Mechanistic kinetic modelling of enzyme-catalysed oxidation reactions of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA)

Six enzymes were tested against HMF and its oxidation intermediates to determine substrate specificity, product yield and pathways. A Michaelis–Menten kinetic mathematical model was constructed and some rate parameters calculated. The best 2,5-diformylfuran (DFF) productivity was obtained with alcohol oxidase (AO) and 10.0 mM HMF, where 3.0 mM DFF was formed, followed by galactose oxidase (GO) and 10.0 mM HMF with a 0.5 mM DFF yield. Oxygen concentration in solution remained unchanged during processes. Substrate concentration affected only AO, where around 10 mol.% more DFF was formed with 5.0 mM HMF. The model was mostly in good agreement with single-enzyme reactions. Multi-enzyme reactions were used for model validation. The combination of AO and catalase was optimal, converting 10.0 mM HMF to 9.7 mM DFF. Small discrepancy between measured and modeled multi-enzyme reactions was observed due to the exclusion of the specific interactions in mechanisms.