Biosynthesis
Doxorubicin (DXR) is a 14-hydroxylated version of daunorubicin, the immediate precursor of DXR in its biosynthetic pathway. Daunorubicin is more abundantly found as a natural product because it is produced by a number of different wild type strains of Streptomyces. In contrast, only one known non-wild type species, Streptomyces peucetius subspecies cesius ATCC 27952, was initially found to be capable of producing the more widely used doxorubicin. This strain was created by Arcamone et al. in 1969 by mutating a strain producing daunorubicin, but not DXR, at least in detectable quantities. Subsequently, Hutchinsons group showed that under special environmental conditions, or by the introduction of genetic modifications, other strains of Streptomyces can produce doxorubicin. His group also cloned many of the genes required for DXR production, although not all of them have been fully characterized. In 1996, Strohls group discovered, isolated and characterized dox A, the gene encoding the enzyme that converts daunorubicin into DXR.By 1999, they produced recombinant dox A, a cytochrome P450 oxidase, and found that it catalyzes multiple steps in DXR biosynthesis, including steps leading to daunorubicin. This was significant because it became clear that all daunorubicin-producing strains have the necessary genes to produce DXR, the much more therapeutically important of the two. Hutchinsons group went on to develop methods to improve the yield of DXR, from the fermentation process used in its commercial production, not only by introducing dox A encoding plasmids, but also by introducing mutations to deactivate enzymes that shunt DXR precursors to less useful products, for example baumycin-like glycosides.
Doxorubicin fluorescence is quenched by binding to DNA, and shielded by micelle encapsulation. It is also known to self-quench at high concentrations. In contrast, histone binding amplifies fluorescence. References
External links
 Media related to Doxorubicin at Wikimedia Commons
"Doxorubicin". Drug Information Portal. U.S. National Library of Medicine. "Doxorubicin hydrochloride". Drug Information Portal. U.S. National Library of Medicine.