Presence of a Progesterone-Induced, Uterine Specific, Acid Phosphatase in Allantoic Fluid of Gilts

Abstract

A purple, basic, progesterone-induced glycoprotein having acid phosphatase activity was obtained from uterine flushings of intact gilts which were not pregnant. A protein having identical physical and chemical properties was also isolated from allantoic fluid collected on days 30, 35, 40, 45, 50, 55, 60, 70, 80, 90 and 100 of gestation. The purple protein from the non-pregnant uterus and allantoic fluid had the same: (a) molecular weight (32,000 ± 3,000); (b) electrophoretic properties; (c) chromatographic properties; (d) isoelectric point (pI = 9.7); (e) extinction maximum (545 nm); (f) molar extinction coefficient (approx. 2.0 × 10) ; (g) pH optimum of 4.9 when p-nitrophenylphosphate was used as substrate and (h) Michaelis constant of about 2.0 mM using p-nitrophenylphosphate as substrate. Acid phosphatase activity of this protein, from either source was enhanced two- to fourfold by the addition of .1 M ß-mercaptoethanol to the reaction mixture. Finally, antiserum prepared against the intra-uterine purple protein cross-reacted with the purple protein from allantoic fluid, and precipitin lines of identity have been demonstrated. It is suggested that the purple protein in allantoic fluid is produced by the uterine endometrial glands and transported into the chorio-allantoic membranes and allantoic fluid via the placental areolae beginning with their formation at about day 30 of gestation.