Kinetic Analysis of a Series of Phosphotriesterase Mutants with Respect to Sarin and Soman Catalysis

摘要

A series of site-directed mutants of the organophosphorus-hydrolyzing enzyme phosphotriesterase (PTE) were analyzed with respect to their kinetics on the G-agent substrates sarin (GB) and soman (GD). Values of Km, Vmax, and Kcat/K m were compared with the wild-type values. Several mutants were found with decreased Km values on both substrates, although all had at least somewhat decreased Vmax values as well. The K cat/Km calculations showed two mutants (G6OA and H254G/H257R) with GB catalytic efficiencies nearly as high as wild- type. With respect to GD catalytic efficiency, both these mutants were in the same Kcat/Km range or higher than wild-type. In addition to their potential practical utility for decontamination, these results also provide part of the roadmap for future mutagenesis studies with the PTE enzyme.