Catalytic Rate Constant (kcat)
25 mM sodium phosphate
The data were collected with a Perkin-Elmer Lambda 25 spectrophotometer (Perkin-Elmer Italia, Monza, Italy). Steady-state kinetic analyses were performed under initial-rate conditions using the Hanes plot linearization method. For Km values of ≤10 μM, the Km values were determined as Ki values, using nitrocefin as the reporter substrate. Each kinetic value is the mean of five different measurements; errors were <5%.