Immunohistochemistry of QSOX
- Last Updated on 01 April 2013
There are two QSOX orthologs in humans: QSOX1 and QSOX2. These images refer to the distribution of QSOX1 in human tissues and represent the unpublished observations of Dr. Donald L. Coppock, Dr. George K. Turi and their coworkers. The photomicrographs have been graciously provided by Dr. Coppock. The panels utilize an antibody raised against a peptide from the second thioredoxin domain of QSOX1 (found in both QSOX1a and QSOX1b isoforms [PubMed]). Tissues were fixed with formalin, the brown-to-puce stain is diaminobenzimide, and the counter stain is hematoxylin.
- Last Updated on 21 March 2013
The term "sulfhydryl oxidase" was introduced more than 50 years ago to describe an activity characterized from mammalian skin that catalyzed the reaction:
2 RSH + O2 → RS-SR + H2O2
Later, enzymes from milk (1967) and seminal vesicles (1979) were found to catalyze the same reaction. Eventually all three oxidases were recognized to be members of what is now know as the Quiescin-sulfhydryl oxidase (QSOX) family of flavin-linked oxidases. QSOXs are found in most eukaroyotes - from the smallest free-living eukaryote (Ostreococcus tauri) to humans. QSOXs are absent in the fungi. The evolutionarily unrelated Ero1 flavoprotein sulfhydryl oxidases have been found in all eukaryotes so far examined .
A chronology of some key events in the characterization of the flavin-linked sulfhydryl oxidases (together with other key developments in oxidative protein folding) is presented below.