It also includes tryptophan and tyrosine. So, if we take a look at the following hypothetical polypeptide chain that consists of seven amino acids, we have glycine, methionine, phenylalanine, tyrosine, alanine, tryptophan and glycine. And this is the corresponding threedimensional structure. Now, let's take any one of these amino acids. So let's suppose this amino acid here, and this happens to be the tyrosine because this is the side chain group of tyrosine. Now, this C carbon here is the central carbon atom.