So in step one, we formed a relatively unstable tetrahedral intermediate. So we call it a tetrahedral because here we have one, two, three sigma bonds. And here the carbon has 1234 sigma bonds. Now, because of the instability of this intermediate, a special pocket, a special region on the Chimotryptin enzyme known as the oxyanion hole or oxyanine pocket, basically interacts with the negative charge on this oxygen. So inside the pocket we have these nitrogen atoms that contain H atoms. And these partially positive H atoms can interact with the fully negative oxygen atom.