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The development of an efficient screening method for the activity of PET-degrading enzymes represents a significant technological advance in the field of enzyme research, with the potential to facilitate the advancement of enzymes for PET recycling. By examining the stable conditions of PET suspension and enzyme production conditions, we developed a method to quantify PET-degrading enzyme activity in E. coli culture medium using turbidity reduction as an indicator. High PET concentration or ionic strength caused aggregation of PET, and the best condition for activity detection was 0.5 mg mL -1 PET in 50 mM sodium phosphate pH 7.0. Preculture of E. coli increased the purity of enzyme secreted in medium. To evaluate the screening method, 720 colonies of the PET2-7M-H229X-F233X mutant library were analyzed and three candidates of high-activity mutants were obtained. The thermostability of the mutants could also be easily measured by measuring the residual activity after heat treatment. The H229T-F233M mutant showed 3.4 times higher degradation rate against PET film than the template enzyme at the initial time. The molecular dynamics simulation implied that the F233M mutation makes space for making an α helix and that the H229T mutation resolved the steric hindrance with Trp199. These mutations were speculated to change the angle of the Trp199 side chain of PET2 to an angle similar to that of the Trp185 of IsPETase, making it suitable for PET binding to the active center. Screening of activity using PET suspensions is compatible with robotic automation and is expected to be useful for validating computationally predicted mutations., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Background/aim: Recent lung cancer treatments include an immune checkpoint inhibitor (ICI) pembrolizumab, platinum-based agents, plus an additional cytotoxic anticancer agent. Nutritional indices, such as the geriatric nutritional risk index (GNRI) and the prognostic nutritional index (PNI), are known to correlate with the prognosis of cancer chemotherapy. Several previous studies have investigated the relationship between PNI and treatment response in non-small cell lung cancer patients, reporting significantly increased OS and PFS in the high PNI group before treatment. However, the relationship between the three-drug combination and GNRI/PNI is unclear. The current study aimed to investigate the association of nutritional indices with duration of treatment success and occurrence of side effects in triple therapy., Patients and Methods: Seventy-two patients with non-small cell lung cancer, treated with combination of carboplatin, pemetrexed, and pembrolizumab from November 2019 to September 30, 2022, were classified into two groups (High and Low) for GNRI and PNI, and a retrospective study was performed., Results: In terms of time-to-treatment-failure (TTF), univariate and multivariate Cox proportional hazards regression analysis showed the Low-PNI group to have significantly shorter TTF than the High-PNI group (p=0.006); multivariate analysis results also showed PNI as a factor affecting TTF (HR=2.791, 95%CI=1.362-5.721, p=0.005). On the other hand, GNRI was not shown to be a factor affecting TTF., Conclusion: PNI at the start of treatment was an independent prognostic factor affecting treatment success time (TTF) in non-small cell lung cancer patients receiving triple therapy. However, PNI was not shown to be a prognostic predictor of irAE development., (Copyright © 2024, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)