NON-IDENTICAL REACTION OF UNDISSOCIATED HCG AND HCG-β SUBUNIT WITH ANTI-HCGβ SERUM

1975 ◽  
Vol 80 (2) ◽  
pp. 374-379 ◽  
Author(s):  
J. Arends
Keyword(s):  
Gel Filtration ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Β Subunit ◽  
Suitable Standard

ABSTRACT Based on gel-filtration experiments, estimates of the content are given of undissociated human chorionic gonadotrophin (HCG) and HCG-β subunit in HCG preparations. Radioimmunoassay of three HCG preparation using an antiserum against HCG-β subunit showed that the slope of displacement curves was dependent on the ratio of HCG-β subunit to undissociated HCG, the slope being steeper (negative) with increasing ratio. The implication of this observation on the choice of a suitable standard for HCG-β radioimmunoassay is discussed.

SUBUNITS OF HUMAN CHORIONIC GONADOTROPHIN: IMMUNOLOGICAL AND BIOLOGICAL STUDIES

1975 ◽  
Vol 79 (4) ◽  
pp. 749-766 ◽  
Author(s):  
S. Donini ◽  
I. D'Alessio ◽  
P. Donini
Keyword(s):  
Biological Activity ◽  
Gel Filtration ◽  
Cross Reactivity ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Biologically Active ◽  
Β Subunit ◽  
Reactive Material ◽  
Biological Studies ◽  
The Cross

ABSTRACT The α and β subunits of human chorionic gonadotrophin (hCG) were prepared by incubation in 8 m urea, pH 4.5. The separation of the two subunits was obtained by DEAE-Sephadex A-25 chromatography and purification was carried out by gel filtration on Sephadex G-100. The β subunit obtained was biologically active and was therefore further purified by affinity chromatography using as immuno-adsorbent the α antibodies coupled to Sepharose 4B. The β subunit so purified showed a biological activity less than 1 IU/mg. The immunological and biological properties of the hCG subunits have been studied. It was found that the anti hCG β serum can discriminate between hCG and hLH and that in the 125I-hCG + anti-β serum radioimmunoassay, the cross-reactivity of pituitary hLH was lower than that of urinary hLH. Moreover, it was observed that the less purified was the urinary LH preparation, the higher was the cross-reactivity. Therefore we considered the hypothesis that during the purification of human menopausal gonadotrophin (hMG) some LH subunits or smaller immunoreactive fragments could have been discarded with the waste fractions. In order to test the validity of this hypophysis, all the protein fractions obtained during the purification of the hMG were gel-filtered on Sephadex G-100. The immunoreactivity of the effluents from the gel filtration was tested by hCG, hCG-β, hCG-α and hLH radioimmunoassays. While the α reactive material was found in some fractions as a peak having the same Ve/Vo value as hCG-α, the β reactive material present in the crude hMG fractions was not observed in other fractions. The cross-reactivity with the anti β serum was very low and was found in the LH region of the gel chromatogram. Furthermore, the neutralization of the biological activity of hCG and of urinary and pituitary LH by the anti hCG β serum was studied by incubating a fixed amount of the three hormones with increasing volumes of antiserum and measuring the LH activity after incubation by the OAAD test. It was observed that the anti hCG β serum inhibits hCG more than urinary or pituitary LH.

STUDIES ON A HUMAN CHORIONIC GONADOTROPHIN-LIKE MATERIAL PRESENT IN NON-PREGNANT SUBJECTS

1978 ◽  
Vol 89 (3) ◽  
pp. 492-505 ◽  
Author(s):  
D. M. Robertson ◽  
H. Suginami ◽  
H. Hernandez Montes ◽  
C. P. Puri ◽  
S. K. Choi ◽  
...  
Keyword(s):  
Gel Filtration ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Specific Sequence ◽  
Gonadotrophin Secretion ◽  
Carboxy Terminal Region ◽  
Assay Methods ◽  
Low Levels ◽  
Carboxy Terminal

