[The characterization of free alpha subunit purified from the urine of normal term pregnant women].
Free alpha subunit (PU alpha) was extracted and purified from the urine of normal term pregnant women, and examined for molecular weight, electric charge, affinity to lectins (ConA, RCA and PNA) and the ability to combine with hCG beta in comparison with hCG alpha dissociated from hCG in vitro. The molecular weight of PU alpha was greater than that of hCG alpha in gel chromatography, but smaller in SDS-PAGE. However the free alpha subunits from the urine of patients with cancer were estimated to be larger than those of hCG alpha by both methods. In isoelectric focusing, while hCG alpha exhibited a neutral charge, PU alpha exhibited a negative charge. After treatment with sialidase, both hCG alpha and PU alpha were shifted to the basic region, indicating that they contained terminal sialic acid residues. The affinity to lectins indicated that PU alpha may contain both asparagine-linked and O-linked oligosaccharides, while hCG alpha contains asparagine-linked oligosaccharide only. PU alpha scarcely showed any combining activity with hCG beta, whereas hCG alpha combined actively. The O-linked oligosaccharide, which is not present in hCG alpha, may cause PU alpha to fail to combine with hCG beta.
D002241:Carbohydrates; D006063:Chorionic Gonadotropin / Q000378:metabolism; D018997:Chorionic Gonadotropin, beta Subunit, Human; D004560:Electricity; D005260:Female; D015292:Glycoprotein Hormones, alpha Subunit; D006801:Humans; D007525:Isoelectric Focusing; D037102:Lectins / Q000378:metabolism; D008970:Molecular Weight; D010446:Peptide Fragments / Q000378:metabolism; D010908:Pituitary Hormones, Anterior / Q000302:isolation & purification* / Q000378:metabolism / Q000652:urine; D011247:Pregnancy / Q000652:urine*; D011485:Protein Binding
D002241:Carbohydrates; D006063:Chorionic Gonadotropin; D018997:Chorionic Gonadotropin, beta Subunit, Human; D015292:Glycoprotein Hormones, alpha Subunit; D037102:Lectins; D010446:Peptide Fragments; D010908:Pituitary Hormones, Anterior