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

G Xia1, C Jin, J Zhou

  • 1State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.

European Journal of Biochemistry
|July 17, 2001
PubMed

Insights

Researchers isolated a stable extracellular chitinase from Aspergillus fumigatus. This enzyme exhibits broad substrate specificity and both endo- and exo-hydrolytic activities, offering potential applications in biotechnology.

Area of Science:

  • Biochemistry
  • Mycology
  • Enzymology

Background:

  • Fungal chitinases are crucial for morphogenesis and are produced throughout fungal growth.
  • Aspergillus fumigatus is a significant opportunistic pathogen causing severe infections in immunocompromised individuals.
  • A. fumigatus is known to produce chitinase, an enzyme involved in breaking down chitin.

Purpose of the Study:

  • To isolate and characterize a stable extracellular chitinase from Aspergillus fumigatus YJ-407.
  • To determine the enzyme's properties, including molecular mass, isoelectric point, optimal activity, stability, and substrate specificity.
  • To investigate the enzyme's hydrolytic and transglycosyl activities.

Main Methods:

  • Induction and isolation of extracellular chitinase using ammonium sulfate precipitation and DEAE-cellulose chromatography.
  • Characterization of enzyme properties including molecular mass estimation (SDS-PAGE), isoelectric point determination, and activity assays at various pH and temperatures.
  • Determination of Michaelis constants (Km) for swollen chitin and chitosan.
  • Analysis of hydrolysis products to elucidate enzyme activity (endo- and exo-hydrolytic).

Main Results:

  • An exceptionally stable extracellular chitinase was successfully isolated from A. fumigatus YJ-407.
  • The enzyme has a molecular mass of 46,000 Da, an isoelectric point of pH 5.6, and is optimally active at pH 5.0 and 60°C.
  • It exhibits stability over a broad pH range (4-8) and below 45°C, with essential roles for tryptophan and carboxyl groups.
  • The enzyme efficiently hydrolyzes glycol chitin and partially deacetylated chitosan, demonstrating both endo- and exo-hydrolytic activities, along with transglycosyl activity.

Conclusions:

  • The isolated A. fumigatus chitinase is highly stable and possesses versatile hydrolytic and transglycosyl activities.
  • Its broad substrate specificity and stability suggest significant potential for biotechnological applications, such as in chitin degradation and modification.
  • Further research into this enzyme could lead to novel applications in various industries, including agriculture and medicine.

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