This is not the usual form in which the equation is used. Instead, the equation is set to zero, meaning , indicating we are at equilibrium and the concentrations  and  are now equilibrium concentrations, hence:
Rearranging this gives the so-called Haldane relationship:
The advantage of this is that one of the four constants can be eliminated and replaced with the equilibrium constant which is more likely to be known. In addition, it allows one to make a useful interpretation in terms of the thermodynamic and saturation effects (see next section). Most often the reverse maximum rate is eliminated to yield the final equation: