Zhang Ningning, Lahmann Viktoria, Bittner Jan Philipp, Domínguez de María Pablo, Jakobtorweihen Sven, Smirnova Irina, Kara Selin
Institute of Technical Chemistry, Leibniz University Hannover, Callinstr. 5, 30167, Hannover, Germany.
Institute of Thermal Separation Processes, Hamburg University of Technology, Eißendorfer Straße 38, 21073, Hamburg, Germany.
ChemSusChem. 2025 Mar 15;18(6):e202402075. doi: 10.1002/cssc.202402075. Epub 2024 Nov 19.
Redox biocatalysis is an essential pillar of the chemical industry. Yet, the enzymes' nature restricts most reactions to aqueous conditions, where the limited substrate solubility leads to unsustainable diluted biotranformations. Non-aqueous media represent a strategic solution to conduct intensified biocatalytic routes. Deep eutectic solvents (DESs) are designable solvents that can be customized to meet specific application needs. Within the large design space of combining DES components (and ratios), hydrophobic DESs hold the potential to be both enzyme-compatible - keeping the enzymes' hydration -, and solubilizers for hydrophobic reactants. We explored two hydrophobic DESs, lidocaine/oleic acid, and lidocaine/decanoic acid, as reaction media for carbonyl reduction catalyzed by horse liver alcohol dehydrogenase, focusing on the effect of water contents and on maximizing substrate loadings. Enzymes remained highly active and stable in the DESs with 20 wt % buffer, whereas the reaction performance in DESs outperformed the pure buffer system with hydrophobic substrates (e. g., cinnamaldehyde to form the industrially relevant cinnamyl alcohol), with a 3-fold specific activity. Notably, the cinnamaldehyde reduction was for the first time performed at 800 mM (~100 g L) with full conversion, which opens up new avenues to industrial applications of hydrophobic DESs for enzyme catalysis.
氧化还原生物催化是化学工业的重要支柱。然而，酶的性质将大多数反应限制在水相条件下，在此条件下，有限的底物溶解度会导致不可持续的稀释生物转化。非水介质是实现强化生物催化途径的一种策略性解决方案。深共熔溶剂（DESs）是可设计的溶剂，可以根据特定应用需求进行定制。在组合DES成分（及比例）的广阔设计空间内，疏水性DESs既有潜力与酶兼容——保持酶的水合作用，又能作为疏水性反应物的增溶剂。我们研究了两种疏水性DESs，利多卡因/油酸和利多卡因/癸酸，作为马肝醇脱氢酶催化羰基还原反应的介质，重点关注含水量的影响以及使底物负载量最大化。在含有20 wt%缓冲液的DESs中，酶保持了高活性和稳定性，而在DESs中的反应性能优于使用疏水性底物的纯缓冲液体系（例如，肉桂醛转化为具有工业相关性的肉桂醇），比活性提高了3倍。值得注意的是，肉桂醛还原反应首次在800 mM（约100 g/L）下进行且完全转化，这为疏水性DESs在酶催化工业应用方面开辟了新途径。
