be any stereochemistry, above or below.2521

This has been sulfated; that is all this means- 4-sulfate, chondroitin-4-sulfate.2525

Maybe it is 3 sulfate; maybe it is 6 sulfate that tells me the carbon that has been sulfated, the carbon that has the oxygen attached, that has the sulfate attached to it.2536

OK, chondroitin-4-sulfate generally tends to be in the range of about 20 to 60 monomers- very, very short.2548

These are a lot shorter than the hyaluronic acid; hyaluronic- they are huge.2555

These tend to be very, very short.2560

Keratin sulfate, somewhere in the range of maybe 25 monomers.2564

Heparin- definitely a molecule that you want to get to know well.2574

And, those of you that are going to be going on into medicine, you will get to know it very, very well.2577

Heparin, somewhere in the range of 20 to 90- a lot of variation.2581

OK, clearly these are much shorter.2588

You know what, I don’t need to write that; I mean, clearly, you know that these are much shorter, obviously.2600

We said that 50,000 versus let’s say 20 unit; yes, it is a lot shorter.2604

OK, these tend to be covalently linked to proteins.2610

So, if you run across a keratin sulfate, heparin, chondroitin-4-sulfate, any number of things, these will tend to be covalently linked to some type of a protein.2631

OK, that finishes our discussion of polysaccharides- almost, actually.2644

We have a little bit more to discuss, but that certainly finishes today’s lesson.2648

Thank you for joining us here at Educator.com.2652

We will see you next time, bye-bye.2653