Highest paraoxonase turnover rate found in a bacterial phosphotriesterase variant.

The bacterial phosphotriesterase (PTE) catalyses the hydrolysis of the man-made pesticide paraoxon with a diffusion-limited efficiency. Here we describe the selection and characterisation of PTE variant SS0.2 that possesses the highest paraoxonase turnover number so far described (k(cat) = 31,000 s⁻¹). The PTE-SS0.2 was selected from a library of binding-site mutants using a novel screening method that combines partial lysis of bacterial colonies and fluorogenic probes.