title: A novel acid-stable, acid-active beta-galactosidase potentially suited to the alleviation of lactose intolerance.
abstract: Extracellular beta-galactosidase produced by a strain of Aspergillus niger van Tiegh was purified to homogeneity using a combination of gel filtration, ion-exchange, chromatofocusing, and hydrophobic interaction chromatographies. The enzyme displayed a temperature optimum of 65 degrees C and a low pH optimum of between 2.0 and 4.0. The monomeric glycosylated enzyme displayed a molecular mass of 129 kDa and an isoelectric point of 4.7. Protein database similarity searching using mass spectrometry-derived sequence data indicate that the enzyme shares homology with a previously sequenced A. niger beta-galactosidase. Unlike currently commercialised products, the enzyme displayed a high level of stability when exposed to simulated gastric conditions in vitro, retaining 68+/-2% of original activity levels. This acid-stable, acid-active beta-galactosidase was formulated, along with a neutral beta-galactosidase from Kluyveromyces marxianus DSM5418, in a novel two-segment capsule system designed to ensure delivery of enzymes of appropriate physicochemical properties to both stomach and small intestine. When subjected to simulated full digestive tract conditions, the twin lactase-containing capsule hydrolyzed, per unit activity, some 3.5-fold more lactose than did the commercial supplemental enzyme. The acid-stable, acid-active enzyme, along with the novel two-segment delivery system, may prove beneficial in the more effective treatment of lactose intolerance.
authors.affiliation: Shannon Applied Biotechnology Centre, IT Tralee, Tralee, Co.Kerry, Ireland.
authors.forename: Shane
authors.initials: S
authors.lastname: O'Connell
authors.forename: Gary
authors.initials: G
authors.lastname: Walsh
mesh_terms: D001234:Aspergillus niger / Q000201:enzymology*; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007525:Isoelectric Focusing; D007526:Isoelectric Point; D007716:Kluyveromyces / Q000201:enzymology; D007785:Lactose / Q000378:metabolism; D007787:Lactose Intolerance / Q000188:drug therapy; D013058:Mass Spectrometry; D008970:Molecular Weight; D001616:beta-Galactosidase / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins; D001616:beta-Galactosidase; D007785:Lactose