Enzymatic method of producing 4-0-beta-D galactopyranosyl-D-xylose, 4-0-beta-D-galactopyranosyl-D-xylose obtained using said method, compositions containing same and the use thereof in evaluating intestinal lactase

摘要

In the preparation of 4-O-beta -D-galactopyranosyl-D-xylose (I) by reacting D-xylose, a beta -galactopyranoside substrate and beta -D-galactosidase (BDG) in aqueous buffer, (I) is isolated (after deactivating or removing the BDG and removing the substrate aglycone) by adding celite, carrying out solid-liquid extraction and eluting from a column, and (I)-containing fractions are treated by crystallization. Preparation of 4-O-beta -D-galactopyranosyl-D-xylose (I) involves: (i) treating a mixture of 2-20 wt.% D-xylose, 0.5-5 wt.% of a beta -galactopyranoside (as substrate) and 75-97.5 wt.% aqueous buffer of pH 5.0-9.0 (as reaction medium) with 10-1000 U (per g of substrate) of beta -D-galactosidase (BDG); (ii) carrying out disaccharide-forming reaction at a temperature between the freezing point of the mixture and 45[deg]C for 2-48 hours; (iii) deactivating the BDG by freezing at -20 to -170[deg]C or by heating at 95-115[deg]C or removing the BDG from the mixture by ultrafiltration; (iv) removing the aglycone of the substrate by extraction or filtration, and (v) isolating the (I)-containing fractions. Step (v) is carried out by adding celite, carrying out solid-liquid extraction with a solvent and eluting from a column with a first eluant, or by directly adding activated carbon, filtering and eluting with a second solvent. The (I)-containing fractions are further treated by crystallization from a mixture of acetone and methanol (or water) in a ratio of 5-20:1. An independent claim is included for (I) obtained by the process.