Aspartame, which is commonly known as NutraSweet™, contains the following dipeptide:
d. Draw the structure of the isomer of this dipeptide where the C-terminal and N-terminal amino acids are switched.

Question

Aspartame, which is commonly known as NutraSweet™, contains the following dipeptide:

Structure of a dipeptide with switched C-terminal and N-terminal amino acids, featuring aspartame components.

d. Draw the structure of the isomer of this dipeptide where the C-terminal and N-terminal amino acids are switched.

Accepted Answer

All right. Hello everyone. So this question says Arnaz, a dipeptide present in human muscles consists of two specific amino acids. And here the structure is actually given to us illustrate the structure of the isomer where the N terminal and C terminal amino acids have been swapped. So the good news is that peptides should be written in the same way. And this is because a convention exists where a peptide is drawn from the N terminus to the C terminus going from left to right. So what does that mean? What do I mean when I say N terminus and C terminus? Well, let's consider the structure of Carine that we're given. Looking over here to the structure of carnine. We can see that the N terminus is the amino acid on the left side that has the free amino group here it's pronated. So it's NH three positive. So similarly, if we go on the right side, we can see that the C terminus is the amino acid that has the free carboxyl group farthest to the right. So when it comes to drawing out the isomer, the backbone should be the same, right? Because peptide chains should be written in the same fashion. The difference is swapping the order of these amino acids. So on the left side, we can see that after the carbon carbon, we have two ch twos followed by the pronated amino group. This if you recall is characteristic of beta alanine. So that's our first amino acid. Now, our second amino acid has a side chain here that has the ametazole ring characteristic of histidine. So that's her second amino acid. Let me actually write his on the top. So for the isomer, the idea is just to swap where histidine and beta alanine are located. So let's start with the backbone, right? We're going to start with our proton and amino group. But this time histidine is supposed to be the n terminal amino acid. So we have one alpha carbon where the side chain is connected, followed by the carbo carbon this time. However, because the carbon carbon is inside the peptide chain, it's going to make up the peptide bond between itself and the amino group of our second amino acid. And so now that I've drawn the nitrogen, we are now going to go ahead and draw the structure of beta ay. So after the amino group, that's two ch twos followed by our carboxyl group or a free carboxylate group, just move this off to the side for clarity. And now because we already completed the structure of beta alanine, all that's left is to finish the structure of histidine by adding that ametazole side change. So now we have one more ch two and our ametazole ring fix the ring a little bit. It looked uneven for a second and there you have it. And so now we have our completed isomer. So here the amino acids used are the exact same. But the difference now is that histidine is the n terminal amino acid on the farthest left. And beta alanine is our c terminal amino acid farthest to the right. And so with that being said, thank you so very much for watching. And I hope you found this helpful.

Aspartame, which is commonly known as NutraSweet™, contains the following dipeptide:

d. Draw the structure of the isomer of this dipeptide where the C-terminal and N-terminal amino acids are switched.

Verified video answer for a similar problem:

Key Concepts

Dipeptides

Isomerism

Amino Acid Structure