Fig. 10.

A nonequilibrium steady-state flux can be imposed on this two bridge rate mechanism (top) by either (A) making the last step irreversible, as is usually done, or (B) recasting in terms of a closed loop. In (B), the four state mechanism becomes a cyclical three state mechanism, from which the nonequilibrium steady-state flux is easily obtained without invoking irreversibility. Detailed balance dictates that $k_{\text{L}}^{\to }{k}_{1\to 2}{k}_{\text{R}}^{\to }=k_{\text{R}}^{\leftarrow }{k}_{2\to 1}{k}_{\text{L}}^{\leftarrow }$ when Δμ_RL = 0.