Positional specifity of acetylxylan esterases on natural polysaccharide: An NMR study

► 1H-NMR signals of the acetyl groups in hardwood acetyglucuronoxylan were assigned. ► The assignment enabled study of the action of acetyxylan esterases on natural substrate. ► Mode of action of Streptomyces lividans and Orpinomyces sp. enzymes (CE4 vs. CE6) was elucidated. ► The results are important in view of further progress of bioconversion of plant biomass.