Enhancement of the GD Catalytic Activity of the OPH Enzyme by ProteinEngineering: Screening and Kinetic Analysis of Two Mutants

摘要

The enzyme organophosphate hydrolase (OPH) catalyzes the hydrolysis of several G-type nerve agents. The enzyme has relatively high levels of activity with DFP, GB. and GF but much less activity with GD. In these studies, different site-specific OPH mutants were tested for their activity levels on DFP and GD. Two mutants, 257L and 257V, were found to have 43-fold and 29-fold increased levels of GD activity, respectively. Kinetic analyses (Vmax and Km) of these mutants were conducted using GD as the substrate. A profile of activity versus pH was also completed for 257L. This is the first report of the successful enhancement of G-agent enzymatic activity through protein engineering.