# Quasi-steady-state approximation

From BioUML platform

Description of the quasy-steady-state approximation method is done in the section "Quasi-Steady-State Analysis". Below we use the notation given there.

As an example consider the simplest enzyme reaction

which involves an enzyme *E* binding to a substrate *S* to form a complex *ES* and its dissociation into a product *P* and the enzyme *E*.

Let us find the conditions under which the concentration of the complex *ES* is quasi-stationary in time *t* = 0. To do this, we consider the expressions

which result in the following derivatives

Next, we find the formulas for *δt _{ES}* and

*r*:

_{ES}Thus, the complex *ES* is in quasi-steady state at *t* = 0 only when *δt _{ES}* << 1, i.e.