And that's exactly what we mean by catalysis by proximity and orientation. What the active side does is it induces this change that brings these two substrate molecules in close proximity and arranges them in a proper orientation which basically decreases the energy of transition and it basically catalyzes the transfer of this phosphoryl group from ATP onto the NMP. In addition, because these two substrate molecules are essentially trapped in the active side, nothing else can actually come in because this entire lid domain closes off. And so other molecules, for example, water molecules, will not be able to enter the active side and that means the water molecules will not be able to hydrolyze this section. And so that will decrease the likelihood that any competing reaction will take place. Because remember, the problem is if we don't have the NMP kinase and these two molecules are in the presence of water, water will be very likely to actually hydrolyze and break this bond here.