Blood Tolerant Laccase by Directed Evolution

High-redox potential laccases are powerful biocatalysts with a wide range of applications in biotechnology. We have converted a thermostable laccase from a white-rot fungus into a blood tolerant laccase. Adapting the fitness of this laccase to the specific composition of human blood (above neutral pH, high chloride concentration) required several generations of directed evolution in a surrogate complex blood medium. Our evolved laccase was tested in both human plasma and blood, displaying catalytic activity while retaining a high redox potential at the T1 copper site. Mutations introduced in the second coordination sphere of the T1 site shifted the pH activity profile and drastically reduced the inhibitory effect of chloride. This proof of concept that laccases can be adapted to function in extreme conditions opens an array of opportunities for implantable nanobiodevices, chemical syntheses, and detoxification.
This study was based upon work funded by EU Projects (NMP4-SL-2009-229255-3D-Nanobiodevice, FP7-KBBE-2010-4-26537-Peroxicats and COST Action CM0701) and a project from the Spanish Government (BIO2010-19697). D.M.M. was supported by a JAE grant and D.G.P. was supported by a Peroxicats contract. M.P. received support from the 2009 Ramón y Cajal programme of the Spanish MINECO.