A novel Ca²⁺-activated, thermostabilized polyesterase capable of hydrolyzing polyethylene terephthalate from Saccharomonospora viridis AHK190.Only two polyethylene glycol terephthalate (PET)-degrading enzymes have been reported, and their mechanism for the biochemical degradation of PET remains unclear.  To identify a novel PET-degrading enzyme, a putative cutinase gene (cut190) was cloned from the thermophile Saccharomonospora viridis AHK190 and expressed in Escherichia coli Rosetta-gami B (DE3).  Mutational analysis indicated that substitution of Ser226 with Pro and Arg228 with Ser yielded the highest activity and thermostability.  The Ca(2+) ion enhanced the enzyme activity and thermostability of the wild-type and mutant Cut190.  Furthermore, the enzyme degraded the PET film above 60 °C. 
THERM