Improvement in the hydrolysis rate (specific activity) of chlorpyrifos by organophosphorous hydrolase (OPH) variant over wildtype OPH

Value 725 Fold
Organism Bacteria Escherichia coli
Reference Cho CM, Mulchandani A, Chen W. Altering the substrate specificity of organophosphorus hydrolase for enhanced hydrolysis of chlorpyrifos. Appl Environ Microbiol. 2004 Aug70(8):4681-5. Table - link PubMed ID15294802
Method Directed evolution. Researchers used two rounds of DNA shuffling and screened about 12,000 mutants to improve the hydrolytic activity of an organophosphorus hydrolase (OPH) 725-fold toward the toxin chlorpyrifos.
Comments The best variant (B3651) displayed a 725-fold increase in catalytic efficiency, and the measured kcat/Km value of 2.2×10^8M^-1s^-1 is similar to the reported value for hydrolysis of paraoxon by the wild-type OPH (9.9×10^7M^-1s^-1, Griffiths et al 2003, PMID 12505981), close to the diffusion-controlled limit of enzymatic reaction rate, see BNID 103 916, 105 087.
Entered by Uri M
ID 105434