Purification and properties of choriogonadotropin from human term placenta

Identification and Relative Quantification of hFSH Glycoforms in Women's Sera via MS-PRM-Based Approach

Follicle-stimulating hormone (FSH) is a glycohormone synthesized by adenohypophysis, and it stimulates ovulation in women and spermatogenesis in men by binding to its receptor (FSHR). FSHR is involved in several mechanisms to transduce intracellular signals in response to the FSH stimulus. Exogenous FSH is currently used in the clinic for ovarian hyperstimulation during in vitro fertilization in women, and for treatment of infertility caused by gonadotropin deficiency in men. The glycosylation of FSH strongly affects the binding affinity to its receptor, hence significantly influencing the biological activity of the hormone. Therefore, the accurate measurement and characterization of serum hFSH glycoforms will contribute to elucidating the complex mechanism of action by which different glycoforms elicit distinct biological activity. Nowadays ELISA is the official method with which to monitor serum hFSH, but the test is unable to distinguish between the different FSH glycovariants and is therefore unsuitable to study the biological activity of this hormone. This study presents a preliminary alternative strategy for identifying and quantifying serum hFSH glycoforms based on immunopurification assay and mass spectrometry (MS), and parallel reaction monitoring (PRM) analysis. In this study, we provide an MS–PRM data acquisition method for hFSH glycopeptides identification with high specificity and their quantification by extracting the chromatographic traces of selected fragments of glycopeptides. Once set up for all its features, the proposed method could be transferred to the clinic to improve fertility treatments and follow-ups in men and women.

Molecular heterogeneity of human chorionic gonadotropin and its subunits in testicular cancer

The secretion of human chorionic gonadotropin and its subunits was examined by a heterologous hCG/hCG-beta radioimmunoassay and homologous radioimmunoassays of the alpha- and beta-subunit in patients with nonseminomatous testicular germ cell tumors. Of 53 patients, 32 (60%) had elevated levels of hCG (9 IU/l-4.5 million IU/l), 12 (23%) elevated serum concentrations of hCG-beta (20-286 micrograms/l) and 8 (15%) of hCG-alpha (14-498 micrograms/l). A selective elevation of hCG-subunits without the hormone was never observed. Serum concentrations of hCG-beta were to low to interfere in the heterologous radioimmunoassay using 125I-hCG and anti-hCG-beta antiserum. Gelfiltration of patient's sera (n = 5) on Ultrogel AcA 44 column confirmed the secretion of free subunits and additionally a high molecular form of hCG-beta (70,000) in three of five serum specimens. Furthermore, the molecular heterogeneity of hCG and hCG-subunits was examined by affinity chromatography on Concanavalin A (Con A)-sepharose. There was a significant difference of Con A nonreactive hCG and hCG-alpha between patients with testicular cancer (hCG:2-82%; mean, 22%; n = 7; hCG-alpha: 11-61%; mean, 31%; n = 7) and pregnant women (hCG: 0%; n = 3; hCG-alpha: 0-13%; mean, 6%; n = 5). Con A nonreactive and reactive hCG of patients with cancer revealed similar binding in a radioreceptor gonadotropin assay. The Con A nonreactive fraction of the beta-subunit was determined to be 20-73% (mean, 50%; n = 6) in serum samples of patients with testicular cancer and did not differ from the percentage in pregnant women (29-67%; mean, 46%; n = 4). The lectin binding heterogeneity of hCG and hCG-alpha indicate structural variations in the carbohydrate chains. It is assumed that Con A nonreactive hCG and hCG-alpha are directly liberated by nonsecretory mechanism from tumor cells into the circulation. Determination of hCG released by cell damage may have clinical significance in patients with testicular cancer under chemotherapy.

Isolation of hormonal proteins and antibodies by affinity chromatography

The versatile technique of biospecific affinity chromatography has found application in the purification as well as isolation of many hormones and their antibodies. Hormones can be effectively concentrated from very dilute solutions such as urine or other fluids including culture media. The technique may be expected to have a big impact in the isolation of hormone receptors. Its limitations are not unique to the above macromolecules but extend to the general method itself, the most important being the development of stable immobilized ligands and efficient but still mild solvent systems for elution. The use of dilute ammonia solutions at low temperatures has been quite successful for displacing either the hormone or the antibody.

Purification and characterization of choriogonadotropin from hydatidiform mole

Human choriogonadotropin (HCG) of high immunoactivity was isolated from hydatidiform mole by acid and salt precipitation, immunoaffinity and DEAE-Sephadex chromatography. Polyacrylamide gel electrophoresis, immunodiffusion, immunoelectrophoresis and N-terminal amino acid analyses showed that the product obtained is essentially homogeneous. Molar HCG was found to resemble HCG from urine of normal pregnant women in amino acid composition bu to differ from it in having a lower content of mannose and N-acetylglucosamine.