In today's video we're going to be discussing myoglobin. In the previous video we were talking about hemoglobin, so this is kind of similar, they have different functions, but they're both heme proteins, so let's just go into it in a bit more detail. So, myoglobin is a heme protein which is present in heart.
and skeletal muscle. So myoglobin is present in cardiac and skeletal muscle and its function is to act as an oxygen carrier that increases the rate of transport of oxygen within the muscle cell and it acts as a reservoir for oxygen. So its main function is to increase the amount of oxygen within the muscle itself and this is highly important during periods of exercise where the muscles require extra oxygen.
for respiration. And its structure. Now, myoglobin is a very compact molecule. There are eight alpha helices which are present within the structure of myoglobin. And if you don't know what an alpha helix is, it's where, if you can imagine a sequence of amino acids, so it's in its secondary structure, that along the backbone of...
of the molecule, there are nitrogens from the amino part of the amino acid, and there's a carbonyl group. So how it works is the nitrogen donates a hydrogen to the carbonyl group along the backbone. So what this means is it helps to form a spiral.
So this is what an alpha helix is. And within myoglobin, there are eight of these alpha helixes which are folded to together in a loop and you can label each of the alpha helixes from A all the way until H. So the first one is A, the second one is B, the third one is C and so on. And another thing to note is the interior of myoglobin consists of non-polar or hydrophobic amino acids and the surface of myoglobin consists of polar and hydrophobic amino acids.
amino acids and this is quite similar to hemoglobin as well so the inside consists of water hating amino acids and the outside consists of water loving amino acids so this helps it to form to react with solvents basically now finally just to finish off the video we're going to talk about the binding of the heme group so how it actually is stable within the myoglobin structure, the heme part. So there are two residues which help to bind the heme group. So there's the proximal histidine residue, which binds directly to the ion of heme, and there's the distal histidine.
And what this does is it helps to stabilize the binding of oxygen to the ion itself. Now that's the video today on myoglobin. The next video will be discussing the oxygen.
oxygen dissociation curves of myoglobin and hemoglobin. And thanks for watching. If you've got any questions, write them below. Thanks.