How do we find this information? So this is what we're going to look at in this lecture. So we're going to begin by assuming we know what our protein is. So let's suppose we have a six amino acid polypeptide. So we have alanine, arginine, phenylalanine, glycine, aspartate, and glycine. Now, of course, usually you don't know what that protein actually is, but in this lecture, I give you the composition of that protein to basically show you how this method actually works.