ABSTRACT The presence of an hCG-like material in urinary and pituitary extracts and plasma obtained from non-pregnant subjects was investigated. Two assay methods were used to detect this material following fractionation of pituitary and urinary extracts by gel filtration (Ultrogel AcA 54) and/or isoelectrofocusing: a) a radioimmunoassay employing an antiserum raised against a specific sequence of the carboxy terminal region (residues 115– 145) of the β-subunit of hCG, and b) an in vitro bioassay method which measures both hLH and hCG activities. The fractionation procedures employed provide a satisfactory separation of highly purified hCG and hLH preparations. In the pituitary and urinary extracts hCGβ-peptide-like immunoactive (PIA) material was found consistently, which co-eluted with iodinated hCG following gel filtration and possessed pI values similar to those of hCG when subjected to isoelectrofocusing. The PIA material also exhibited in vitro biological activity similar to that shown by hLH and hCG. Detectable levels of immunoactive material were also found in plasma; however, the plasma levels of this PIA material were not influenced by classical endocrine measures such as the stimulation or inhibition of gonadotrophin secretion. The low levels of this material in plasma precluded its further characterization by gel filtration or electrofocusing. Whereas the present data and those reported by other investigators seem to suggest the presence of some hCG-like material in urinary and pituitary extracts and possibly in plasma of non-pregnant subjects, it is emphasized that the available evidence is not sufficiently conclusive to exclude other interpretations as to the nature of this material.

A single amino acid residue replacement in the β subunit of human chorionic gonadotrophin results in the loss of biological activity

1992 ◽  
Vol 8 (1) ◽  
pp. 87-89 ◽  
Author(s):  
F. Chen ◽  
D. Puett
Keyword(s):  
Amino Acid ◽  
Amino Acid Residue ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Amino Acid Sequences ◽  
Single Amino Acid ◽  
Β Subunit ◽  
Single Amino Acid Residue

ABSTRACT The heterodimer, human chorionic gonadotrophin (hCG), contains an a subunit that is common to the glycoprotein hormones and a hormone-specific β subunit. A comparison of all known β amino acid sequences shows that an aspartic acid at position 99 (with the numbering scheme for hCG-β) is one of the seven non-Cys invariant residues. Using site-directed mutagenesis we have replaced hCG-β Asp99 with Arg. Chinese hamster ovary cells, containing a stably integrated gene for bovine a subunit, were transiently transfected with plasmids containing wild-type and mutant hCG-β cDNAs. The Arg99 β mutant associated with the a subunit, but the resulting heterodimer failed to enhance intracellular cyclic AMP production in a gonadotrophin-responsive transformed murine Leydig cell line. Thus, a single amino acid residue replacement in this glycosylated heterodimer containing 237 amino acid residues is sufficient to abolish activity.

RELATIONSHIPS BETWEEN PHYSICO-CHEMICAL IMMUNOLOGICAL AND BIOLOGICAL PROPERTIES OF HUMAN CHORIONIC GONADOTROPHIN

1971 ◽  
Vol 67 (3) ◽  
pp. 445-456 ◽  
Author(s):  
D. L. Matthies ◽  
P. Petrusz ◽  
E. Diczfalusy
Keyword(s):  
Follicle Stimulating Hormone ◽  
Gel Filtration ◽  
Biological Properties ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Gel Filtration Chromatography ◽  
Physico Chemical ◽  
Immunological Test ◽  
Stimulating Hormone

ABSTRACT Purified human chorionic gonadotrophin (HCG) preparations were chromatographed on Sephadex G-100 and the distribution of the hormone on the chromatogram was studied by an immunological test and by bioassay. Each preparation studied showed evidence of inhomogeneity in terms of the degree to which it was retarded on the gel bed, but the type of inhomogeneity was variable. By the use of gel filtration chromatography it was possible to separate HCG molecules devoid of detectable follicle stimulating hormone (FSH)-like activity from molecules which possessed FSH-like activity. Evidence is presented which indicates that at least some physico-chemical manipulations utilized in the purification of HCG from urine may introduce artifacts.

scholarly journals Structural and functional analysis of rare missense mutations in human chorionic gonadotrophin β-subunit

2012 ◽  
Vol 18 (8) ◽  
pp. 379-390 ◽  
Author(s):  
Liina Nagirnaja ◽  
Česlovas Venclovas ◽  
Kristiina Rull ◽  
Kim C. Jonas ◽  
Hellevi Peltoketo ◽  
...  
Keyword(s):  
Functional Analysis ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Missense Mutations ◽  
Β Subunit

Total amounts of circulating human chorionic gonadotrophin α and β subunits can be assessed throughout human pregnancy using immunoradiometric assays calibrated with the unaltered and thermally dissociated heterodimer

1994 ◽  
Vol 140 (3) ◽  
pp. 513-520 ◽  
Author(s):  
A-M Nagy ◽  
D Glinoer ◽  
G Picelli ◽  
J Delogne-Desnoeck ◽  
B Fleury ◽  
...  
Keyword(s):  
Early Pregnancy ◽  
Thermal Dissociation ◽  
Heat Exposure ◽  
Free Fraction ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Β Subunit ◽  
Human Pregnancy ◽  
Molar Basis ◽  
Α And Β Subunits

