Fig. 3. The pH dependence of R[H2O]/[E] (ms 1)
catalyzed by wild type HCA III ( ), K64H
HCA III ( ), R67H HCA
III ( ), and
the double mutant K64H/R67H HCA III ( circle ).
The values were determined by 18O exchange at 25 °C using
solutions containing no buffers; ionic strength of solution was
maintained at 0.2 M by addition of NaSO. The lines are
least squares fits of Equation 6 to the data yielding the values
of pK[a] of the donor and acceptor groups and the values of k[B]
given in Table IV.
The above figure is reprinted
by permission from the ASBMB:
J Biol Chem