Reversed-phase high-performance liquid chromatography of human thyroid-stimulating hormone

Analysis of intact human follicle-stimulating hormone preparations by reversed-phase high-performance liquid chromatography

A reversed-phase high-performance liquid chromatography (RP-HPLC) method for the qualitative and quantitative analysis of intact human follicle-stimulating hormone (hFSH) was established and validated for accuracy, precision and sensitivity. Human FSH is a dimeric glycoprotein hormone widely used as a diagnostic analyte and as a therapeutic product in reproductive medicine. The technique developed preserves the protein integrity, allowing the analysis of the intact heterodimeric form rather than just of its subunits, as is the case for the majority of the conditions currently employed. This methodology has also been employed for comparing the relative hydrophobicity of pituitary, urinary and two Chinese hamster ovary (CHO)-derived hFSH preparations, as well as of two other related glycoprotein hormones of the anterior pituitary: human thyroid-stimulating hormone (hTSH) and human luteinizing hormone (hLH). The least hydrophobic of the three glycohormones analyzed was hFSH, followed by hTSH and hLH. A significant difference (p<0.005) was observed in t(R) between the pituitary and recombinant hFSH preparations, reflecting structural differences in their carbohydrate moieties. Two main isoforms were detected in urinary hFSH, including a form which was significantly different (p<0.005) from the pituitary and recombinant preparations. The linearity of the dose-response curve (r=0.9965, n=15) for this RP-HPLC methodology, as well as an inter-assay precision of less than 4% for the quantification of different hFSH preparations and a sensitivity of the order of 40 ng, were demonstrated. The chromatographic behaviour and relative hydrophobicity of the individual subunits of the pituitary and recombinant preparations were also analyzed. Furthermore, the molecular mass of individual hFSH subunits and of the heterodimer were simultaneously determined by matrix-assisted laser desorption ionization time-of-flight mass spectral analysis (MALDI-TOF-MS). The present methodology represents, in our opinion, an essential tool for the characterization and quality control of this hormone, that is not yet described in the main pharmacopoeias.

Determination of Chinese hamster ovary cell-derived recombinant thyrotropin by reversed-phase liquid chromatography

A reversed-phase high-performance liquid chromatography (RP-HPLC) methodology for the qualitative and quantitative analysis of human thyrotropin (hTSH) in CHO cell conditioned medium and in purified preparations has been set up and validated for accuracy, precision and sensitivity. A recovery test indicated a bias of less than 2% and intra-day and inter-day quantitative determinations presented relative standard deviations (RSD) always <7%, while sensitivity was 0.2 microg (RSD=5.6%). The novel methodology was applied to the study of the best cultivation conditions and was able to detect a significant difference in retention time (t(R)) between pituitary and recombinant hTSH, probably reflecting the influence of the heterogeneity of the carbohydrate moiety on the hydrophobic properties of the molecule.

High-performance liquid chromatography of human glycoprotein hormones

The chromatographic behavior of the glycoprotein hormones from human pituitary glands and of placental origin [thyroid-stimulating hormone, luteinizing hormone and chorionic gonadotropin (CG)] was studied. It was shown that hydrophobic interaction chromatography on a microparticulate packing and anion-exchange HPLC can be applied for the purification of these hormones. Reversed-phase HPLC on wide-pore C4-bonded silica at neutral pH can be applied for the determination of the above hormones and for the isolation of pure CG and its subunits.

Separation of human glycoprotein hormones and their subunits by reversed-phase liquid chromatography

Separation of human pituitary follicle-stimulating hormone (FSH), luteinizing hormone (LH) and thyroid-stimulating hormone (TSH) was effected on a micro-scale by reversed-phase high-performance liquid chromatography (HPLC) on a SynChropak C1 column in series with a Vydac C4 column using a linear gradient of acetonitrile in 0.1 M triethylamine phosphate buffer at pH 6.5. Chromatography on the C4 column alone caused partial dissociation of FSH into its subunits, whereas LH and TSH remained intact. Good yields of the separated subunits were obtained after prior dissociation of each hormone, and the results show that reversed-phase HPLC is useful for the analytical and preparative separation of these structurally related hormones and their subunits.

Protein purification

This monograph summarizes recent developments in the purification and analysis of natural and recombinant proteins. The basic strategies employed in protein purification are reviewed with regards to the characteristics of the protein of interest that may aid its isolation, choice of the starting material, and use of denaturants. Preparation of cell-free extracts followed by bulk precipitation and/or phase partition constitute the initial steps of many purification schemes. Chromatographic methods (size exclusion, ion exchange, hydroxylapatite, reversed phase, hydrophobic interaction and affinity based) utilizing either traditional, low pressure or high-performance liquid chromatography instrumentation are discussed. Electrophoretic techniques used to analyze the homogeneity of the protein product include SDS-PAGE, isotachophoresis, IEF and two dimensional gel electrophoresis.

Preparative reversed-phase high-performance liquid chromatography of iodinated insulin retaining full biological activity

Insulin monoiodinated in Tyr A14, A19, B16 and B26 can be separated from insulin and diiodoinsulins using reversed-phase high-performance liquid chromatography on LiChrosorb RP-18 columns. Monoiodoinsulins with high and low specific activities were isolated from a number of buffer systems without any reduction in binding affinity and biological activity in isolated rat fat cells. The reason for the previously observed reduction in the binding affinity was probably column bleeding, i.e., chemical degradation of the column support.

