Inhibition of Zea mays coniferyl aldehyde dehydrogenase by daidzin: A potential approach for the investigation of lignocellulose recalcitrance

Abstract

Coniferyl aldehyde dehydrogenase (CALDH) catalyzes the oxidation of coniferyl aldehyde to ferulic acid. Because ferulic acid has a relevant role in the structure and recalcitrance of the cell wall, inhibition of CALDH can reduce its levels and increase the digestibility of lignocellulosic biomass. We prospected in silico a selective inhibitor of CALDH of Zea mays. The ZmaysCALDH gene was identified by homology with the corresponding gene of Arabidopsis thaliana. The sequence was translated and analyzed, and the quaternary structure was modeled. A set of 20 putative inhibitors were screened from a virtual library and docked in the active site of ZmaysCALDH, and daidzin (DZN) was selected as an enzyme inhibitor. The stability of the ZmaysCALDH–DZN complex was evaluated by molecular dynamics simulations of the monomeric and tetrameric forms. For evaluation of kinetic analysis, ZmaysCALDH activity was determined in vitro by high-performance liquid chromatography. In comparison to the DZN-free control, the data obtained indicated constant Vmax and enhanced Km. Altogether, in silico and in vitro findings indicated that DZN inhibited ZmaysCALDH competitively. The DZN-induced inhibition of ZmaysCALDH could be a valuable and promising approach to studies on ferulic acid biosynthesis and saccharification of lignocellulosic biomass.