title: Purification and molecular properties of an alpha-galactosidase synthesized and secreted by Aspergillus nidulans.
abstract: alpha-Galactosidases from mycelial extract and culture filtrate of Aspergillus nidulans have been purified to homogeneity and utilised to obtain polyclonal antibodies anti-alpha-galactosidase. The enzymatic characteristics and the cross reactivity of the antibodies suggest that alpha-galactosidases isolated from the two sources were the same enzyme. Thus, A. nidulans synthesized and secreted only one enzymatic form of alpha-galactosidase which is a multimeric enzyme of 370 kDa composed of four monomers of 87 kDa and a pI of 6.3. The optimum temperature of activity was 50 degrees C and the optimum pH 4-5. The enzyme was stable over a wide range of pH but quite unstable to temperature. alpha-Galactosidase of A. nidulans is a very specific enzyme, it is active only on p-nitrophenyl-alpha-D-galactoside (PNPG), melibiose and raffinose. When PNPG was utilised as substrate melibiose, raffinose, galactose and glucose were competitive inhibitors of the activity.
authors.affiliation: Departamento de Microbiología y Parasitología, Universidad de Alcalá de Henares, Madrid, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Ríos
authors.forename: A M
authors.initials: AM
authors.lastname: Pedregosa
authors.forename: I
authors.initials: I
authors.lastname: Fernández Monistrol
authors.forename: F
authors.initials: F
authors.lastname: Laborda
mesh_terms: D001233:Aspergillus nidulans / Q000201:enzymology*; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D007120:Immunochemistry; D008970:Molecular Weight; D011487:Protein Conformation; D013696:Temperature; D000519:alpha-Galactosidase / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification*
chemical_list: D000519:alpha-Galactosidase