Related Experiment Videos
Characterisation and biosynthesis of D-erythroascorbic acid in Phycomyces blakesleeanus
Alberto Baroja-Mazo1, Pilar del Valle, Javier Rúa
1Departamento de Bioquímica y Biología Molecular, Universidad de León, León, Spain.
Fungal Genetics and Biology : FG & B
|April 6, 2005
Summary
Fungi, including Phycomyces blakesleeanus, synthesize D-erythroascorbate, not L-ascorbate, suggesting ancient origins. This compound and its glucoside show antioxidant potential and are linked to fungal growth phases.
Area of Science:
- Mycology
- Biochemistry
- Fungal Metabolism
Background:
- Fungi synthesize D-erythroascorbate instead of L-ascorbate, indicating an ancient evolutionary origin in the common fungal ancestor.
- Phycomyces blakesleeanus accumulates D-erythroascorbate and its glucoside at higher concentrations than other fungal species.
Purpose of the Study:
- To investigate the synthesis, accumulation, and potential antioxidant role of D-erythroascorbate and its glucoside in Phycomyces blakesleeanus.
- To identify enzymes involved in the conversion of exogenous sugars to D-erythroascorbate and related compounds.
Main Methods:
- Identification and quantification of D-erythroascorbate and D-erythroascorbate glucoside in Phycomyces blakesleeanus.
- Enzyme purification and characterization of NAD-dependent D-arabinose dehydrogenase.
- Analysis of substrate specificity and product formation for the purified enzyme and fungal mycelium.
Main Results:
- D-erythroascorbate glucoside exhibits antioxidant activity comparable to L-ascorbate but with greater stability.
- Free D-erythroascorbate levels correlate with the exponential growth phase of mycelium.
- Phycomyces blakesleeanus converts D-arabinose, L-galactose, and L-fucose into D-erythroascorbate, its glucoside, L-ascorbate, and 6-deoxyascorbate, respectively.
Conclusions:
- The synthesis of D-erythroascorbate is an ancient fungal trait.
- D-erythroascorbate and its glucoside play significant roles in fungal physiology, potentially as antioxidants.
- Specific enzymes, like D-arabinose dehydrogenase, are crucial for the interconversion of various sugar acids in fungi.