title: Purification and properties of a beta-galactosidase with potential application as a digestive supplement.
abstract: Functional-based screening of crude beta-galactosidase activities from 42 yeast strains resulted in the selection of a single enzyme of potential interest as a digestive supplement. beta-Galactosidase produced by Kluyveromyces marxianus DSM5418 was purified to homogeneity by a combination of gel filtration, ion-exchange, and hydroxylapatite chromatographies. The denatured (123 kDa) and native molecular masses (251 kDa) suggest that the enzyme is a homodimer. The optimum pH and temperature of the purified enzyme were 6.8 and 37 degrees C, respectively. The unpurified beta-galactosidase in particular displayed a high level of stability when exposed to simulated intestinal conditions in vitro for 4 h. Matrix-assisted laser desorption ionization mass sectrometry analysis revealed that the enzyme's trypsin-generated peptide mass fingerprint shares several peptide fragment hits with beta-galactosidases from Kluyveromyces lactis. This confirms the enzyme's identity and indicates that significant sequence homology exists between these enzymes.
authors.affiliation: Department of Chemical and Environmental Sciences and MSSI, University of Limerick, Limerick City, Ireland.
authors.forename: S
authors.initials: S
authors.lastname: O'Connell
authors.forename: G
authors.initials: G
authors.lastname: Walsh
mesh_terms: D019587:Dietary Supplements; D004789:Enzyme Activation; D004795:Enzyme Stability; D005765:Gastrointestinal Agents / Q000737:chemistry*; D007716:Kluyveromyces / Q000145:classification* / Q000201:enzymology*; D013045:Species Specificity; D001616:beta-Galactosidase / Q000737:chemistry* / Q000302:isolation & purification*
chemical_list: D005765:Gastrointestinal Agents; D001616:beta-Galactosidase