Purification and characterization of xylanases fromAspergillus giganteus
- 156 Downloads
A strain ofAspergillus giganteus cultivated in a medium with xylan produced two xylanases (xylanase I and II) which were purified to homogeneity. Their molar mass, estimated by SDS-PAGE, were 21 and 24 kDa, respectively. Both enzymes are glycoproteins with 50 °C temperature optimum; optimum pH was 6.0–6.5 for xylanase I and 6.0 for xylanase II. At 50 °C xylanase I exhibited higher thermostability than xylanase II. Hg2+, Cu2+ and SDS were strong inhibitors, 1,4-dithiothreitol stimulated the reaction of both enzymes. Both xylanases are xylan-specific; kinetic parameters indicated higher efficiency in the hydrolysis of oat spelts xylan. In hydrolysis of this substrate, xylotriose, xylotetraose and larger xylooligosaccharides were released and hence the enzymes were classified as endoxylanases.
Unable to display preview. Download preview PDF.
- Attili D.S.: Isolamento, indentificação e ecologia de fungos celuloliticos do solo da estação ecológica de Juréia-Itatins, São Paulo.PhD Thesis. UNESP, Rio Claro (Brazil) 1994.Google Scholar
- Prade R.A.: Xylanases: from biology to biotechnology.Biotech.Genet.Eng.Rev. 13, 101–131 (1995).Google Scholar
- Scopes R.K.:Protein Purification: Principles and Practice, 3rd ed. Springer-Verlag, New York 1994.Google Scholar
- Vogel H.J.: A convenient growth medium forNeurospora (Medium N).Microb.Genet.Bull. 13, 42–43 (1956).Google Scholar
- Woodward J.: Xylanases: functions, properties and applications.Topics Enzyme Ferment.Biotechnol. 8, 9–30 (1984).Google Scholar