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A novel acid-stable, acid-active β-galactosidase potentially suited to the alleviation of lactose intolerance

O'Connell, Shane, Walsh, Gary
Applied microbiology and biotechnology 2010 v.86 no.2 pp. 517-524
Aspergillus niger, Kluyveromyces marxianus, beta-galactosidase, databases, digestive tract, filtration, gels, hydrophobic bonding, ion exchange, isoelectric point, lactose, lactose intolerance, molecular weight, pH, small intestine, stomach, temperature
Extracellular β-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 °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 β-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 β-galactosidase was formulated, along with a neutral β-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.