ABSTRACT
In the search for useful and renewable chemical building blocks, 5-hydroxymethylfurfural (HMF) has emerged as a very promising candidate, as it can be prepared from sugars. HMF can be oxidized to 2,5-furandicarboxylic acid (FDCA), which is used as a substitute for petroleum-based terephthalate in polymer production. On the basis of a recently identified bacterial degradation pathway for HMF, candidate genes responsible for selective HMF oxidation have been identified. Heterologous expression of a protein from
Methylovorus
sp. strain MP688 in
Escherichia coli
and subsequent enzyme characterization showed that the respective gene indeed encodes an efficient HMF oxidase (HMFO). HMFO is a flavin adenine dinucleotide-containing oxidase and belongs to the glucose-methanol-choline-type flavoprotein oxidase family. Intriguingly, the activity of HMFO is not restricted to HMF, as it is active with a wide range of aromatic primary alcohols and aldehydes. The enzyme was shown to be relatively thermostable and active over a broad pH range. This makes HMFO a promising oxidative biocatalyst that can be used for the production of FDCA from HMF, a reaction involving both alcohol and aldehyde oxidations.
摘要
在寻找有用的可再生化学砌块的过程中,5-羟甲基糠醛(HMF)成为一种非常有前途的候选物质,因为它可以从糖类中制备出来。HMF 可氧化成 2,5-呋喃二甲酸(FDCA),后者在聚合物生产中可替代石油基对苯二甲酸盐。根据最近确定的 HMF 细菌降解途径,确定了负责选择性 HMF 氧化的候选基因。异源表达来自
Methylovorus
菌株 MP688 的蛋白质在
大肠杆菌
的蛋白质进行异源表达,随后进行酶鉴定,结果表明相关基因确实编码一种高效的 HMF 氧化酶(HMFO)。HMFO 是一种含黄素腺嘌呤二核苷酸的氧化酶,属于葡萄糖-甲醇-胆碱型黄素氧化酶家族。有趣的是,HMFO 的活性并不局限于 HMF,它对多种芳香伯醇和醛类也有活性。研究表明,这种酶具有较好的热稳定性,在较宽的 pH 值范围内都具有活性。这使得 HMFO 成为一种很有前景的氧化生物催化剂,可用于从 HMF 生产 FDCA(该反应涉及醇和醛的氧化)。