Pattern of immunoreactivity after reverse-phase high performance liquid chromatography of ovine lutropin at different pH

Unlabelled and radioiodinated ovine lutropin (oLH) was fractionated using reverse-phase high pressure liquid chromatography, employing a 5 micron Spherisorb C18 column. Following chromatography of unlabelled oLH at pH 3.3, 4.3 and 5.3, all eluted fractions were tested by radioimmunoassay of oLH, oLH alpha and oLH beta. Regardless of pH, the material corresponding to the first peak contained only alpha-subunit immunoreactivity. With increasing pH, the oLH alpha, oLH and oLH beta immunoreactivity separated into two groups of fractions. The retention times of the radioiodinated alpha- and beta-subunits of oLH corresponded to those of the first (descending part) and last peaks from unlabelled oLH, respectively. Following chromatography of radioiodinated oLH at pH 3.3, 5.3 and 6.5, all eluted fractions were analyzed using antiserum against either alpha- or beta-subunits of oLH. At pH 3.3 two radioactive peaks were detected: the first corresponded to the fraction with maximum binding to alpha-subunit antiserum, and the second corresponded to the fraction with maximum binding to beta-subunit antiserum. At pH 5.3 and 6.5, maximum radioactivity occurred in conjunction with maximum binding to both antisera. A free alpha-subunit in the radioiodinated oLH was even detected after chromatography at pH 6.5.

The effect of castration and androgen replacement on rat pituitary follicle stimulating hormone investigated by reversed-phase high performance liquid chromatography

Rat follicle stimulating hormone (rFSH) was analysed in extracts of rat anterior pituitary using a newly developed separation method of reversed-phase high performance liquid chromatography (RP-HPLC) and post-column detection of immunoreactivity (rFSH-IR) by radioimmunoassay (RIA) or immunoprecipitation with a specific anti-rFSH antibody. Good separation of rFSH was achieved on a Waters Radial-Peak 8MBC18 cartridge with a linear (60 min) gradient from 10-60% acetonitrile at constant 0.1% trifluoroacetic acid concentration. The elution profiles of radioiodinated purified rFSH [(125I)rFSH] as well as extracts of adult male and female rat pituitaries contained two main immunoreactive components (peaks 1 and 2) which eluted at 16-17 min and 21 min respectively. In the (125I)rFSH elution profile, the peaks of immunobinding corresponded to two major peaks of radioactivity. The male pituitary showed greater binding to anti-rFSH-serum of peak 1 and 2 eluate compared to female pituitary. At day 20 after orchidectomy, the amount of immunoreactive rFSH (rFSH-IR) increased in both peaks (by 30% in peak 1 and 180% in peak 2); however, the rFSH-IR level in peak 2 appeared to be more variable compared with that in peak 1. Subcutaneous implantation of 5 mg or 15 mg of dihydrotestosterone (DHT) at the time of orchidectomy prevented the post-castration elevation of rFSH-IR at 10 and 20 days after surgery. The precise nature and physiological significance of the two elution peaks are not clear at this time; however, only peak 2 showed immunoreactivity with anti-rLH-alpha-subunit antibody (AFP 87713681) and the elution time of peak 2 coincided with that of (125I) rLH-alpha subunit (AFP-7264 B).(ABSTRACT TRUNCATED AT 250 WORDS)

Reversed-phase high-performance liquid chromatography of human haemoglobin chains

A reversed-phase high-performance liquid chromatographic method for the separation of human haemoglobin chains has been devised. Using a LiChrospher 100 CH-8/2 column and a ternary eluent (acetonitrile-methanol-0.155 M NaCl, pH 2.7) improved resolution was achieved between (delta beta) Lepore, beta A, beta S, alpha, G gamma and A gamma chains within a 60-min linear gradient. The A gamma T chain can also be separated by increasing the gradient time and decreasing the flow-rate. Silanophilic interactions play an important role in the retention mechanism, and NaCl addition was necessary in order to suppress adsorption on free silanols. Increasing the methanol concentration to 10% caused a slight increase in chain retention, probably owing to solvation of the stationary phase. The recovery was 82% and the reproducibility of retention times was as good as +/- 1.5%. Quantitation of chains is likely to be possible by peak area measurement. Owing to its sensitivity, the proposed method may be useful in the diagnosis of haemoglobinopathies and in the study of haemoglobin variants.

Subunits of bovine lutropin. Hormonal and immunological activity after separation with reversed-phase high-performance liquid chromatography

By means of reversed-phase high-performance liquid chromatography, we have fractionated bovine lutropin (LH) standard preparations. The highly purified NIAMDD-bLH-4 was fractionated into two components, while the less pure NIH-LH-B9 revealed three distinct peaks. The eluted material was further characterized by in vitro bioassay and by homologous radioimmunoassay for bovine LH, ovine LH-alpha and ovine LH-beta subunits. The material with the shortest retention time possessed almost no LH-activity and showed a displacement curve nearly identical with that of the ovine LH-alpha subunit. The material corresponding to the second peak exhibited 6% of the original LH-activity, and its immunoreactivity was equal to that of the ovine LH-beta subunit. Furthermore, the fractions supposed to contain the alpha and the beta subunits were rechromatographed and their aminoacid contents analyzed. The results show close similarities between the rechromatographed fractions and the pure subunits.

Biologic activity of human chorionic gonadotropin following reversed-phase high-performance liquid chromatography

Human chorionic gonadotropin (hCG) was analyzed by reversed-phase high-performance liquid chromatography (HPLC) using mobile phases previously described in the literature, as well as newly developed solvent systems. Fractions of hCG collected following reversed-phase HPLC were bioassayed by activation of adenylate cyclase to determine their biologic potencies. hCG retained only 10-60% of its biologic activity following reversed-phase HPLC, depending on the chromatographic conditions employed. A portion of the reduced biologic activity was attributed to dissociation of the alpha- and beta-subunits of hCG at the low pH of the mobile phases, since neutralization of the pH prior to lyophilization and bioassay increased the biologic potency of the chromatographed hormone. The remaining loss in biologic activity is presumably due to organic solvent denaturation.