Functional characterization of starch-degrading enzymes using quartz crystal microbalance with dissipation monitoring (QCM-D)

During the last few decades, starch-degrading enzymes have emerged as promising tools for transforming biomass. Nevertheless, their functional characterization, based essentially on colorimetric tests, is still fastidious and time-consuming. In order to overcome these hurdles, we have developed a test for real-time and label-free detection of starch-degrading enzymes using quartz crystal microbalance with dissipation monitoring (QCM-D). By starch-functionalization of surfaces, we were able to discriminate clearly enzymes with different hydrolysis patterns (endo versus exo). The variation of the hydrolytic activity between the wild-type and a mutant of a cyclodextrin glucosyl transferases could also be monitored acoustically. The high sensitivity reached (down to 6.5 nkat/L) opens the prospect of using fewer enzyme quantities for functional tests and is a further advantage for this easily used and efficient tool for enzyme characterization.