In this particular case we see that we're going to have residues that will transform the water into a better nuclear phile. Now if we examine the active side of aspir proteases we're going to find two residues. One of these residues will be aspartic acid and the other one will be aspartate. So this is basically the same thing as this but this is in the deprovinated state and this is in the proteinated state. So we have aspartate, we have aspartic acid. Now when water moves into the active side the negative charge on the aspartate will interact with a positive charge on one of the H atoms.