And so the transition state of the protoporphine ring has to be bent in shape. So the transition state of the protoporphrin basically has a bent shape. So that means if we can somehow build a transition state analog that has the protoporphine with the bent shape, that means that type of molecule will be much more likely to bind into the active side of that particular enzyme, the ferrokeletate. So in fact, what we can do is we can methylate one of the nitrogen atoms in that ring. And by methylating this nitrogen that creates stere hindrance and that forces the bending of that protoporphin ring. And now that we have formed this transition state analog whose structure resembles the transition state structure in that particular catalytic process, we can now expose, we can use this molecule, this transition state analog, as an antigen, essentially expose it to a plasma cell.