E. histolytica lacks catalase and glutathione-dependent enzymes normally associate with oxygen-related detoxification (Fahey et al. 1984). It contains a single copy of an iron-containing superoxide dismutase (Tannich et al. 1991) to remove superoxide ion and several peroxiredoxins capable of removing both hydrogen peroxide and organic peroxides, including phospholipid hydroperoxides that would otherwise damage the cell membranes. Peroxiredoxins depend on thioredox-in and thioredoxin reductase and candidate genes for both of these have been found. Other proteins that may protect the organism from intracellular peroxide have also been identified, including genes encoding rubrerythrin and flavoprotein A, which may detoxify nitric oxide (Bruchhaus I, unpublished analyses). The redundancy of anti-oxidant pathways underscores the sensitivity of this amitochondrial organism to the presence of oxygen. Experimental evidence suggests that only low levels of oxygen can be tolerated and in the absence of the above pathways it would be even lower.
The absence of glutathione from E. histolytica has been known for many years (Fahey et al. 1984) and as mentioned earlier it is thought that cysteine acts as a functional replacement in this organism. Conflicting reports of the presence of trypa-nothione exist (Ariyanayagam and Fairlamb 1999; Ondarza et al. 2005). The putative trypanothione reductase gene reported from strain HK-9 (Tamayo et al. 2005) has no homologue in the genome sequence (strain HM-1:IMSS), nor in the (admittedly incomplete) genomes of four other Entamoeba species.
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Detoxification is something that is very important to the body, but it is something that isn't understood well. Centuries ago, health masters in the East understood the importance of balancing and detoxifying the body. It's something that Western medicine is only beginning to understand.