A novel chitinase having a unique mode of action from Aspergillus fumigatus YJ-407

Guoqing Xia, Chunsheng Jin, Ju Zhou, Shoujun Yang, Shuzheng Zhang, Cheng Jin

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Chitinases are produced throughout the growth process of fungi and are thought to play important roles in morphogenesis. Aspergillus fumigatus, is an important pathogen of immunocompromised individuals in which it causes pneumonia and invasive disseminated disease with high mortality; it is also known to produce chitinase. We have induced an exceptionally stable extracellular chitinase in A. fumigatus YJ-407, which could be isolated readily in a homogeneous form by using ammonium sulfate precipitation followed by DEAE-cellulose chromatography and preparative PAGE. The molecular mass of this chitinase was estimated to be 46 000 by SDS/PAGE, and its isoelectric point was pH 5.6. The enzyme was most active at pH 5.0 and 60°C, and was inhibited strongly by Hg2+, Pb2+, Ag+, Fe2+, Mn2+ and Zn2+. The enzyme was stable over a broad pH range 4-8 and below 45°C. Tryptophan and carboxyl groups were found to be essential for the enzyme activity. The Michaelis constants for swollen chitin and chitosan were 1.12 mg·mL-1 and 1.84 mg·mL-1, respectively. The enzyme showed maximum activity towards glycol chitin and partially deacetylated chitosan, and lower activity towards colloidal chitin. Analysis of the hydrolysis product showed that the enzyme has both endo- and exo-hydrolytic activities. In addition, a transglycosyl activity was also observed.
    Original languageEnglish
    Pages (from-to)4079-4085
    Number of pages6
    JournalEuropean Journal of Biochemistry
    Volume268
    Issue number14
    DOIs
    Publication statusPublished - 2001

    Keywords

    • Aspergillus fumigatus
    • Chitinase
    • Endochitinase
    • Exochitinase
    • Transglycosylation

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