title: Beta-core fragments are contaminants of the World Health Organization Reference Preparations of human choriogonadotrophin and its alpha-subunit.
abstract: Highly purified preparations of human choriogonadotrophin (hCG), hCG alpha and hCG beta, including those preparations which are being distributed by the World Health Organization as International Standards, cross-reacted in a new radioimmunoassay with increased relative specificity for the beta-core fragment of hCG. A major portion of the beta-core immunoreactivity in the hCG and hCG alpha preparations eluted from Sephadex G-100 in a position (approximate apparent molecular size 15,000-18,000) corresponding to that of purified beta-core fragment prepared from pregnancy urine. However, in the case of hCG beta-subunit preparations, virtually all of the beta-core cross-reacting material eluted from Sephadex G-100 in the same fractions as the native hCG beta-subunit. Quantitatively, the cross-reacting beta-core material accounts for less than 1% (w/w) of the total hCG or subunit immunoreactivity, as measured by conventional radioimmunoassays. The presence of the beta-core fragments as discrete molecular components of the hCG and hCG alpha preparations should be borne in mind when these preparations are used to calibrate new radioimmunoassays for hCG-related molecules.
mesh_terms: D006063:Chorionic Gonadotropin / Q000032:analysis* / Q000592:standards*; D018997:Chorionic Gonadotropin, beta Subunit, Human; D002850:Chromatography, Gel; D004340:Drug Contamination; D015292:Glycoprotein Hormones, alpha Subunit; D006801:Humans; D008970:Molecular Weight; D010446:Peptide Fragments / Q000032:analysis*; D010908:Pituitary Hormones, Anterior / Q000592:standards*; D011863:Radioimmunoassay; D012015:Reference Standards; D014944:World Health Organization
chemical_list: D006063:Chorionic Gonadotropin; D018997:Chorionic Gonadotropin, beta Subunit, Human; D015292:Glycoprotein Hormones, alpha Subunit; D010446:Peptide Fragments; D010908:Pituitary Hormones, Anterior