May 11, 2025
Assay for the Enzymatic Degradation of PET Beads
- Joao Vitor Molino1
- 1University of California, San Diego
Protocol Citation: Joao Vitor Molino 2025. Assay for the Enzymatic Degradation of PET Beads. protocols.io https://dx.doi.org/10.17504/protocols.io.bp2l6xp8klqe/v1
License: This is an open access protocol distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Protocol status: Working
We use this protocol and it's working
Created: November 20, 2023
Last Modified: May 11, 2025
Protocol Integer ID: 91224
Keywords: enzymatic degradation of pet bead, enzymatic activity on pet bead, enzymatic degradation, pet bead, assay, absorbance measurement, absorbance reading, enzymatic activity, degradation
Funders Acknowledgements:
US Department of Energy
Grant ID: DE-EE0009671
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Abstract
This assay focuses on assessing the enzymatic degradation of PET beads through absorbance measurements at 240nm. The primary goal is to quantify the enzymatic activity on PET beads by monitoring the release of BHET. This is achieved using a UV-transparent microplate, with absorbance readings specifically taken at 240nm.
Guidelines
Ensure the supernatant transfer is consistent in volume across all samples.
The enzyme and PET bead concentrations might need optimization based on the sensitivity of the assay and the activity of the enzyme.
A negative control with an inactivated enzyme can help determine the baseline of non-enzymatic degradation.
Adjustments to the protocol may be necessary based on specific experimental parameters, enzyme characteristics, or the sensitivity required for the assay.
Materials
PET plastic beads
1M Potassium phosphate buffer (pH 8)
Plastic-degrading enzyme solution
Thermocycler with a lid temperature set to 105°C
TECAN plate reader
Greiner Bio-One UV-Star 96-well Microplates (UV-transparent)
PCR tubes
Pipettes and pipette tips
Troubleshooting
Safety warnings
Follow standard laboratory safety protocols, especially when working with enzymes and potentially sharp plastic materials.
Wear appropriate personal protective equipment throughout the experiment.
Reaction Setup
In each PCR tube, add 30mg of PET plastic beads.
Add 100 µL of 1 Molarity (M) potassium phosphate buffer to the tubes
Add 100 µL of the enzyme solution to the tubes with PET beads to initiate the reaction. These constitute the test samples.
Prepare a blank control by adding 100 µL of buffer and 100 µL of enzyme solution into a PCR tube without PET beads.
Incubation
Place the PCR tubes in the thermocycler.
Set the thermocycler to 68 °C with the lid heated to 105 °C to prevent condensation. Incubate for 12 hours.
Sampling
Following the incubation period, briefly cool the PCR tubes to room temperature.
Centrifuge the tubes if necessary to ensure that the PET beads settle to the bottom.
Carefully transfer 100 µL of the supernatant from each tube into the corresponding wells of the UV-Star™ 96-well Microplate.
Absorbance measurement
Measure the absorbance of each well at 240 nm using the TECAN plate reader. Ensure to measure both the test samples and the blank control.
Data Analysis
Calculate the enzymatic activity by comparing the absorbance readings of the test samples with that of the blank control. The difference in absorbance is indicative of BHET release and, consequently, of PET degradation.