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A novel anthraquinone ring cleavage enzyme from Aspergillus terreus
Journal of Biochemistry
|May 1, 1988
Summary
Researchers discovered a novel enzyme, questin oxygenase, in Aspergillus terreus that cleaves anthraquinone questin. This enzyme requires NADPH and oxygen, suggesting it is a monooxygenase, and its activity can be reconstituted from two protein fractions.
Area of Science:
- Biochemistry
- Enzymology
- Microbial Metabolism
Background:
- Aspergillus terreus produces (+)-geodin, a complex anthraquinone.
- Understanding the metabolic pathways of secondary metabolites is crucial in mycology.
Purpose of the Study:
- To identify and characterize the enzyme responsible for questin ring cleavage.
- To elucidate the biochemical mechanism of desmethylsulochrin formation from questin.
Main Methods:
- Cell-free extract preparation from Aspergillus terreus.
- Enzyme assays using questin as substrate.
- Product identification via high-resolution mass spectroscopy and carrier dilution.
- Enzyme purification using DEAE-cellulose chromatography.
- Enzyme characterization including cofactor requirements and pH optimum.
Main Results:
- A novel enzyme, questin oxygenase, was identified, catalyzing questin ring cleavage to desmethylsulochrin.
- The enzyme requires NADPH and molecular oxygen, classifying it as a monooxygenase.
- Questin oxygenase activity was reconstituted from two DEAE-cellulose fractions (DE-I and DE-II), indicating a multi-component system.
Conclusions:
- Questin oxygenase is a novel monooxygenase involved in anthraquinone metabolism.
- The enzyme system appears complex, possibly involving electron transfer proteins for activity.
- Further research is needed to fully characterize the questin oxygenase system and its components.