Direct measurement of PET hydrolase interfacial kinetics reveals catalysis-independent surface remodelling
How PET hydrolases engage solid plastic has been inferred almost entirely from soluble analogs and surfactant-stabilised nanoparticle suspensions, and reported affinities span orders of magnitude. Here we measure it directly, depositing thin amorphous PET films onto gold surface plasmon resonance chips and following enzyme binding to authentic polymer in real time. Four PET hydrolases, LCC,…
Scientists have directly measured the kinetics of enzymes interacting with plastic, revealing a surface remodeling process separate from catalysis. By depositing thin films of polyethylene terephthalate (PET) onto gold sensors and monitoring real-time enzyme binding, researchers analyzed four PET-degrading enzymes with nanomolar affinity and tens of minutes residence times.
One enzyme, LCC-ICCG, showed a dissociation rate within two-fold of its catalytic rate constant, suggesting turnover limitation is due to detachment rather than ester hydrolysis. The study found non-monophasic responses during enzyme association, including signal declines even when the enzyme remained on the surface. This decline persisted in an inactive enzyme variant and was absent in control proteins and a non-plastic-degrading enzyme, indicating non-catalytic surface changes.
The rate of surface remodeling varied among enzymes on the same film, was inhibited by Triton X-100, and was influenced by PET degradation products, revealing a catalysis-independent chain-mobilisation step crucial for PET depolymerisation that soluble assays cannot detect.
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