Figure 9: There are three stages in the dynamics of the MM reaction mechanism (1) when e₀ < s₀ and K_M ≈ 0.

The red arrows demarcate the approximate path of a typical trajectory during each stage. Stage one is the fast transient: the trajectory rapidly approaches the curve c = e₀, and the duration of this stage is roughly $t_C^{\ast }$. During the second stage, the trajectory closely follows the curve c = e₀; the duration of this stage is roughly t_ℓ. The final stage corresponds to the the rQSSA, as the trajectory follows the curve c = s₀ − p. The timescale corresponding to stage three is t_slow = 1/k₂. If $t_C^{\ast }\ll t_{\ell }\ll 1∕k_2$, then the rQSSA is at least heuristically valid.