Because remember, alcoxide molecules, alcoxide ions have a much better ability to actually act as nucleophiles because they have a better electron density around that oxygen atom. So what happens is the negatively charged side chain of aspartate basically interacts with this partially positive hydrogen atom. So if we examine so where is the color red. So let's take red and blue. So if we examine the charge value on this hydrogen, because the nitrogen is more electronegative than the hydrogen, what that means is this H atom will bear a partial positive charge. And so these two side chains will basically interact.