The rate equation for the second-order reaction of an enzyme (e) and its substrate (s) is = where is the second-order rate constant, which can be used to compare catalytic efficiencies. enzymes with a near the diffusion‑controlled limit are said to have achieved catalytic perfection. what is the diffusion‑controlled limit in an aqueous solution? 107 to 108 m⋅s 10−9 to 10−8 m−1s−1 10–6 to 10–5 m 108 to 109 m/s 109 to 1010 m⋅s−1 108 to 109 m−1s−1 10−7 to 10−9 m−1s−1