Draw a dipeptide structure consisting of given amino acids in the following order. Next, we have to name the dipeptide using the three-letter codes separated by hyphens. Alright. So here, remember, we have to write this in terms of N terminus to C terminus. This means that the amino acid on the left side will have its carboxyl group interacting with the amino group of the amino acid on the right. This is a condensation reaction where we're going to have the loss of water. So, we're going to lose the oxygen from the carboxyl group and two hydrogens from the amino group. This is where water is being lost. After that, everything left behind will come together to form our dipeptide structure.
We have our benzene ring with an OH group connected to this CH2, which is connected to this carbon with the NH3+. Next, we have our carboxyl group. Here, I'm going to draw the peptide bond in red. It's connected now to this nitrogen, which still has one of its hydrogens. It's still connected to all this stuff here. So CH2, and then we have SH here, and then we have the carboxyl group here. So this will be our dipeptide structure.
Now what we need to do is we need to basically give the three-letter code. So if we take a look at this, this amino acid on the right is easy to spot because it has an SH group which is unique to cysteine. We know cysteine's three-letter code is Cys, based on its first three letters. This one here has an OH group, it is a polar group, so remember this one is tyrosine. Its three-letter code is Tyr, again based on its first three letters. So that means that this dipeptide that we have here would be Tyr-Cys. So this would be the dipeptide name using our three-letter code. And this would be the dipeptide structure.