An iron-containing phosphatase induced by progesterone in the uterine fluids of pigs.
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abstract
A basic, progesterone induced, intrauterine glycoprotein with a purple coloration can be purified from the uterine fluids of ovariectomized female pigs given daily doses of progesterone, by successive chromatography on columns of CM cellulose and Sephadex G 100. The protein contains 1 atom of iron per 32,000 molecular weight polypeptide and shows phosphatase activity toward p nitrophenylphosphate as substrate. The pH optimum of the enzyme is 4.9 and the apparent K(m) is 2.2 mM at 30. Activity is enhanced 2 to 4 fold in presence of mercaptoethanol, although the K(m) remains unchanged. Under such optimal conditions 1 molecule of enzyme can hydrolyze approximately 5 X 103 molecules of substrate per min. Activity is inhibited by fluoride, arsenate, phosphate, and molybdate. To a lesser extent, the enzyme will catalyze the hydrolysis of ATP and pyrophosphate, but has very low activity toward glycerophosphate and D glucose 6 phosphate. The activation of the enzyme by mercaptoethanol is accompanied by a shift in the extinction maximum from 545 nm to around 510 nm. Sodium dithionite causes loss of color and inactivates the enzymatic activity completely. The precise role of the protein in the early pregnant uterus, however, remains unknown. (31 references).
