title: Purification and characterization of endo-beta-1,4 mannanase from Aspergillus niger gr for application in food processing industry.
abstract: A thermostable extracellular beta-mannanase from the culture supernatant of a fungus Aspergillus niger gr was purified to homogeneity. SDS-PAGE of the purified enzyme showed a single protein band of molecular mass 66 kDa. The beta- mannanase exhibited optimum catalytic activity at pH 5.5 and 55 degrees C. It was thermostable at 55 degrees C, and retained 50% activity after 6 h at 55 degrees C. The enzyme was stable at a pH range of 3.0 to 7.0. The metal ions Hg(2+), Cu(2+), and Ag(2+) inhibited complete enzyme activity. The inhibitors tested, EDTA, PMSF, and 1,10-phenanthroline, did not inhibit the enzyme activity. N-Bromosuccinimide completely inhibited enzyme activity. The relative substrate specificity of enzyme towards the various mannans is in the order of locust bean gum>guar gum>copra mannan, with K(m) of 0.11, 0.28, and 0.33 mg/ml, respectively. Since the enzyme is active over a wide range of pH and temperature, it could find potential use in the food-processing industry.
authors.affiliation: Department of Biochemistry, Gulbarga University, Gulbarga, Karnataka, India.
authors.forename: K
authors.initials: K
authors.lastname: Naganagouda
authors.forename: P V
authors.initials: PV
authors.lastname: Salimath
authors.forename: V H
authors.initials: VH
authors.lastname: Mulimani
mesh_terms: D001234:Aspergillus niger / Q000737:chemistry / Q000201:enzymology*; D005525:Food-Processing Industry; D005656:Fungal Proteins / Q000737:chemistry* / Q000302:isolation & purification* / Q000378:metabolism; D007700:Kinetics; D008970:Molecular Weight; D013379:Substrate Specificity; D044902:beta-Mannosidase / Q000737:chemistry* / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D044902:beta-Mannosidase