Transxylosylation of β-xylosidase from aspergillus awamori K4

Abstract

β-Xylosidase from Aspergillus awamori K4 was purified. The optimum pH and temperature were around pH 4 and 70°C, and the molecular weight was estimated to be 117,000 on SDS-PAGE analysis. The enzyme has broad acceptor specificity in transxylosylation. Especially, its acceptor accessibility for sorbitol and mannitol of sugar alcohols were higher than that for monosaccharides. Trehalose was a much more effective acceptor than maltose and lactose of other disaccharides. In the reaction with 13–14% xylooligosaccharides (consisting of 3.4% xylose, 67.9% xylobiose, and 28.7% xylotriose) and 9–13% acceptors (sorbitol, mannitol, and trehalose), the amount of transfer products for each acceptor was 7–11% in 24 h. On 1H- and 13C-NMR analysis, main transfer products with sorbitol and mannitol were 6-O-β-xylosyl sorbitol (77.3%) and l(6)-O-β-xylosyl mannitol (73.7%), respectively. Two products with trehalose were 6 (6′)-O-β-xylosyl trehalose (52.1%) and 6,6′-O-β-di-xylosyl trehalose (47.9%). © 1997, Taylor & Francis Group, LLC. All rights reserved.