Measuring PETase enzyme kinetics by single-molecule microscopy.

Plastic pollution is a global environmental and human health problem. PETases are recently discovered enzymes that degrade the ubiquitous plastic polyethylene terephthalate (PET). A push is underway to understand and optimize these enzymes to enable large-scale microplastics remediation. Here, we use single-molecule fluorescence microscopy to visualize the interactions of PETase enzyme molecules with a thin film of PET. We identify specific binding interactions of a few seconds that differ between wild-type and PETase mutants that have been previously shown to have altered activities. These single-molecule investigations provide a new window into the mechanism and activity of PETase enzymes, and provide a platform for characterizing and optimizing novel PETases with improved function and stability.