An aspergillus chitosanase with potential for large-scale preparation of chitosan oligosaccharides

Yu Cheng Chih Yu Cheng, Yaw-Kuen Li*

*Corresponding author for this work

研究成果: Article同行評審

85 引文 斯高帕斯(Scopus)

摘要

A chitosan-degrading fungus, designated Aspergillus sp. Y2K, was isolated from soil. The micro-organism was used for producing chitosanase (EC 3.2.1.132) in a minimal medium containing chitosan as the sole carbon source. The induced chitosanase was purified to homogeneity from the culture filtrate by concentration and cationic SP-Sepharose chromatography. The purified enzyme is a monomer with an estimated molecular mass of 25 kDa by SDS/PAGE and of 22 kDa by gelfiltration chromatography. pI, optimum pH and optimum temperature values were 8.4, 6.5 and 65-70 °C, respectively. The chitosanase is stable in the pH range from 4 to 7.5 at 55 °C. Higher deacetylated chitosan is a better substrate. Chitin, xylan, 6-O-sulphated chitosan and O-carboxymethyl chitin were indigestible by the purified enzyme. By endo-splitting activity, the chitosanase hydrolysed chitosan to form chitosan oligomers with chitotriose, chitotetraose and chitopentaose as the major products. The enzyme hydrolyses chitohexaose to form chitotriose, while the chitopentaose and shorter oligomers remain intact. The N-terminal amino acid sequence of the enzyme was determined as YNLPNNLKQIYDDHK, which provides useful information for further gene cloning of this enzyme. A 275 g-scale hydrolysis of chitosan was performed. The product distribution was virtually identical to that of the small-scale reaction. Owing to the simple purification process and high stability of the enzyme, it is potentially valuable for industrial applications.

原文English
頁(從 - 到)197-203
頁數7
期刊Biotechnology and Applied Biochemistry
32
發行號3
DOIs
出版狀態Published - 1 十二月 2000

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