Production, purification and characterization of a minor form of xylanase from Aspergillus versicolor

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Data

2005-01-01

Autores

Carmona, E. C.
Fialho, M. B.
Buchgnani, E. B.
Coelho, G. D.
Brocheto-Braga, M. R.
Jorge, J. A.

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Editor

Elsevier B.V.

Resumo

A strain of Aspergillus versicolor produces a xylanolytic complex containing two components, the minor component being designated xylanase II. The highest production of xylanase II was observed in cultures grown for 5 days in 1% wheat bran as carbon source, at pH 6.5. Xylanase II was purified 28-fold by DEAE-Sephadex and HPLC GF-5 10 gel filtration. Xylanase II was a monomeric glycoprotein, exhibiting a molecular mass of 32 kDa with 14.1% of carbohydrate content. Optimal pH and temperature values for the enzyme activity were about 6.0-7.0 and 55 degreesC, respectively. Xylanase II thermoinactivation at 50degreesC showed a biphasic curve. The ions Hg2+, Cu2+ and the detergent SDS were strong inhibitors, while Mn2+ ions and dithiothreitol were stimulators of the enzyme activity. The enzyme was specific for xylans, showing higher specific activity on birchwood xylan. The Michaelis-Menten constant (K-m) for birchwood xylan was estimated to be 2.3 mg ml(-1) while maximal velocity (V-max) was 233.1 mumol mg(-1) min(-1) of protein. The hydrolysis of oat spell xylan released only xylooligosaccharides. Published by Elsevier Ltd.

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Palavras-chave

Aspergillus versicolor, xylanase, endoxylanase, enzyme purification

Como citar

Process Biochemistry. Oxford: Elsevier B.V., v. 40, n. 1, p. 359-364, 2005.