Purification of prostaglandin E2‐9‐oxoreductase from human decidua vera

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Abstract
Prostaglandin E2-9-oxoreductase (PGE2-9-OR), the enzyme which converts prostaglandin E2 (PGE2) to prostaglandin F2α (PGF2α), has been detected in human decidua vera. A 105-fold purification was achieved when the centrifuged homogenate was fractionated sequentially by DEAE—Trisacryl, hydroxyapatite—agarose gel, ultrogel AcA 44 and Matrex gel blue A gel chromatographies. The following kinetic constants for PGE2-9-OR have been obtained. The equilibrium constant with respect to PGE2 is 83 μM, the Michaelis constant, K m, for PGE2 is 80 μM, for NADPH 1.6 μM. The maximal velocity for the forward reaction is V 1 = .203 pmol/min. The enzyme was inhibited by progesterone, oestradiol-17β, cortisol and pharmaceutical drugs. An activating effect could be demonstrated with Ca2+ and oxytocin. The occurrence of PGE2-9-OR in the decidua vera suggests that this enzyme may be responsible for the transformation of PGE2 to PGF2α in these tissues. This may be an important mechanism for the initiation and maintenance of uterine contractions.