Directly mining and identifying a cellobiose 2-epimerase with isomerization activity by phylogenetic analysis

Abstract

The isomerization activity of cellobiose 2-epimerase (CE) offers the potential for conversion of lactose into lactulose. However, the isomerization activity of reported CEs is low and identifying CE with isomerization activity is still challenging and time consuming. Here, we developed a strategy for directly mining CE with isomerization activity through phylogeny analysis and a novel CE from Dictyoglomus sp (XVH1-CE) was identified which has isomerization activity as expected. The isomerization activity of XVH1-CE could reach 4.3 U mg−1 at 85 °C and pH 7.5, which is highest among all reported CEs. Moreover, Molecular Dynamics (MD) simulation further revealed that XVH1-CE presents a significant region change influenced by lactulose, and statistic special binding pose seen as important for lactulose catalysis performed a high frequency. Our research demonstrated enzyme-mining strategy based on phylogeny analysis can offers new opportunities for the development of lactulose production by CE.