Enzymatic Synthesis of High Molecular Alcohol β-Xylosides by the Transfer Reaction of β-Xylosidase in The Presence of Alcohol

Abstract

Among several fungal β-xylosidases, Aspergillus niger β-xylosidase had the highest hydrolytic activity and stability in the presence of water miscible solvents such as acetone and alcohols. The enzymatic synthesis of alkyl β-xylosides from xylobiose and alcohols through the transxylosylation reaction of the enzyme was studied. Various alkyl β-xylosides were effectively synthesized from xylobiose and water miscible alcohol such as methanol, ethanol and 2-propanol. Water immiscible alcohol such as 1-butanol, 1-hexanol, benzyl alcohol and 2-butanol, also acted as effective acceptors for transxylosyl reaction, where a great part of synthesized β-xylosides were found in the insoluble alcohol layer. Therefore, the synthesized β-xyloside, such as l-hexyl β-xyloside, could be readily separated from the reaction mixture and crystallized. Xylooligomers and xylan hydrolyzates acted as an effective xylosyl donor . Accumulation factors of alkyl β-xyloside produced enzymatically in the transxylosylation and superiority of Asp, nigerβ-xylosidase for the enzymatic synthesis of alkyl β-xylosides were also described.