And we'll discuss much in much more detail what chymatrypsin actually does inside the active side. Now let's move on to method number two catalysis by proximity and catalysis by orientation. So if we recall the collision theory from basic chemistry based on the collision theory, for a reaction to actually take place, what must happen? Well, first of all, those two substrate molecules that are about to react must actually collide. So they must collide, they must collide with enough energy and they must collide with the proper orientation. So only when the collision actually takes place with the proper orientation and with the right amount of energy do we actually form the product molecule.