Myoglobin vs. Hemoglobin

In this video, we're going to formally introduce myoglobin and hemoglobin so as you guys may already know, both myoglobin and hemoglobin are proteins that are respectively abbreviated with M B and H B, and so moving forward in our course, we're going to use M B and H B a lot to abbreviate, myoglobin and hemoglobin. Now the reason that your professors in your textbooks like to focus so much on myoglobin and hemoglobin is because both of these proteins are very well studied proteins whose functions and characteristics have been very well characterized. And not only that both myoglobin and hemoglobin are great examples for many of the protein and enzyme concepts that we learned about in our previous lesson videos. And so here we're going to be applying a lot of those older concepts directly to myoglobin and hemoglobin. Now, technically, myoglobin and hemoglobin are not enzymes, and that's because they do not catalyze a reaction and convert substrate into product. However, myoglobin and hemoglobin do bind to a lie ganso protein ligand interactions applies directly to both myoglobin and hemoglobin. Also, it's important to note that Alice Derek Regulation does not Onley apply to enzymes. It can also apply to proteins that participate and protein Liggan interactions. Now, myoglobin, as you guys may already know, is a mono merrick protein, meaning that it only has one protein sub unit. Mono means one. And so, if we take a look at our image down below on the left hand side over here, notice that we have this brown structure here and this brown structure on Lee shows one sub unit one, uh, chain. And this is representing myoglobin structure now myoglobin. Its function is really to facilitate oxygen diffusion storage and supply to muscle tissues. Invertebrates. Now, hemoglobin, on the other hand, is a hetero tetra Merrick al assed Eric protein, and that's a handful. But really, if we break it down, it's not very complicated at all. So Tetra is a prefix. That means for and so essentially, what this is saying is that hemoglobin has four different poly peptide chains for different sub units, and then the hetero here, of course, just means different, meaning that not all four of these subunits are exactly the same. They're going to be somewhat different and in fact, if we break down these four sub units that are found in hemoglobin structure. We'll see that it actually has to sub units that we refer as Alfa sub units, and it has to sub units that referred to as beta subunits. So the two beta subunits are identical to each other, and the two Alfa subunits are identical to each other. But obviously the alfa and beta subunits will be different, and that's why we refer to it as hetero and so really hemoglobin. Its function is to circulate and transport oxygen via the blood. And so if we take a look at our image down below, noticed that we have hemoglobin structure over here on the right and notice that it has to Alfa sub units here in red. And then it has to beta subunits here and blue, and so you can see that hemoglobin is indeed a hetero tetra America protein. And not only is it a hetero tetra merrick protein, but again, I want to emphasize that it's also an al assed eric protein, meaning that all of the Alice Terek concepts that we learned about in our previous lesson videos also applied to hemoglobin, and we'll be able to focus more on those Alice Terek concepts of hemoglobin a little bit later in our course. Now, what's important to note is that both of these proteins, hemoglobin and myoglobin are capable of reversible e binding to oxygen gas, which we're going to abbreviate as just oh, to moving forward in our course because that's the molecular structure. And so the reason that both of these enzymes are capable of reversal Lee binding oxygen gas is because both of them have what's known as a khim prosthetic group. And so notice that myoglobin Team prosthetic group is represented by this little alien disc structure that we see right here. And so it turns out that myoglobin, uh, structure only has one team group for its one sub unit. However, if we look at hemoglobin structure over here on the right, noticed that it actually has four of these khim groups. And so it has won him group per sub units. So, uh, it turns out hemoglobin has mawr heem groups than myoglobin, but they both do indeed have him groups, and it's the same group that allows both of these proteins to bind oxygen. Now again, I really wanna emphasize the fact that although myoglobin and hemoglobin need to be able to bind oxygen. It's also equally it is important for them to be able to release oxygen when the time is right. And so really, this is what we're referring to as reversible binding of oxygen. Not only do they need to be able to bind oxygen, but they need to be able to release the oxygen as well. And so we'll talk more about this reversible binding of both of these proteins later in our course now down below. Noticed that for myoglobin over here on the left were emphasizing the fact that its function is for oxygen diffusion and storage, specifically in muscle tissues like this bicep here that we see. And hemoglobin, On the other hand, which we have over here on the right, Its function is for oxygen circulation and transport specifically, and the blood. And so here you can see that we're zooming in on the bloodstream and so hemoglobin as well, uh, note more about later is actually found inside of the red blood cells that we see here. Now, over here on the right, what we have is a mawr chemical version to represent myoglobin and hemoglobin and again. Remember, MBI is used to represent myoglobin, whereas HB is used to represent hemoglobin. And so when M. B is written in this form here, it's usually referred to as D oxy myoglobin because it's not attached to the oxygen molecule just yet. And the same goes for hemoglobin. When it's just written as H B. It's the D Oxy hemoglobin form, and so notice that myoglobin because it only has one of these him groups. It's only capable of binding one oxygen molecule, and it forms M B 02 over here, and this would be referred to as the Oxy Myoglobin because it's now been oxygenated, whereas hemoglobin down here below notice that it can actually bind to four oxygen molecules. And that's because it has four of these heem groups. And so when hemoglobin binds these four oxygen molecules, its chemical formula turns to this format here, where it has four of these 02 molecules bound. And so this is the Oxy hemoglobin format. And so this here concludes our introduction to myoglobin and hemoglobin, and we'll be able to continue to learn a lot more about both of these proteins as we move forward in our course. So I'll see you guys in our next video

