The rate equation for the second-order reaction of an enzyme (e) and its substrate (s) is vo = keat le][s] near the where it is the second-order rate constant, which can be used to compare catalytic efficiencies. enzymes with a diffusion-controlled limit are said to have achieved catalytic perfection. what is the diffusion-controlled limit in an aqueous solution? 10-4 to 10-8 m-s-1 107 to 10% m s 10 to 10-sm 109 to 1010 m.5-1 o 10-7 to 10-'m-'s-1 10% to 10º m/s o 10% to 10% m-1-1