title: Characterization of an exoinulinase produced by Aspergillus terreus CCT 4083 grown on sugar cane bagasse.
abstract: Exoinulinase (beta-d-fructan fructohydrolase, EC 3.2.1.80) secreted by Aspergillus terreus CCT4083 was obtained using sugar cane bagasse, an agroindustrial residue, as a carbon source. It was further purified from the supernatant culture in a rapid procedure. The enzyme presented 57 kDa on SDS-PAGE and 56 kDa on gel filtration chromatography. Inulin was hydrolyzed by the purified enzyme, yielding d-fructose as the main product. This enzyme showed maximum activity at pH 4.0 and 60 degrees C and maintained more than 90 and 75% of its original activity at 40 and 50 degrees C, respectively, after 3.5 h of preincubation. The K(M) values for inulin, sucrose, and raffinose were 11, 4.20, and 27.89 mM, respectively, and d-fructose was a competitive inhibitor (K(i) = 47.55 mM). The activation energies for sucrose, raffinose, and inulin were 10.4, 5.61, and 4.44 kcal/mol, respectively. The characteristics of A. terreus exoinulinase were compared to those of inulinases isolated from other organisms. The exoinulinase traits presented especially good thermostability and the ability to produce pure d-fructose, suggesting its application to the production of high-fructose syrup.
authors.affiliation: Departamento de Bioquimica e Biologia Molecular, BIOAGRO, Universidade Federal de Vicosa, Vicosa, Brazil.
authors.forename: Juliana B
authors.initials: JB
authors.lastname: Coitinho
authors.forename: Valéria M
authors.initials: VM
authors.lastname: Guimarães
authors.forename: Maíra N
authors.initials: MN
authors.lastname: de Almeida
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Falkoski
authors.forename: José H
authors.initials: JH
authors.lastname: de Queiróz
authors.forename: Sebastião T
authors.initials: ST
authors.lastname: de Rezende
mesh_terms: D001230:Aspergillus / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D003470:Culture Media / Q000378:metabolism; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D015870:Gene Expression; D006026:Glycoside Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D007220:Industrial Waste / Q000032:analysis*; D007444:Inulin / Q000378:metabolism; D007700:Kinetics; D012037:Refuse Disposal; D031786:Saccharum / Q000737:chemistry / Q000382:microbiology*; D013379:Substrate Specificity
chemical_list: D003470:Culture Media; D005656:Fungal Proteins; D007220:Industrial Waste; D007444:Inulin; D006026:Glycoside Hydrolases; C023086:inulinase; C044118:fructan beta-fructosidase