[Physico-chemical characteristics of pregnancy-specific protein in the rat]

Molecular weight of PSP, determined by gel-filtration on Sephadex G-200, is 130 000 +/- 4 000 D and, according to the Laemmli method with SDS, 85 000 +/- 2 000 D. The protein was detected in the zone of beta 1-globulins, its relative electrophoretic mobility is 0.45 +/- 0,2. PSP is heterogeneous by electric charge; at electrofocusing this protein was revealed in the following isoelectric points (pI); 5.85, 6.11, and 6.57. PSP was precipitated with ammonium sulfate (20-50% of saturation). Iron, carbohydrates, lipids were not found histochemically in PSP and it did not manifest the esterase and phosphatase activity.