Fluorescence-activated cell sorting and directed evolution of α-N-acetylgalactosaminidases using a quenched activity-based probe (qABP).

An α-N-acetylgalactosamine-containing quenched activity-based probe (qABP) was designed and successfully synthesized, and it was subsequently used in directed enzyme evolution experiments aided by fluorescence-activated cell sorting (FACS) for the discovery of an α-N-acetylgalactosaminidase variant with improved catalytic activity.