title: Acylation of soluble polysaccharides in a biphasic system catalyzed by a CE2 acetyl esterase.
abstract: Within the last decade, acylated polysaccharides have drawn attention, since they find applications in numerous fields as biocompatible and biodegradable amphiphilic compounds. The ability of a CE2 acetyl esterase from Clostridium thermocellum to catalyze acyl transfer to β-glucan and manno-polysaccharides of significant interest was investigated. Initially, screening tests were conducted on aldohexose monosaccharides and disaccharides, exploiting the enzyme's strict regioselectivity at O-6 position. Modified monosaccharides acquired acylation yields from 11 up to 65%, showing preference for small chain acyl donors, while disaccharides exhibited conversion yields from 23 up to 58%, with preference to monoacylation. The transesterification reactions were carried out in two-phase mixtures consisted of water/vinyl esters. Acylation of polysaccharides were confirmed by TLC and FT-IR, while the degree of acylation was determined via an indirect method, estimating a range of acylation from 0.022 to 1.083mmolacylgroup*gpolysaccharide-1depending on the structure and composition of the target polysaccharide.
authors.affiliation: IndBioCat Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, 5 Iroon Polytechniou Str., Zografou Campus, Athens 15780, Greece.
authors.forename: Maria
authors.initials: M
authors.lastname: Kanelli
authors.affiliation: IndBioCat Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, 5 Iroon Polytechniou Str., Zografou Campus, Athens 15780, Greece. Electronic address: vtopakas@chemeng.ntua.gr.
authors.forename: Evangelos
authors.initials: E
authors.lastname: Topakas
mesh_terms: D000115:Acetylesterase / Q000378:metabolism*; D000215:Acylation; D048013:Acetivibrio thermocellus / Q000201:enzymology; D004951:Esterification; D009005:Monosaccharides / Q000737:chemistry; D011134:Polysaccharides / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D009005:Monosaccharides; D011134:Polysaccharides; D000115:Acetylesterase
keywords: Acylated polysaccharides; CE2 acetyl esterase; Clostridium thermocellum; Regioselectivity; Transesterification