Abstract
Poly(ethylene terephthalate) (PET) is one of the most widely applied synthetic polymers, but its hydrophobicity is challenging for many industrial applications. Biotechnological modification of PET surface can be achieved by PET hydrolyzing cutinases. In order to increase the adsorption towards their unnatural substrate, the enzymes are fused to carbohydrate-binding modules (CBMs) leading to enhanced activity. In this study, we identified novel PET binding CBMs and characterized the CBM-PET interplay. We developed a semi-quantitative method to detect CBMs bound to PET films. Screening of eight CBMs from diverse families for PET binding revealed one CBM that possesses a high affinity towards PET. Molecular dynamics (MD) simulations of the CBM–PET interface revealed tryptophan residues forming an aromatic triad on the peptide surface. Their interaction with phenyl rings of PET is stabilized by additional hydrogen bonds formed between amino acids close to the aromatic triad. Furthermore, the ratio of hydrophobic to polar contacts at the interface was identified as an important feature determining the strength of PET binding of CBMs. The interaction of CBM tryptophan residues with PET was confirmed experimentally by tryptophan quenching measurements after addition of PET nanoparticles to CBM. Our findings are useful for engineering PET hydrolyzing enzymes and may also find applications in functionalization of PET.
Highlights
In the last few decades, plastic has taken a central role in the modern consumer society
The selected peptides can be divided into two groups based on their size: (1) CBM2 and CBM5 peptides possess more than 40 residues and (2) CBM1 and CBM10 peptides comprise less than 30 amino acids
A low root-mean-square deviation (RMSD) is typically an indicator of a stable peptide structure. Another stability parameter is the radius of gyration (Rg) that correlates with the overall shape of a peptide
Summary
In the last few decades, plastic has taken a central role in the modern consumer society. Conventional techniques used to modify PET require the application of harsh chemicals like concentrated alkali or plasma treatments to introduce hydrophilic groups (Brueckner et al 2008; Tkavc et al 2013). These chemical and physical methods exhibit a number of disadvantages, as they are environmentally detrimental or lead to loss in weight and bulk properties of the polymer (Shukla et al 1997; Brueckner et al 2008; Pellis et al 2016)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
