In myoglobin, about one-half of the 153 amino acids have nonpolar R groups.
a. Where would you expect those amino acids to be located in the tertiary structure?

Question

In myoglobin, about one-half of the 153 amino acids have nonpolar R groups.

a. Where would you expect those amino acids to be located in the tertiary structure?

Accepted Answer

All right. Hello everyone. So this question says in a membrane protein consisting of 180 amino acids, half of them have nonpolar R groups. Given the proteins role in a hydrophobic lipid bilayer. Where would these nonpolar amino acids most likely be located in the protein's tertiary structure? So first and foremost, let's talk about tertiary protein structure, right? Because if you recall, it's characterized by the interactions of amino acid side chains or R groups, these side chains interact with other side chains and stabilize the three dimensional structure that results. Now, proteins are very sensitive to their environment, right? Their structure is very closely correlated with their function. And so the idea is to have structural elements that fit not only their environment but their role in the cell or the organism in general. One of those factors that needs to be taken into consideration is the fact that the protein must blend with its environment. So here, let's say I have a hypothetical protein that I'm representing here with this oval and I'm surrounding it in a cell or rather the membrane in this case. So let's say this larger circle around my protein is part of the membrane, the membrane of course, is nonpolar because it's composed of that lipid bilayer. And so the idea is to have this protein that's going to reside inside of the membrane mesh well with its environment, right, we want this protein to mix well with the nonpolar environment of the membrane. And so the proteins rather the amino acids, excuse me, that are going to interact with the bilayer directly should have a similar polarity as the lipid bilayer itself, right? And so that's where the nonpolar R groups are going to be involved, right? Those nonpolar R groups have a similar polarity to the outside environment. In this case, the membrane. So therefore, these nonpolar or hydrophobic R groups or rather the proteins with the nonpolar R groups should be found on the exterior of the protein. Otherwise, right, if you had polar R groups inside or rather in the exterior of the protein, then that protein is not going to mesh well with the nonpolar environment, which can compromise its function. So we want the non polar R groups to be on the exterior of this protein and there you have it. So with that being said, thank you so very much for watching. And I hope you found this helpful.

In myoglobin, about one-half of the 153 amino acids have nonpolar R groups.
a. Where would you expect those amino acids to be located in the tertiary structure?

Verified video answer for a similar problem:

Key Concepts

Tertiary Structure of Proteins

Hydrophobic and Hydrophilic Interactions

Amino Acid Properties

In myoglobin, about one-half of the 153 amino acids have nonpolar R groups.a. Where would you expect those amino acids to be located in the tertiary structure?

Verified video answer for a similar problem:

Key Concepts

Tertiary Structure of Proteins

Hydrophobic and Hydrophilic Interactions

Amino Acid Properties

In myoglobin, about one-half of the 153 amino acids have nonpolar R groups.
a. Where would you expect those amino acids to be located in the tertiary structure?