Abstract The aim of the present study was to determine the variations in the balance between total (free plus combined) circulating α and β subunits of human chorionic gonadotrophin (hCG) throughout human pregnancy. The equivalence between the International Units (IU) of hCG (IRP 75/537) and those assigned to the α (IRP 75/569) and β (IRP 75/551) free subunits was experimentally determined by using intact and thermally dissociated hCG. Heat exposure (2 min at 100 °C) of hCG preparations resulted in a complete dissociation of hCG into free, soluble and intact α and β subunits. The hCG and α and β subunit contents of unaltered and heated hCG preparations were assessed by specific immunoradiometric assays. The amount of immunoreactive subunits dissociated by heat from hCG could then be evaluated on a molar basis. Circulating hCG and its free α and β subunits were immunoassayed in 836 blood samples collected from healthy pregnant women at different gestational ages. After conversion of hCG and its subunits into a common IU system, the gestational profiles of the total amounts (free plus combined) of α- and βhCG subunits increased together and peaked at 9–10 weeks of gestation. Thereafter, total α and β subunits decreased and subsequently remained stable until term. The decline in total αhCG subunit was less marked than that of total βhCG subunit. The α- to βhCG ratio was equimolar until 10 weeks of gestation when it increased almost fourfold until term (P<0·0001). Finally, the free fraction of the total circulating αhCG subunit represented 5–7% in early pregnancy but reached 60–70% in the last trimester (P<0·0001). In contrast, the free fraction of the total βhCG subunit decreased slightly from 4–5% of total β subunit in early pregnancy to 2–3% at term (P<0·0001). The present study suggests that thermal dissociation of hCG is a useful method with which to calibrate immunoassays on a molar basis in order to assess circulating levels of the heterodimer and its subunits. Journal of Endocrinology (1994) 140, 513–520

The molecular basis for epitopes on the free β-subunit of human chorionic gonadotrophin (hCG), its carboxyl-terminal peptide and the hCGβ-core fragment

1994 ◽  
Vol 141 (1) ◽  
pp. 153-162 ◽  
Author(s):  
S Dirnhofer ◽  
S Madersbacher ◽  
J-M Bidart ◽  
P B W Ten Kortenaar ◽  
G Spöttl ◽  
...  
Keyword(s):  
Amino Acid ◽  
Molecular Basis ◽  
Tertiary Structure ◽  
Solid Phase ◽  
Critical Role ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Antigenic Determinants ◽  
Β Subunit ◽  
Carboxyl Terminal

Abstract The molecular basis for antigenic determinants on the free β-subunit of human chorionic gonadotrophin (hCGβ), its carboxyl-terminal peptide (hCGβCTP) and the hCGβcore fragment (hCGβcf) was elucidated by means of monoclonal antibodies (MCAs). The objective of the present study was to resolve the antigenic topography of these three molecules in terms of epitope identification at different levels of structural organization as well as analysis of their spatial arrangement. An hCGβcf preparation, a synthetic peptide corresponding to the hCGβCTP (β109–145), overlapping synthetic peptides spanning the entire amino acid sequence of hCGβ, and a reduced and alkylated hCGβ preparation were assayed in a solid-phase one-site enzyme-linked immunoassay and in a solublephase direct-binding radioimmunoassay (RIA) or competitive RIA. The antigenic topography was mapped by incorporating the MCAs into two-site binding assays. On the surface of free hCGβ, nine different epitopes (β1–β9), arranged in three spatially distinct domains, could be distinguished. Epitopes β1–β7 were located in a single large domain on both hCGβ and the hCGβcf whereas hCGβCTP contained two topographically distant determinants, designated β8 and β9 respectively. All but the two epitopes located on hCGβCTP (β8 and β9) were destroyed by reducing and alkylating hCGβ, suggesting that most antigenic determinants are predominantly non-contiguous and require an intact tertiary structure whereas the molecular structure of hCGβCTP is linear. At a molecular level, amino acid residues spanning hCGβ 45–52, hCGβ 137–144 and hCGβ 113–116 contributed to the formation of epitopes β5, β8 and β9 respectively. We have also shown that the hCGβcf represents the immunodominant part of the free β-subunit of hCG, containing seven mainly conformationally determined epitopes, one of which has a share of the sequence β45–52. The hCGβCTP does not play a critical role in the immunologically important tertiary structure of hCGβ and was itself found to be a predominantly continuous sequence also within the native hormone, expressing two spatially distant antigenic determinants located within residues β113–116 and β137–144 respectively. Journal of Endocrinology (1994) 141, 153–162

