Characterization of prostaglandin E2 20-hydroxylase of sheep vesicular glands.
The microsomal fraction of homogenates of the sheep vesicular glands, supplemented with 1 mM NADPH, metabolized 0.2 mM prostaglandin E2 to 20-hydroxyprostaglandin E2 at a rate of 76 +/- 9 pmol/min per mg of protein (with a Km of about 0.1 mM and a Vmax of about 0.1 nmol/min per mg of protein). Prostaglandin E1 was metabolized at a rate of only 8.5% of that of prostaglandin E2. The metabolism of prostaglandin E2 was decreased by 66% using 1 mM NADH instead of NADPH. alpha-Naphthoflavone (50 microM) and carbon monoxide inhibited the 20-hydroxylase by more than 60%, while 1 mM beta-diethylaminoethyl-2,2-diphenyl-pentanoate and 1 mM metyrapone inhibited it by less than 50%. The enzyme catalyzed the incorporation of atmospheric oxygen into the substrate. The findings suggest that the 20-hydroxylase could be a cytochrome P-450. The 20-hydroxylase could not be detected in vesicular glands of five rams 3 weeks after castration. The function of the enzyme is presumably to create the high level of 20-hydroxyprostaglandin E compounds in ram semen.
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D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003577:Cytochrome P-450 Enzyme System; D015232:Dinoprostone; D008401:Gas Chromatography-Mass Spectrometry; D008297:Male; D008861:Microsomes / Q000201:enzymology; D006899:Mixed Function Oxygenases / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism; D009919:Orchiectomy; D010100:Oxygen / Q000378:metabolism; D011458:Prostaglandins E / Q000378:metabolism*; D012669:Seminal Vesicles / Q000201:enzymology*; D012756:Sheep
D011458:Prostaglandins E; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; C026961:prostaglandin omega hydroxylases; D015232:Dinoprostone; D010100:Oxygen