Fig. 3.

Stabilization of a reaction intermediate by mutation G262S. Reaction of BcII WT and G262S with nitrocefin, measured by using a photodiode array detector in a stopped-flow system under single-turnover conditions. All spectra are shown until the reaction completion time. The absorbance changes at 390 (S), 490 (P), and 665 (EI) nm are indicated with arrows. Nitrocefin hydrolysis by WT BcII proceeds by direct conversion of S to P (Left). The G262S mutation stabilizes the anionic intermediate EI (Right), depicted in the reaction scheme.