in this video we're going to talk about. Myoglobin is protein ligand interactions and so protein Ligon affinity, which is most commonly represented by the dissociation, equilibrium, constant capital, K D, as well as the fractional saturation, which is abbreviated, is either theta or why both applied directly to myoglobin is protein, leg and interactions. And so recall from our previous lesson videos that the fractional saturation theater or why is really just a ratio. It's the ratio of the proteins bound by Liggan over the total concentration of protein. And so when we apply this specifically to my globe and we can say that the fractional saturation of myoglobin is just the ratio oxygenated protein, which would be the protein like in complex over total protein, which again is, uh, the protein bound by Lagan, as well as the protein not bound by law again and so down below in our image, notice that we have it broken up based off of what is review from our previous lesson videos. And then what is new here as it directly applies to myoglobin and so which will notice is that it translates pretty much perfectly over to my global what we learned in our previous videos. And so notice here. What we have is the protein ligand interaction from our previous videos. And so when we apply this directly to myoglobin, you can see that we substitute the protein with myoglobin specifically the d Oxy form of myoglobin. Then we have the lie again is next. And of course, the lie again for myoglobin is going to be the oxygen gas molecules and then we have these set of equilibrium arrows with the rate constant, the association rate constant lower case K and the dissociation rate constant lower case K d. And of course, the protein, leg and complex is going to be myoglobin. And it's oxygenated form. So Oxy myoglobin so pretty easy. It translates directly over to my globe. Now the same goes for the K. D as well the dissociation equilibrium constant which is of course, going to be the ratio of the products over the reactant. And of course, for the dissociation going backwards, the product is going to be P NL free p and l. And so essentially, when we translate this over to myoglobin, the free p in the free l are just gonna be m B and 02 so we can add that in here and B and 02 And then, of course, the protein ligand complexes just going to be M B 02 oxygenated Hema globe myoglobin. Now, of course, the ratio of the rate constant is gonna be the same. And of course, we also know that the K D is the reciprocal of the K A. And so again, this information that we learned in our previous videos applies directly. And we can really do the same thing for the fractional saturation as well, where we can simply just substitute the variable. So, of course, the pl here protein leg in complex is gonna be M B Same for down here is going to be M B 02 And then, of course, the free protein right here is just going to be my global. And then, of course, the lie again for myoglobin is going to be oxygen. 02 And here we also have oxygen. And so essentially what we're doing is we're taking everything that we learned from our previous lesson videos, and we're applying it directly to my global and so we could get some practice utilizing, uh, this new application of our previous concepts to in our next practice video. So I'll see you guys there.

So now that we've covered myoglobin is protein like and interactions In this video, we're going to focus on hemoglobin protein, like an interactions which are actually just a bit mawr complicated than myoglobin, simply because of the fact that hemoglobin has, um, or complex structure. And so recall that myoglobin is not an Alice Derek protein because it only has one single sub unit, whereas hemoglobin, on the other hand, is an Alice derek protein with multiple sub units, each of which combined a lie gang of oxygen. And so notice down below. Here in our image, we're showing you hemoglobin protein leg in interaction. And so, just to be able to generalize this and apply this to other Alice Derek proteins to, we're gonna use the variable end here to represent the number of ligand binding sites instead of putting a four here for four oxygen's and so notice. Here we have d oxy hemoglobin, and that is representing our protein. And so the oxygen gas molecule there is going to be an end number of oxygen gas molecules, depending on the number of ligand binding sites. And so here we have four oxygen gas molecules that we can see. And once all of those bind here to hemoglobin, we can get Oxy hemoglobin. And so it will have four of these oxygen's bound once all of them are bound. And so we will put again an end here to represent the number of ligand binding sites. And so what I want you guys to recall from way, way back in our older lesson videos is that whenever we have coefficients in a reaction and recall it, coefficients are just numbers in front of a molecule. Kind of like how we have a number here in front of this 02 We have to include these coefficients, uh, into the equilibrium, constant as exponents. And so recall that literally the dissociation equilibrium constant is an equilibrium constant itself. And so what that means is we need to be able to include this coefficient of n here as an exponents. And so any time we have the lie Gand all by itself, we need to include it as an exponents. And so here where we have the k d notice that we have the lie again all by itself. So we need to include and here as the exponents And then, of course, now are protein like and complex has changed in a way where it has the end here as the subscript. So we need to include that as well. And so here, over here for the fractional saturation weaken include end here in the protein leg in complex as the subscript. And of course, for the, um, lie again all by itself, it will be included as an exponents here. And so really, this is how human global's protein leg in interactions differ from myoglobin simply by taking the coefficients of the reaction and including them as exponents. And really, that's the main difference. And so, as we move forward in our course will be able to get mawr and mawr practice applying all of these concepts, and we'll also learn more and more about hemoglobin and myoglobin. So I'll see you guys in our next video

