What type of interaction would you expect between the side chains of each of the following pairs of amino acids in the tertiary structure of a protein?
b. alanine and valine

Question

What type of interaction would you expect between the side chains of each of the following pairs of amino acids in the tertiary structure of a protein?

b. alanine and valine

Accepted Answer

All right, hello everyone. So this question is asking us what type of interaction would occur between the side chains of phenylalanine and tryptophan option A says Vander Waals forces. Option B says hydrogen bonding C says ionic bonding and D says hydrophobic interaction. So first of all, what is tertiary structure? Right? Like the question implies, right, the type of interaction that we're focusing on is between the side chains of these amino acids and that if you recall is characteristic of tertiary structure. So tertiary structure is characterized by interactions between amino acid side chains. And so because amino acids can be characterized in different ways depending on their side chains, multiple different interactions are possible. And so all of these interactions as a whole create a more complex three dimensional shape, which is the tertiary structure of a protein. So here the type of interaction that's going to happen between phenylalanine and tryptophan is entirely dependent on their side chains. Are they polar nonpolar, et cetera. So from here, it's worth mentioning if you recall that both phenylalanine and tryptophan are hydrophobic amino acids, they are nonpolar amino acids because their side chains contain very large nonpolar groups, specifically aromatic rings. So now what does this mean for the type of interaction that they're going to participate in? Right. Well, recall that these folding patterns tend to be very characteristic. For example, in your average cellular environment, right, the protein is going to be surrounded by an aqueous substance. So by a polar fluid, therefore, it's characteristic for these hydrophobic amino acids to cluster around the center of the protein and have hydrophilic amino acids surround the outside interacting directly with the fluid. So here in the center, we have our nonpolar amino acids away from the aqueous environment. And here on the outside we have the polar amino acids. And so the reason why this happens is because of a force called hydrophobic interaction, right, hydrophobic molecules will tend to cluster together. And so this means that our answer is going to be D in the multiple choice. So D is going to be our correct answer. It's a hydrophobic interaction. But just for the sake of completeness, I just want to point out why Van Der Waal's forces would be wrong. Now, vander walls forces technically occur between both polar and nonpolar molecules. But because it's such a transient and weak interaction, it's not going to be enough to really stabilize something like a protein in tertiary structure. It is simply not that powerful of an interaction and it's very, very temporary. So there you have it. And with that being said, thank you. So very much for watching. And I hope you found this helpful.

What type of interaction would you expect between the side chains of each of the following pairs of amino acids in the tertiary structure of a protein?
b. alanine and valine

Verified video answer for a similar problem:

Key Concepts

Amino Acid Side Chains

Hydrophobic Interactions

Tertiary Structure of Proteins

What type of interaction would you expect between the side chains of each of the following pairs of amino acids in the tertiary structure of a protein?b. alanine and valine

Verified video answer for a similar problem:

Key Concepts

Amino Acid Side Chains

Hydrophobic Interactions

Tertiary Structure of Proteins

What type of interaction would you expect between the side chains of each of the following pairs of amino acids in the tertiary structure of a protein?
b. alanine and valine