title: Positional specifity of acetylxylan esterases on natural polysaccharide: an NMR study.
abstract: BACKGROUND
  Microbial degradation of acetylated plant hemicelluloses involves besides enzymes cleaving the glycosidic linkages also deacetylating enzymes. A detailed knowledge of the mode of action of these enzymes is important in view of the development of efficient bioconversion of plant materials that did not undergo alkaline pretreatment leading to hydrolysis of ester linkages.
  
  
  METHODS
  In this work deacetylation of hardwood acetylglucuronoxylan by acetylxylan esterases from Streptomyces lividans (carbohydrate esterase family 4) and Orpinomyces sp. (carbohydrate esterase family 6) was monitored by (1)H-NMR spectroscopy.
  
  
  RESULTS
  The (1)H-NMR resonances of all acetyl groups in the polysaccharide were fully assigned. The targets of both enzymes are 2- and 3-monoacetylated xylopyranosyl residues and, in the case of the Orpinomyces sp. enzyme, also the 2,3-di-O-acetylated xylopyranosyl residues. Both enzymes do not recognize as a substrate the 3-O-acetyl group on xylopyranosyl residues α-1,2-substituted with 4-O-methyl-d-glucuronic acid.
  
  
  CONCLUSIONS
  The (1)H-NMR spectroscopy approach to study positional and substrate specificity of AcXEs outlined in this work appears to be a simple way to characterize catalytic properties of enzymes belonging to various CE families.
  
  
  CONCLUSIONS
  The results contribute to development of efficient and environmentally friendly procedures for enzymatic degradation of plant biomass.
authors: Institute of Chemistry, Slovak Academy of Sciences, Bratislava, Slovakia.
authors: Iveta
authors: I
authors: Uhliariková
authors: Mária
authors: M
authors: Vršanská
authors: Barry V
authors: BV
authors: McCleary
authors: Peter
authors: P
authors: Biely
mesh_terms: D000115:Acetylesterase / Q000737:chemistry* / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001673:Biodegradation, Environmental; D005656:Fungal Proteins / Q000737:chemistry* / Q000378:metabolism; D020085:Neocallimastigales / Q000201:enzymology*; D019906:Nuclear Magnetic Resonance, Biomolecular; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism; D048170:Streptomyces lividans / Q000201:enzymology*; D013379:Substrate Specificity / Q000502:physiology; D014990:Xylans / Q000737:chemistry* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D005656:Fungal Proteins; D011134:Polysaccharides; D014990:Xylans; C038910:glucuronoxylan; C007916:hemicellulose; D000115:Acetylesterase; C081851:acetylxylan esterase