So, if we examine the s one pocket of Elastanes, we'll see the presence of two additional Valene and valine, if you recall, are these small or valine molecules, have these small, relatively small hydrophobic chains. And notice where these two valleys are positions, they're positioned opposite of each other and they essentially play the role of blocking the majority of the bottom portion of that s one pocket. And so what that means is when the side chain group of the amino acid moves into the s one pocket, it cannot actually occupy this space here because this blocks, as a result of the stair kindle of the hydrophobic properties of these side chain groups. And so only those amino acids that have relatively small side chain groups and which are nonpolar so uncharged, will be able to fit into this pocket. And so we see that Elastase cleaves peptide bonds on the carboxyl end of small hydrophobic amino acids such as glycine, vallene, Alanine, Valine, Alanine Leucine and Isolucine, as well as serene. So if we have this hypothetical polypeptide chain, we have glycine, lysine, Alanine, phenylalanine, glycine.