What we have to do is we have to expose that polypeptide chain to proteolytic molecules that cleave our peptide at specific locations. So we essentially cut up and divide this long fragment, this long polypeptide chain, into many small fragments. And then we take each one of these fragments and we run egman degradation on each one of these fragments. And that allows us to basically determine exactly what that sequence is of each one of these fragments. And then we repeat the process with a different proteolytic enzyme. And eventually we can basically find what the order is of these different fragments in that polypeptide chain.