Purification and properties of a thermostable extracellular beta-D-xylosidase produced by a thermotolerant Aspergillus phoenicis
2001
Rizzatti, A.C.S. | Jorge, J.A. | Terenzi, H.F. | Rechia, C.G.V. | Polizeli, M.L.T.M.
A beta-D-xylosidase was purified from cultures of a thermotolerant strain of Aspergillus phoenicis grown on xylan at 45 degrees C. The enzyme was purified to homogeneity by chromatography on DEAE-cellulose and Sephadex G-100. The purified enzyme was a monomer of molecular mass 132 kDa by gel filtration and SDS-PAGE. Treatment with endoglycosidase H resulted in a protein with a molecular mass of 104 kDa. The enzyme was a glycoprotein with 43.5% carbohydrate content and exhibited a pl of 3.7. Optima of temperature and pH were 75 degrees C and 4.0-4.5, respectively. The activity was stable at 60 degrees C and had a K(m) of 2.36 mM for p-nitrophenyl-beta-D-xylopiranoside. The enzyme did not exhibit xylanase, cellulase, galactosidase or arabinosidase activities. The purified enzyme was active against natural substrates, such as xylobiose and xylotriose.
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