Bradykinin, a peptide that helps to regulate blood pressure, has the primary structure Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg.
b. Bradykinin has a very kinked secondary structure. Why?

Question

Bradykinin, a peptide that helps to regulate blood pressure, has the primary structure Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg.

b. Bradykinin has a very kinked secondary structure. Why?

Accepted Answer

Welcome everybody. Let's look at our next question. A protein has the primary structure. T hr H ISP rotyr pr ol eu pr O pr oglut hr which amino acid is responsible for its very kinked helix secondary structure. A tyrbl Eu ct hr or D pr O. Well, I'm just going to quickly jot down the full names of these amino acids as we talk about them. Tyr racine lau lucine T hr three anine N Pr O prolene. So let's think about these amino acids and what might lead to this very kinked secondary structure by kinks in a structure. You would mean bends so many bends in the structure. So let's think about the characteristics of these amino acids. I might jump quickly to choice D Prolene because I can see there are quite a number, there are 1234, there's four prolene residues that will have an effect on the structure. And when I think about prolene, it's got that very unusual structure where the R group is a ring that binds back on itself, binds to the backbone nitrogen atom of the structure. So if I draw the structure of prolene, I have that NH two my alpha carbon. So ch carbon carbon as in oh and the R group, which I'll draw here in red is a three carbon chain that is a ring joined to that nitrogen. So I actually have to erase the hydrogen here. It's just NH in this case to make room for that bond. And I have this five atom ring connecting the alpha carbon to the nitrogen there. So this has two effects. One, this is a very rigid ring. It's only a five member ring. So there's not much flexibility in this. So every time it occurs in the structure, you'll have this prevention of it from moving and you have this looping back around. And the other thing is extremely significant when we think about the usual alpha helix, what causes that helix to have its shape is hydrogen bonding between the carbonyl carb oxygens, excuse me, carbonyl oxygen atoms and the amid hydrogen atoms. But let's look back at this Prolene. What happens with it when it's involved in a peptide bond? Well, well, imagine here's the carbonyl group of the a prior amino acid forming a peptide bond with our prolene. So I'll put the nitrogen there. I'm gonna highlight that peptide von in blue. Well, I have to lose that single nitrogen. Remember there's only one nitrogen in that backbone because the chain itself is binding to it. So when the peptide bond forms, that nitrogen loses its lone hydrogen and I just have this nitrogen bound to the carbon, alpha carbon there. Continue on our little structure here. And then my R group chained oops wrong place between the nitrogen and the alpha carbon. But what happens here, there is no amid hydrogen every time there's a prole. So for every pr in the structure, no hydrogen bond is possible. So that will interfere with any alpha heli structure or beta sheets. And you'll have these rigid rings causing these bends in the structure and you can't have your regular loops of your alpha helix. So Prolene is definitely going to be our culprit here. We can take a quick look at our other amino acids to remind ourselves of what they are. Or tyro I have that's ch two bonded to a benzene ring. Draw my little ring there with an oh group for lucine, I have CH two C two and then CH three and a little methyl group on there s that in the wrong place. And then for three anine, I have a C CH three with an oh as well on that ch. But you can see that compared to that ring doubling back and binding to the backbone atom, none of these are going to interfere with a structure so much as prolene. So that's why none of those A B or C are going to be our culprit. Our amino acid that's going to cause a very kinky secondary structure is choice D Prolene see you in the next video.

Bradykinin, a peptide that helps to regulate blood pressure, has the primary structure Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg.
b. Bradykinin has a very kinked secondary structure. Why?

Verified video answer for a similar problem:

Key Concepts

Primary Structure of Proteins

Secondary Structure of Proteins

Role of Proline in Protein Structure

Bradykinin, a peptide that helps to regulate blood pressure, has the primary structure Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg.b. Bradykinin has a very kinked secondary structure. Why?

Verified video answer for a similar problem:

Key Concepts

Primary Structure of Proteins

Secondary Structure of Proteins

Role of Proline in Protein Structure

Bradykinin, a peptide that helps to regulate blood pressure, has the primary structure Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg.
b. Bradykinin has a very kinked secondary structure. Why?