Michaelis Menten enzyme kinetics
A subclass of RSreac implementing Michaelis-Menten enzyme kinetics. This is a simplification of the scheme: A + enzyme <--> A-enzyme <--> B + enzyme. Such a scheme would normally require four rate constants, for the forward and backward parts of each transition. However, to a good approximation in many cases this can be reduced to two: k-m, the enzyme concentration at which the rate A --> B is half maximal and v-max, the maximum rate when the enzyme concentration is so high that the A + enzyme <--> A-enzyme equilibrium is almost completely to the right.
Assuming the return from B + enzyme --> A-enzyme to be negligible, this still requires one more parameter which is here taken as the ratio of kr, the dissociation rate of A-enzyme, to v-max, k-r-by-v-max.
The importance of the M-M expression is that in modeling actual reactions the behavior of the schemes is often insensitive to the value of k-r-by-v-max which may change by an order of magnitude from Unity with little apparent effect.