The thick black curve is the numerically-integrated solutions to the mass action equations (49a)–(49d). The dashed vertical line corresponds to tc2 Note that there is no significant increase in the concentration of the intermediate complex over the tc2 timescale. The constants (without units) used in the numerical simulation are: , , , k1 = 1, k2 = 1, k3 = 1, k−3 = 1, k4 = 100 and k−1 = 1. Time has been mapped to the t∞ scale: t∞(t) = 1 — 1/ln[t + exp(1)], and c2 has been scaled its maximum value.