in this video, we're just going to give you guys some more background information about hemoglobin. And so it's important to know that hemoglobin is actually found within red blood cells and red blood cells can be abbreviated with RBC for short. And the technical name is a re throw site. And so a re throw site and red blood cells as well as RBC are all synonyms of one another. And so again, the hemoglobin molecules are found inside of the red blood cells. And so if we take a look down below at our image down below, it helps give us a little bit of context of where we can find these hemoglobin molecules. So over here, what we have is an image of the heem group that we know. Um, the hemoglobin molecule contains. And so we know that hemoglobin has four of these heem groups that really look like alien disk shape structures. And so, of course, this is going to represent the hemoglobin molecule. Now again, the hemoglobin molecules are found inside of the red blood cells, so they're gonna be found on the inside of these a re throw sites, which again is a synonym for red blood cells. And then, of course, inside, uh, these red blood cells are going to be found within the blood stream. And, uh, basically to give you guys a little bit of context on the numbers here. So, um, each individual red blood cell has approximately 270 million molecules of hemoglobin, and that is an immense amount of hemoglobin molecules inside of just one single red blood cell. Now, also, one drop of blood the size of a pinhead, which is very, very small has about five million red blood cells. And so, if we were to calculate how many hemoglobin molecules are in a drop of blood the size of a pinhead, all we would need to do is take the five million red blood cells. So the five million red blood cells and multiply this bye the 270 million. So the 270 million hemoglobin molecules, uh uh, in just one red blood cell. And so when we do this, we get the red blood cell units to cancel out, and we can take this five million and multiply it by 270 million. And the units are gonna be in hemoglobin. And when we do that, what we get is a number that is incredibly massive, that I'll write down here. And it is 1.35 times 10 to the 15th hemoglobin molecules. And so this number here is actually 1.35 quadrillion hemoglobin molecules and just one single drop of blood the size of a pinhead. So this is a massive, massive number, and that just gives you guys a little bit of context of how much hemoglobin is found within a red blood cell and within our bodies. And so this year, uh, concludes our background information of hemoglobin and well again, we'll be able to learn a lot more about hemoglobin as we move forward in our course. So see you guys in our next video.

in this video, we're going to do a quick recap of some of the similarities and differences between myoglobin and hemoglobin. And so we're going to fill out this table down below and notice that in this first row right here, what we have is myoglobin and of course, myoglobin is abbreviated with M B now down below. In this bottom row notice what we have is hemoglobin. And of course, hemoglobin is abbreviated with H B. Now, in order to fill out this first row right here, what we need to figure out is the number of sub units and recall that myoglobin on Lee has one single poly peptide chain, which means that myoglobin only has one single sub unit and because it only has one single sub unit, myoglobin is not an al hysteric protein, whereas hemoglobin, on the other hand, notice has four separate poly peptide chains, which means that hemoglobin has four sub units and hemoglobin has to Alfa sub units and two beta subunits. And that's what composes these four sub units and also recall that hemoglobin is an aloe starik protein. Now, in terms of the number of him groups, we can visually see that myoglobin on Lee has won him group, which is this alien disc shaped structure right here, This UFO structure And because it only has one him group, we can put one over here. So it has one team group for its one sub unit. And of course, him a global, on the other hand, actually has four team groups, one for each of its four sub units. And so we can put over here that it also has four team groups. Now, myoglobin is going to be located specifically in muscle tissues. And we'll talk more about this idea later in our course, whereas hemoglobin, on the other hand, we said in our previous lesson, video is gonna be found within red blood cells in the bloodstream, so I'll abbreviate red blood cells with RBC s And then, of course, in terms of reversible e binding oxygen, both myoglobin and hemoglobin can reversible e bind oxygen. And that's because they both have him groups. And really, it's these heem groups that are responsible for the ability to reverse Aly bind oxygen and because again, both myoglobin and hemoglobin have him groups. They can both reversible bind oxygen and we'll be able to talk more about this ability to bind reversible, bind oxygen, uh, later in our course. But for now, this concludes the recap of my global versus hemoglobin, and I'll see you guys in our next video.