Prostaglandin D2 (PGD2) is a structural isomer of prostaglandin E2 (PGE2). There is a 9-keto and 11-hydroxy group on PGE2 with these substituents reversed on PGD2. PGD2 is formed by two evolutionarily distinct, but functionally convergent, prostaglandin D synthases: lipocalin-type prostaglandin-D synthase aka Prostaglandin-H2 D-isomerase (PTDGS) and hematopoietic prostaglandin D synthase (HPGDS). One of the main differences between these two proteins is that HPGDS requires glutathione (GSH) for catalysis while PTDGS can function without this cofactor. Here, HPGDS with GSH promotes the isomerisation of prostaglandin H2 (PGH2) to prostaglandin D2 (PGD2) (Jowsey et al. 2001, Inoue et al. 2003).
In human blood, the major metabolic products of RvE1 are 10,11-dihydro-RvE1, 18-oxo-RvE1, and 20-hydroxy-RvE1 (Hong et al. 2008). 18-oxo-RvE1, formed by dimeric 15-hydroxyprostaglandin dehydrogenase (HPGD dimer) in the presence of NAD+, is also the major metabolite formed in murine lung and has been demonstrated to be devoid of activity, representing a mode of RvE1 inactivation (Arita et al. 2006). The exact enzymes that catalyze the formation of the other RvE1 metabolites mentioned here are currently unknown.
Cytosolic, dimeric 15-hydroxyprostaglandin dehydrogenase (HPGD dimer), in the presence of NAD+, can oxidise 17(S)-resolvin D1 (RvD1) to the novel metabolites 17(S)-oxo-RvD1 and 8-oxo-17(S)-RvD1. The 17(S)-oxo transformation effectively inactivates RvD1 activity whereas the 8-oxo metabolite retains most of its RvD1 activity (Sun et al. 2007). The epimeric 17(R) aspirin-triggered form (AT-RvD1) was also found to be able to resist rapid inactivation.
Prostaglandin D2 (PGD2) is a structural isomer of prostaglandin E2 (PGE2). There is a 9-keto and 11-hydroxy group on PGE2 with these substituents reversed on PGD2. PGD2 is formed by two evolutionarily distinct, but functionally convergent, prostaglandin D synthases: lipocalin-type prostaglandin-D synthase aka Prostaglandin-H2 D-isomerase (PTDGS) and hematopoietic prostaglandin D synthase (HPGDS). One of the main differences between these two proteins is that HPGDS requires glutathione (GSH) for catalysis while PTDGS can function without this cofactor. Here, PTDGS promotes the isomerisation of prostaglandin H2 (PGH2) to prostaglandin D2 (PGD2) (Zhou et al. 2010).