Background 2,5-Furandicarboxylic acid (FDCA) is one of the top biomass-derived value-added chemicals. It can be produced from fructose and other C6 sugars via formation of 5-hydroxymethilfurfural (HMF) intermediate. Most of the chemical methods for FDCA production require harsh conditions, thus as an environmentally friendly alternative, an enzymatic conversion process can be applied. Results Commercially available horseradish peroxidase (HRP) and lignin peroxidase (LPO), alcohol (AO) and galactose oxidase (GO), catalase (CAT) and laccase (LAC) were tested against HMF, 2,5-diformylfuran (DFF), 5-hydroxymethyl-2-furoic acid (HMFA) and 5-formyl-2-furoic acid (FFA). Enzyme concentrations were determined based on the number of available active sites and reactions performed at atmospheric oxygen pressure. AO, GO, HRP and LPO were active against HMF, where LPO and HRP produced 0.6 and 0.7% of HMFA, and GO and AO produced 25.5 and 5.1% DFF, respectively. Most of the enzymes had only mild (3.2% yield or less) or no activity against DFF, HMFA and FFA, with only AO having a slightly higher activity against FFA with an FDCA yield of 11.6%. An effect of substrate concentration was measured only for AO, where 20 mM HMF resulted in 19.5% DFF and 5 mM HMF in 39.9% DFF, with a K m value of 14 mM. Some multi-enzyme reactions were also tested and the combination of AO and CAT proved most effective in converting over 97% HMF to DFF in 72 h. Conclusions Our study aimed at understanding the mechanism of conversion of bio-based HMF to FDCA by different selected enzymes. By understanding the reaction pathway, as well as substrate specificity and the effect of substrate concentration, we would be able to better optimize this process and obtain the best product yields in the future.

中文翻译：

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5-羟甲基糠醛 (HMF) 与空气的酶促转化反应为生物基 2,5-二甲酰基呋喃 (DFF) 和 2,5-呋喃二甲酸 (FDCA)：机理、途径和合成选择性。

背景 2,5-呋喃二甲酸 (FDCA) 是生物质衍生的高附加值化学品之一。它可以通过形成 5-羟基甲基糠醛 (HMF) 中间体由果糖和其他 C6 糖生产。大多数 FDCA 生产的化学方法都需要苛刻的条件，因此作为一种环保的替代方法，可以应用酶促转化工艺。结果 市售辣根过氧化物酶 (HRP) 和木质素过氧化物酶 (LPO)、酒精 (AO) 和半乳糖氧化酶 (GO)、过氧化氢酶 (CAT) 和漆酶 (LAC) 针对 HMF、2,5-二甲酰呋喃 (DFF)、5 -羟甲基-2-糠酸（HMFA）和5-甲酰基-2-糠酸（FFA）。基于可用活性位点的数量和在大气氧压力下进行的反应确定酶浓度。AO、GO、HRP 和 LPO 对 HMF 有效，其中 LPO 和 HRP 产生 0.6% 和 0.7% 的 HMFA，GO 和 AO 分别产生 25.5% 和 5.1% DFF。大多数酶对 DFF、HMFA 和 FFA 的活性只有轻微（3.2% 或更低）或没有活性，只有 AO 对 FFA 的活性略高，FDCA 产率为 11.6%。仅对 AO 测量了底物浓度的影响，其中 20 mM HMF 在 39.9% DFF 中产生 19.5% DFF 和 5 mM HMF，K m 值为 14 mM。还测试了一些多酶反应，证明 AO 和 CAT 的组合在 72 小时内将超过 97% 的 HMF 转化为 DFF 最有效。结论 我们的研究旨在了解不同选择的酶将生物基 HMF 转化为 FDCA 的机制。通过了解反应途径，以及底物特异性和底物浓度的影响，