Comparison of human normal, full-term, fetal and adult plasminogen by physical and chemical analyses

Abstract

Human fetal plasminogen was isolated from fetal cord blood obtained from full-term normal newborns. Two fetal plasminogen preparations were characterized by physical analyses and compared to adult human Glu-plasminogen. The protein concentration of plasminogen in each full-term fetal plasma was approximately 50% of the concentration found in adult plasma. The specific activity of the isolated plasminogen from both full-term fetal plasmas was 28.8 +/- 1.5 IU/mg protein, approximately the same as that of adult Glu-plasminogen. No significant difference was observed in the rate at which plasmin was generated from the normal fetal plasminogen and the adult Glu-plasminogen using streptokinase, urokinase, and tissue plasminogen activator. Electrophoretic analyses in an acrylamide gel/sodium dodecyl sulfate dissociating system showed that the fetal plasminogens and the adult Glu-plasminogen were the same molecular size. Analyses in an acrylamide gel isoelectric focusing system indicated that fetal and adult plasminogen both contained the same twelve isoelectric forms, however, there was a slight difference in the distribution of the isoelectric forms. The fetal and adult plasminogens both contained 792 +/- 1 amino acid residues, and there were no significant differences in amino acid composition between the fetal and adult preparations. These comparisons indicate that normal, full-term, fetal and adult Glu-plasminogen are identical.