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. So we have a partial positive charge here because the oxygen contains a partial negative charge. And so by the same analogy here when the nitrogen pulls away the H it gives the electrons to the sulfur and so the electron density on the sulfur increases and it becomes a better nucleophile. Here when the negative charge the oxygen pulls away the H, it makes the oxygen a better nucleophile because we essentially transform water into a hydroxide and the hydroxide is a much stronger nucleophile.