2021 Annual Meeting
Transaminase Screening for Biocatalytic Functionalization of Polymer Plastic Waste
Exploring enzymatic routes in order to generate high value monomers or polymers offers an opportunity for recovery and diversification of plastic waste. Transaminases (TAs) are a class of enzymes that reversibly convert an aldehyde or ketone to an amine. These enzymes are well categorized for pharmaceutical applications, and this work aims to introduce these enzymes into pathways for plastic valorization centered around terephthalic acid (TPA) derived from depolymerized polyethylene terephthalate (PET). In this project, thirty transaminases were selected for screening and twenty-three were successfully expressed in the E. coli ROAR strain. Qualitative colorimetric assays along with quantitative high performance liquid chromatography (HPLC) analysis were used to track TA activity on various substrates. Two library members of previously uncharacterized TAs showed activity on a model substrate, benzaldehyde, and will be the basis of subsequent testing and comparison to previously characterized TAs. Substrate evaluation involved testing three derivatives of terephthalate (TPA), with IPA as the amine donor. Six total TAs were tested, and it was shown that Chromobacterium violaceum (C.v) and Vibrio fluvialis (V.f), had activity on plastic derivatives, paving the way for future plastic functionalization work. Continued bioprospecting involving this library will allow for the discovery of substrate specificity, thermal tolerance, and solvent tolerance for TAs with potential to create diamine monomers for high value, recyclable plastics.