Biotransamination of Furan-Based Aldehydes with Isopropylamine: Enzyme Screening and pH Influence

<p>Furan-based amines are highly valuable compounds which can be directly obtained via reductive amination from easily accessible furfural, 5-(hydroxymethyl)furfural (HMF) and 2,5-diformylfuran (DFF). Herein the biocatalytic amination of these carbonyl derivatives is disclosed using amine transaminases (ATAs) and isopropylamine (IPA) as amine donors. Among the different biocatalysts tested, the ones from <i>Chromobacterium violaceum</i> (Cv-TA), <i>Arthrobacter citreus</i> (ArS-TA), and variants from <i>Arthrobacter</i> sp. (ArRmut11-TA) and <i>Vibrio fluvialis</i> (Vf-mut-TA), afforded high levels of product formation (&gt;80 %) at 100–200 mM aldehyde concentration. The transformations were studied in terms of enzyme and IPA loading. The pH influence was found as a key factor and attributed to the imine/aldehyde equilibrium that can arise from the high reactivity of the carbonyl substrates with a nucleophilic amine such as IPA.</p>