Testing Electrostatic Complementarity in Enzyme Catalysis: Hydrogen Bonding in the Ketosteroid Isomerase Oxyanion Hole
Figure 5
Potential Catalytic Contribution from a Greater Strengthening of Hydrogen Bonds Accompanying Charge Redistribution in an Enzymatic Environment than in Aqueous Solution
As charge increases on the carbonyl oxygen going from the ground state to the transition state, hydrogen bonds from either water or an enzyme tyrosine will strengthen. Results from small molecule studies indicate that in a nonaqueous environment such as an enzyme active site, this strengthening (ΔΔGE) can be greater than in aqueous solution (ΔΔGsoln), where little strengthening is observed [68, 151, 152]. This potential differential strengthening is indicated by the different sizes of hydrogen-bonded dots and the larger change in ΔG between the ground state and the transition state for the enzymatic reaction compared with the solution reaction. Adapted from [68].