Purification and properties of xylanase from the thermophilic fungus, Humicola lanuginosa (Griffon and Maublanc) Bunce

Anand, Lalitha and Krishnamurthy, S and Vithayathil, PJ (1990) Purification and properties of xylanase from the thermophilic fungus, Humicola lanuginosa (Griffon and Maublanc) Bunce. In: Archives of Biochemistry and Biophysics, 276 (2). pp. 546-553.

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Abstract

An extracellular xylanase was purified to homogeneity from the culture filtrate of the thermophilic fungus, Humicola lanuginosa (Griffon and Maublanc) Bunce and its properties were studied. A fourfold purification and a yield of 8% were achieved. The molecular-weight of the protein was found to be 22,500 based on electrophoretic mobility and 29,000 by gel filtration behavior. The protein is rich in acidic amino acids, glycine and tyrosine, and poor in sulfur-containing amino acids. The kinetic properties of the enzyme are similar to those of other fungal xylanases. The enzyme shows high affinity toward larchwood xylan (Km = 0.91 mg/ml) and hydrolyzes only xylan. The enzyme becomes inactivated when stored for more than 2 months at −20 °C in the dry state. Such an inactivation has not been reported so far for any xylanase. Using chromatographic techniques, one species of protein differing from the native protein in charge but enzymatically active was isolated in low yields. However, a large molecular-weight species of the protein devoid of enzyme activity was isolated in substantial quantities and further characterized. Based on ultracentrifugation and gel electrophoretic studies, it was concluded that this species may be an aggregate of the native protein and that such an aggregation might be taking place on storage in the dry state at −20 °C, leading to loss in activity.

Item Type:	Journal Article
Publication:	Archives of Biochemistry and Biophysics
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Department/Centre:	Division of Biological Sciences > Biochemistry
Date Deposited:	12 Jan 2011 11:14
Last Modified:	12 Jan 2011 11:14
URI:	http://eprints.iisc.ac.in/id/eprint/34974

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