title: Biochemical properties of an extracellular trehalase from Malbranchea pulchella var. Sulfurea.
abstract: The thermophilic fungus Malbranchea pulchella var. sulfurea produced good amounts of extracellular trehalase activity when grown for long periods on starch, maltose or glucose as the main carbon source. Studies with young cultures suggested that the main role of the extracellular acid trehalase is utilizing trehalose as a carbon source. The specific activity of the purified enzyme in the presence of manganese (680 U/mg protein) was comparable to that of other thermophilic fungi enzymes, but many times higher than the values reported for trehalases from other microbial sources. The apparent molecular mass of the native enzyme was estimated to be 104 kDa by gel filtration and 52 kDa by SDS-PAGE, suggesting that the enzyme was composed by two subunits. The carbohydrate content of the purified enzyme was estimated to be 19 % and the pi was 3.5. The optimum pH and temperature were 5.0-5.5 and 55° C, respectively. The purified enzyme was stimulated by manganese and inhibited by calcium ions, and insensitive to ATP and ADP, and 1 mM silver ions. The apparent K(M) values for trehalose hydrolysis by the purified enzyme in the absence and presence of manganese chloride were 2.70 ± 0.29 and 2.58 ± 0.13 mM, respectively. Manganese ions affected only the apparent V(max), increasing the catalytic efficiency value by 9.2-fold. The results reported herein indicate that Malbranchea pulchella produces a trehalase with mixed biochemical properties, different from the conventional acid and neutral enzymes and also from trehalases from other thermophilic fungi.
authors: Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Avenida Bandeirantes, 3900, CEP 14040-901, Ribeirão Preto, SP, Brasil.
authors: Marita Gimenez
authors: MG
authors: Pereira
authors: Luis Henrique Souza
authors: LH
authors: Guimarães
authors: Rosa Prazeres Melo
authors: RP
authors: Furriel
authors: Maria de Lourdes Teixeira de Moraes
authors: Mde L
authors: Polizeli
authors: Hector Francisco
authors: HF
authors: Terenzi
authors: João Atílio
authors: JA
authors: Jorge
mesh_terms: D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D020536:Enzyme Activators / Q000378:metabolism; D004791:Enzyme Inhibitors; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D007700:Kinetics; D008345:Manganese / Q000378:metabolism; D008970:Molecular Weight; D020036:Onygenales / Q000201:enzymology*; D021122:Protein Subunits / Q000737:chemistry; D013696:Temperature; D014198:Trehalase / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D014199:Trehalose / Q000378:metabolism*
chemical_list: D020536:Enzyme Activators; D004791:Enzyme Inhibitors; D021122:Protein Subunits; D008345:Manganese; D014199:Trehalose; D014198:Trehalase