Engineering DszC Mutants from Transition State Macrodipole Considerations and Evolutionary Sequence Analysis

We describe an approach to identify enzyme mutants with
increased
turnover using the enzyme DszC as a case study. Our approach is based
on recalculating the barriers of alanine mutants through single-point
energy calculations at the hybrid QM/MM level in the wild-type reactant
and transition state geometries. We analyze the difference in the
electron density between the reactant and transition state to identify
sites/residues where electrostatic interactions stabilize the transition
state over the reactants. We also assess the insertion of a unit probe
charge to identify positions in which the introduction of charged
residues lowers the barrier.