Fig. 2.

Fluorescence transients of BmorPBP upon changing the pH. (A) The time dependence of the basic to acidic (B → A) conformational change is fitted by one exponential term to generate the observed rate constant (k) (reduced χ², 1.95). (B) The time course of the reverse reaction (A → B) was fitted by two-exponential terms (k₁ and k₂). Note the faster step followed by a second, slower process (reduced χ², 0.59). (Inset) A steep increase in fluorescence intensity in the first 150 ms of the reaction is shown.