Laccase catalyses phytophenol furanocyclic dimerization: Substrate specificity and diastereoselective process

Lacasse can transform phytophenol into furanocyclic dimers, including coumaran linkage dimer and 3,7-dioxabicyclo[3.3.0]octane linkage dimer. However, the substrate specificity and diastereoselective pro-cess remain unknown until now. The study therefore selected a series of monomeric phytophenol iso-mers or analogues as substrates to interact with laccase from Trametes versicolor (Lac TV). The prod-ucts were rapidly identified by ultra-performance liquid chromatography coupled with high-resolution mass-spectrometry. On this basis, 9 dimerization reactions were established for a systematical structure- function relationship analysis. Through analysis, it can be concluded that, phytophenol furanocyclic dimerization requires a specific substrate structure, i.e., a C = C bond sitting at the-OH para-position and also conjugating with the phenolic core. The coumaran linkage dimerization presents "7,8 diastereose-lectivity " character; while the 3,7-dioxabicyclo[3.3.0]octane linkage dimerization shows not only "7,8 di-astereoselectivity " character but also "cis-8H,8'H " character. The former character is attributed to the intramolecular nucleophilic addition which always prevents the Re-attack. The latter character however is caused by a substantial energy gap between normal envelop conformation and twist envelop con-formation. All these findings can help to efficiently utilize Lac TV tool for phytophenol biosynthesis in chemistry fields.(c) 2022 Elsevier B.V. All rights reserved.