Reverse Reaction ofAspergillus nigerAPC-9319 α-Galactosidase in a Supersaturated Substrate Solution: Production of α-Linked Galactooligosaccharide (α-GOS)
The cell walls of an acapsular strain of the yeast Cryptococcus laurentii catalyze the regioselective formation of alpha-galactooligosaccharides through self-condensation of 4-nitrophenyl alpha-D-galactopyranoside and of a novel activated ot-galactosyl donor 2,2,2-trifluoroethyl of-o-galactopyranoside. The latter substance can be easily prepared by several methods and is highly soluble in water and therefore can be used in higher initial concentrations suppressing secondary product hydrolysis. The preparative reaction catalyzed by cell walls provided 17.4% and 2% of corresponding 2,2,2-trifluoroethyl galactobioside and galactotrioside, respectively, while the reaction with 4-nitrophenyl alpha-D-galactopyranoside provided the corresponding 4-nitrophenyl galactobioside and galactotrioside in 6.6 and 2.5% yields, respectively. The reactions proceeded with strict alpha-(1 -> 6)-regioselectivity. (C) 2017 Elsevier Ltd. All rights reserved.
The acid-labile, peripheral chains of the mucilage of Opuntia ficus-indica