Fate of receptor-bound human chorionic gonadotrophin in pseudopregnant rat ovaries perfused in vitro

1985 ◽  
Vol 109 (1) ◽  
pp. 115-121
Author(s):  
Hannu Rajaniemi ◽  
Jan Sogn ◽  
Paul Holmes ◽  
Björn Källfelt ◽  
Per Olof Janson
Keyword(s):  
Molecular Weight ◽  
Histological Examination ◽  
Gel Filtration ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Cell Periphery ◽  
Small Molecular Weight ◽  
Immunohistochemical Studies

Abstract. Pseudopregnant rats were injected with [125I] hCG, anaesthesized 1 h later and after cannulation of the aorta the ovaries were isolated and perfused with Gey & Gey buffer containing 0.2% BSA. The release of radioactivity was monitored for 2 h and analyzed by gel filtration. Five to ten per cent of the radioactivity was released within 2 h and represented small molecular weight peptides and iodotyrosine and [125I]hCG. Analysis of the ovarian radioactivity prior to and after perfusion revealed that virtually all hCG was receptor-bound. Loading the medium with unlabelled hCG displaced [125I]hCG from the receptor but did not enhance its degradation. Histological examination showed that the ovarian tissues were still intact after the 2 h perfusion. Immunohistochemical studies revealed a localization of the hCG at the cell periphery both prior to and after perfusion. These results provide evidence showing that the rate of internalization of receptor-hCG complexes in rat luteal cells is slow in vivo.

A novel form of ectopic human chorionic gonadotrophin β-subunit in the serum of a woman with epidermoid cancer

1985 ◽  
Vol 107 (3) ◽  
pp. 403-408 ◽  
Author(s):  
S. B. Nagelberg ◽  
L. A. Cole ◽  
S. W. Rosen
Keyword(s):  
Molecular Weight ◽  
Unknown Origin ◽  
Apparent Molecular Weight ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Size Difference ◽  
Gel Chromatography ◽  
Β Subunit ◽  
Peanut Agglutinin ◽  
Pregnancy Urine

ABSTRACT A novel form of free human chorionic gonadotrophin β-subunit (hCGβ) was found in serum from ElBre, a woman with epidermoid carcinoma of unknown origin. ElBre hCGβ was larger than standard (pregnancy urine) hCGβ when analysed by gel chromatography (apparent molecular weight 54 000 vs 44000). This size difference appeared to be due to a larger carboxyterminal extension (CTE) of ElBre hCGβ since thermolysin cleavage of the CTE from standard hCGβ and Elbre hCGβ yielded core products of the same size. Oligosaccharides, O-linked to serine or threonine, were present in ElBre hCGβ, presumably on its CTE as judged by the complete binding of desialylated ElBre hCGβ to immobilized peanut agglutinin (this lectin is specific for terminal galactose linked β1 → 3 to N-acetylgalactosamine, a disaccharide exposed after desialylation of the O-linked oligosaccharides of standard hCGβ). ElBre hCGβ, however, was incompletely recognized by antisera specific for the CTE of standard hCGβ, especially the carbohydrate-sensitive antiserum R141. The O-linked oligosaccharides of standard hCGβ are heterogeneous in size; 13% are of the largest (hexasaccharide) form. In contrast, over 50% of the O-linked oligosaccharides in hCGβ from the JAr choriocarcinoma cell line are hexasaccharides. Like desialylated ElBre hCGβ, desialylated JAr hCGβ bound completely to peanut agglutinin, but was incompletely recognized by antisera to the hCGβ-CTE. Furthermore, JAr hCGβ was intermediate in size between standard hCGβ and ElBre hCGβ when analysed by gel chromatography (apparent molecular weight 49 000). Thus, we propose that ElBre hCGβ had an even higher proportion of large O-linked oligosaccharides than had JAr hCGβ. Moreover, the N-linked oligosaccharides of ElBre hCGβ differed from standard hCGβ; only 55% of ElBre hCGβ bound to Concanavalin A versus 89% of standard hCGβ. These data further support the concepts of aberrant glycosylation by neoplastic tissues and carbohydrate heterogeneity of hCGβ produced by various tissues. J. Endocr. (1985) 107, 403–408

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