Authors: Harivony Rakotoarivonina Beatrice Hermant Brigitte Chabbert JeanPierre Touzel Caroline Remond
Publish Date: 2011/01/29
Volume: 90, Issue: 2, Pages: 541-552
Abstract
A gene Txest1 encoding a thermostable feruloylesterase was isolated from the genome of the Grampositive hemicellulolytic thermophilic bacterium Thermobacillus xylanilyticus This gene contains an open reading frame of 1020 bp encoding a protein with molecular mass of 374 kDa similar to feruloylesterases from cellulolytic bacteria and fungi The recombinant enzyme TxEst1 was expressed and produced in Escherichia coli TxEst1 contains the conserved putative lipase residues Ser 202 Asp 287 and His 322 which act as catalytic triad in its Cterminus part Purified TxEst1 was active against phenolic acid derivatives and stable at high temperatures Optimal activity was observed at 65 °C and the optimal pH was around 85 The kinetic parameters of the esterase were determined on various substrates The enzyme displayed activity against methyl esters of hydrocinnamic acids and feruloylated arabinoxylotetraose exhibiting high specificity and affinity for the latter Our results showed that TxEst1 is a thermostable feruloylesterase which could be useful to hydrolyze arabinoxylans from graminaceous plant cell walls as the enzyme is able to release phenolic acids from a lignocellulose biomass
Keywords: