And in the form we have it now, it will not be good enough nuclear file to attack that peptide bond. And so what must happen is the histidine and the aspartate must work together to transform this serine into a strong nuclear file. So what we essentially want to do is transform the alcohol into its conjugate base, valcoxide. 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.