title: Extracellular beta-D-glucosidase from Chaetomium thermophilum var. coprophilum: production, purification and some biochemical properties.
abstract: The thermophilic fungus Chaetomium thermophilum var. coprophilum produced large amounts of extracellular and intracellular beta-glucosidase activity when grown on cellulose or cellobiose as carbon sources. The presence of glucose in the culture medium drastically decreased the level of beta-glucosidase activity, while cycloheximide prevented the induction of the extracellular enzyme activity by cellobiose. An extracellular beta-glucosidase induced by avicel was purified by a procedure involving acetone precipitation and chromatography on two DEAE-cellulose columns. The purified enzyme was a basic protein, with a carbohydrate content of 73%. The deglycosylated enzyme exhibited a molecular mass of 43 kDa, with pH and temperature optima of 5.5 and 65 degrees C respectively. The beta-glucosidase hydrolysed only cellobiose and p-nitrophenyl-beta-D-glucopyranoside, exhibiting apparent Km values of 3.13 mM and 0.76 mM, respectively. The native purified enzyme was stable up to 2 hours at 60 degrees C, and its thermal stability was directly dependent on glycosylation.
authors.affiliation: Departamentos de Biologia e Química, Universidade de São Paulo, Faculdade de Filosofia, Ciências e Letras de Riberirão Preto, 14040-901 Ribeirão Preto, São Paulo, Brasil.
authors.forename: Leandra Lórice
authors.initials: LL
authors.lastname: Venturi
authors.forename: Maria de Lourdes
authors.initials: Mde L
authors.lastname: Polizeli
authors.forename: Héctor Francisco
authors.initials: HF
authors.lastname: Terenzi
authors.forename: Rosa dos Prazeres Melo
authors.initials: Rdos P
authors.lastname: Furriel
authors.forename: João Atílio
authors.initials: JA
authors.lastname: Jorge
mesh_terms: D002475:Cellobiose / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism; D002597:Chaetomium / Q000201:enzymology* / Q000254:growth & development; D003470:Culture Media; D003513:Cycloheximide / Q000494:pharmacology; D004795:Enzyme Stability; D005947:Glucose / Q000378:metabolism; D006358:Hot Temperature; D001617:beta-Glucosidase / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D003470:Culture Media; D002475:Cellobiose; D002482:Cellulose; D003513:Cycloheximide; D001617:beta-Glucosidase; D005947:Glucose