title: Purification and characterization of a thermostable α-galactosidase from Thielavia terrestris NRRL 8126 in solid state fermentation.
abstract: Several seeds and husks of some plants belonging to leguminosae, Graminae, Compositae and Palmae were evaluated as carbon substrates to produce α-galactosidase (α-Gal) by the thermophilic fungus, Thielavia terrestris NRRL 8126 in solid substrate fermentation. The results showed that Cicer arietinum (chick pea seed) was the best substrate for α-Gal production. The crude enzyme was precipitated by ammonium sulphate (60%) and purified by gel filtration on sephadex G-100 followed by ion exchange chromatography on DEAE-Cellulose. The final purification fold of the enzyme was 30.42. The temperature and pH optima of purified α-Gal from Thielavia terrestris were 70 °C and 6.5, respectively. The enzyme showed high thermal stability at 70 °C and 75 °C and the half-life of the α-Gal at 90 °C was 45 min. Km of the purified enzyme was 1.31 mM. The purified enzyme was inhibited by Ag2+, Hg2+, Zn2+, Ba2+, Mg2+, Mn2+ and Fe2+ at 5 mM and 10 mM. Also, EDTA, sodium arsenate, L-cysteine and iodoacetate inhibited the enzyme activity. On the other hand, Ca2+, Cu2+, K+ and Na+ slightly enhanced the enzyme activity at 5 mM while at 10 mM they caused inhibition. The molecular weight of the α-Gal was estimated to be 82 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This enzyme displays a number of biochemical properties that make it a potentially strong candidate for biotechnological and medicinal applications.
authors.affiliation: Biological & Geological Sciences Department, Faculty of Education Ain Shams University, Heliopolis, Roxy, Cairo Egypt.
authors.forename: Rawia R
authors.initials: RR
authors.lastname: Saad
authors.forename: Eman M
authors.initials: EM
authors.lastname: Fawzi
mesh_terms: D001203:Ascomycota / Q000201:enzymology*; D002850:Chromatography, Gel / Q000379:methods; D002852:Chromatography, Ion Exchange / Q000379:methods; D029863:Cicer / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D004791:Enzyme Inhibitors / Q000378:metabolism; D004795:Enzyme Stability; D005285:Fermentation; D005656:Fungal Proteins / Q000302:isolation & purification* / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D013696:Temperature; D000519:alpha-Galactosidase / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D005656:Fungal Proteins; D000519:alpha-Galactosidase