Synergy Between an .ALPHA.-L-Arabinofuranosidase from Aspergillus oryzae and an Endo-Arabinanase from Streptomyces coelicolor for Degradation of Arabinan

Abstract

An α-L-arabinofuranosidase gene of Aspergillus oryzae was expressed in Pichia pastoris. The re-combinant enzyme released L-arabinose from arabinose-containing polysaccharides such as lupin pectic galactan, corn hull arabinoxylan, sugar beet arabinan, and potato pectic galactan. The enzyme displayed an optimum activity at 45°C and pH 4.0. The enzyme was slowly inactivated above pH 6.0 and below pH 3.0, and was stable at temperatures up to 40°C. On the other hand, a putative endo-arabinanase gene of Strep-tomyces coelicolor was cloned and expressed in Escherichia coli. The recombinant enzyme hydrolyzed linear arabinans and produced α-1,5-arabinooligosaccharides. The enzyme displayed an optimum activity at 45°C and pH 6.0. The enzyme was slowly inactivated above pH 10.0 and below pH 4.0, and it was stable at temperatures up to 35°C. Synergisms between the α-L-arabinofuranosidase and the endo-arabinanase for the degradation of arabinan and debranched arabinan were observed. The hydrolysis was most efficient when α-L-arabinofuranosidase and endo-arabinanase were in a ratio of 95 : 5.