It contains a high enough electron density around the oxygen as to actually attack nucleophilically this carbon of this peptide bond. And so once the carbon is attacked, that displaces the pi bond and places those two electrons that were initially in the pi bond onto this oxygen. So the serine alcohol acts as a nucleotide and attacks the carbon of the carbonyl. And what we ultimately form after step one is we form a tetrahedral intermediate. So in this particular case, if we examine this bond here, we see that we have SP two hybridization. And what that means is this is going to be a planar molecule and that gives this molecule stability.