But in this case, only one has to be bound for that reaction to actually take place. And in fact, the two substrates bind and are catalyzed at different times inside the active side of the enzyme that follow these double displacement reactions. So to see what we mean, let's take a look at the following general case. So in these reactions, the first substrate binds and changes the enzyme to produce an enzyme substrate intermediate complex. And this can be seen in the following diagram. So let's suppose we have substrate A that binds onto the active side of the enzyme to produce this intermediate.