LOC56985 discussion
The structural homology results obtained from the Dali server showed strong homology between the protein studied here and purple acid phosphatases. Purple acid phosphatases have been characterised as enzymes that catalyse phosphate ester hydrolysis under acidic conditions, are ~35kDa in size and contain two Fe ions at their catalytic centres (Wilcox, 1996). Similar acid phosphatases found in kidney bean, sweet potato and other plants contain Zn and Fe, two Fe or Mn at their cores.
Although the physiological role of purple acid phosphatases in the cell in not known, some of the proposed biological functions include iron transport, generation of reactive oxygen species and bone resorption (Oddie, et al., 2000); plant functions may include phosphate metabolism and generation of reactive oxygen species (Leung, Teixeira, Guddat, Mitić, & Schenk, 2007). Their localizations in the lysosomes of osteoclasts and macrophages support an intracellular monophosphate function in animals (Doi, Antanaitis, & Aisen, 1988). What is interesting from the results obtained here is that the ortholog from Zebrafish does not contain the characteristic iron core. The structure shows two Zinc ions at the catalytic site with the phosphate ion ligand. This may be the first case where a purple acid phosphatase does not contain this iron core.
Abstract | Introduction | Results | Discussion |
Conclusion | Method | References
