Professor Kyung-Jin Kim at Kyungpook National University, Daegu, South Korea.
A research team led by Professor Kyung-Jin Kim of Kyungpook National University has identified two new principles that determine the performance of PET-degrading enzymes, or PETases.
PET, or polyethylene terephthalate, is widely used in bottles, clothing, automotive interiors, food packaging, and agricultural produce containers. Biocatalytic recycling uses enzymes to break PET into raw materials that can be used again. Enzyme performance is central to the process because higher performance can reduce the amount of enzyme required, shorten reaction time, and directly lower processing costs.
Until now, enzyme engineering has largely focused on the catalytic region that directly cuts the plastic chain. Professor Kim's team demonstrated that the enzyme surface is also a critical factor.
First, the researchers found that the SEC-loop, a small protruding structure on the surface of CaPETase, interferes with the enzyme's access to PET. Reducing the protruding structure increased the degradation rate by up to 2.8 times. The result showed that performance depends not only on how much enzyme attaches to PET, but also on whether it makes contact at a productive angle. The same principle was confirmed across representative PET-degrading enzymes, including Kubu-P and LCC.
The team also adjusted the charge characteristics of the enzyme surface to address limitations in the reaction environment. Most high-performing PET-degrading enzymes operate under alkaline conditions, generally at pH 8 to 9. During degradation, however, the reaction solution becomes acidic, requiring continued addition of alkaline solution and increasing process costs and carbon emissions.
By changing the charge environment on the enzyme surface, the researchers removed electrostatic repulsion with the PET surface under alkaline conditions and secured an enzyme-design approach that maintains high activity across a broader pH range.
The findings suggest that improving enzyme surfaces can provide a new strategy for reducing the cost and carbon burden of biocatalytic recycling. The principles may be applied to multiple degrading enzymes, including Kubu-PM12, which Professor Kim's team previously discovered and improved.
ZyEn Co., Ltd., a subsidiary of Kyungpook National University Technology Holdings led by Professor Kim, is conducting proof-of-concept research to verify the commercialization potential of biocatalytic recycling.
Commercial Application in Agricultural Packaging
With the authorization of ZyEn and GemPack Berries, Reborn Materials Inc. is adding a commercial application pathway to the university's scientific announcement. Reborn is working to connect ZyEn's enzyme platform with sustainable materials, traceability, recovery, recycling, and measurable ESG systems.
Through its relationship with GemPack Berries, a major North American berry and agricultural operating platform, Reborn is exploring how the technology may be evaluated within high-volume produce packaging and distribution. Agricultural operations use substantial volumes of PET clamshell packaging, providing a practical environment for future evaluation across production, distribution, collection, material identification, recycling, and verification.
“These studies show that the structure and charge of the enzyme surface, which have received little attention, can determine plastic-degradation performance,” Professor Kim said. “By adding the enzyme surface to the catalytic site as a new design strategy, we will make it a reality to revive plastics faster and more economically with less enzyme.”
“This is where science must meet real operating volume,” said Jason W. Kang, Chief Operating Officer of Reborn Materials Inc. “ZyEn provides the scientific platform, GemPack provides the agricultural operating environment, and Reborn connects materials, recovery, traceability, and commercial execution.”
The related studies were published in Nature Communications and the Journal of Hazardous Materials in 2026. The research was supported by programs of the National Research Foundation of Korea, the Korea Institute for Advancement of Technology, and the Ministry of Trade, Industry and Energy.
Research Publications
• Mechanistic insights into modulation of productive substrate accessibility for efficient PET depolymerization: https://doi.org/10.1038/s41467-026-74839-7
• Effect of surface electrostatic potential on pH-activity profile in PET depolymerases: https://doi.org/10.1016/j.jhazmat.2026.142179