Hi
As far as I know, ascorbate peroxidase enzyme (APX) is the major enzyme involved in H2O2 scavenging. It is specific to plants and algae.
Recently, I was shocked when I came across an article in which APX and guaiacol peroxidase (GPOX) from fungi were unusually assayed !
In fact, GPOX activity monitoring in fungal cells is not surprising since the famous class II peroxidases such as lignin peroxidase that is found in fungi can use guaiacol as electron donor. However, APX assay is well conducted and APX activity was even higher than catalase that is well reported in fungi !
Although ascorbate (or erythroascorbate) could be a natrural substrate for many peroxidases, what do you think about the presence of APX enzyme in non-photosynthetic organisms and especially in fungi ?
Your contributions will be welcomed.
Mohammad
Hello, can't be evidence of ascorbate peroxidase in fungi. Peroxidase structures have significantly increased our understanding of the evolutionary and functional relationships within the plant peroxidase superfamily.
Three distantly related structural classes have emerged:
1. mitochondrial yeast cytochrome c peroxidase, chloroplast and cytosol ascorbate peroxidases, and gene duplicated bacterial peroxidase class I
2.secretory fungal peroxidases classII
3. classical, secretory plant peroxidases (class III).
So ascorbate peroxidase is class I peroxidase enzyme and catalyse the H2O2-dependent oxidation of ascorbate in plants, algae and certain cyanobacteria but not fungi. For this type of peroxidase your culture shuld be photosynthetic. My be we will see this activity in future in Radiotrophic fungus.
Good luck!
Ascorbate peroxidase (APX) is an enzyme family limited to plants and photosynthetic protists.
I agree Arvind Singh but in vitro biochemical assays reveal an APX activity from fungal samples. In this case, it is completely wrong to refer such activity to APX enzyme. Unfortunately, It was well stated by some researchers!!!
Hello, can't be evidence of ascorbate peroxidase in fungi. Peroxidase structures have significantly increased our understanding of the evolutionary and functional relationships within the plant peroxidase superfamily.
Three distantly related structural classes have emerged:
1. mitochondrial yeast cytochrome c peroxidase, chloroplast and cytosol ascorbate peroxidases, and gene duplicated bacterial peroxidase class I
2.secretory fungal peroxidases classII
3. classical, secretory plant peroxidases (class III).
So ascorbate peroxidase is class I peroxidase enzyme and catalyse the H2O2-dependent oxidation of ascorbate in plants, algae and certain cyanobacteria but not fungi. For this type of peroxidase your culture shuld be photosynthetic. My be we will see this activity in future in Radiotrophic fungus.
Good luck!
Thank you for your answer Mr. Karen A. Darbinyan . I completely agree.
Radiotrophic fungi is a curious case.
APXs are heme peroxidases and members of Class I non-animal peroxidases, which also include cytochrome c peroxidases (CCPs) and bacterial catalase peroxidases (CPs) (Welinder 1992, Passardi et al. 2007). CCPs are present in photosynthetic and non-photosynthetic eukaryotes, whereas APXs are only found in plastid-containing organisms, with some exceptions (Teixeira et al. 2004, Passardi et al. 2007, Nedelcu et al. 2008). While cyanobacteria have no APX gene, which is supported by genome-sequencing studies (Passardi et al. 2007), most eukaryotic algae possess more than one APX gene (see below).
reference:
Maruta, T., Sawa, Y., Shigeoka, S., & Ishikawa, T. (2016). Diversity and evolution of ascorbate peroxidase functions in chloroplasts: more than just a classical antioxidant enzyme?. Plant and Cell Physiology, 57(7), 1377-1386.
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