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Emodin O-methyltransferase from Aspergillus terreus
Archives of Microbiology
|January 1, 1992
Summary
Researchers identified and purified emodin O-methyltransferase from Aspergillus terreus. This enzyme catalyzes questin formation from emodin and S-adenosyl-L-methionine, showing high substrate specificity and low Km values.
Area of Science:
- Biochemistry
- Enzymology
- Mycology
Background:
- Emodin O-methyltransferase (EOMT) is crucial for secondary metabolite biosynthesis.
- Identification of EOMT in Aspergillus terreus provides insights into fungal metabolic pathways.
Purpose of the Study:
- To identify and characterize the emodin O-methyltransferase from Aspergillus terreus.
- To elucidate the enzymatic properties and substrate specificity of EOMT.
Main Methods:
- Enzyme purification using multiple chromatography techniques (DEAE-cellulose, Phenyl Sepharose, Q-Sepharose, Hydroxyapatite, CM-cellulose).
- Determination of molecular weight via gel filtration and SDS-PAGE.
- Enzyme kinetics and substrate specificity assays.
Main Results:
- Emodin O-methyltransferase was purified to homogeneity from Aspergillus terreus.
- The enzyme exists as a homohexamer (322 kDa) and functions optimally at pH 7-8.
- Demonstrated strict substrate specificity for emodin and S-adenosyl-L-methionine with low Km values (3.4 x 10(-7) M and 4.1 x 10(-6) M, respectively).
Conclusions:
- The purified emodin O-methyltransferase from Aspergillus terreus is a homohexameric enzyme.
- The enzyme efficiently catalyzes the methylation of emodin to form questin.
- Characterization provides a foundation for understanding fungal secondary metabolism and potential biotechnological applications.