And what happens is we have these two substrate molecules, the ATP is our A and the Creatine is our B. And notice in this particular reaction, because we're dealing with a random sequential reaction, the order at which these two reactors, the two substrates, actually bind onto the active side does not matter. We can either have the ATP bind first, followed by the creatine, or we can have the creatine bind first followed by the ATP. But because this is a sequential reaction, just like in the order sequential reaction case, we have to actually form that ternary structure, that structure that contains the enzyme bound to the two substrate molecules, in this case ATP and creatine. Only when we form this three molecule complex can we begin the process of catalyzation. And only now can we transform the ATP into the ATP and the Creatine into the phosphorine.