HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (11) Citing Articles via Google Scholar Google Scholar Articles by Jacoby, E. S. Articles by Iles, R. K. Search for Related Content PubMed PubMed Citation Articles by Jacoby, E. S. Articles by Iles, R. K. Related Collections Proteomics and Protein Markers Endocrinology and Metabolism

Determination of the Glycoforms of Human Chorionic Gonadotropin ß-Core Fragment by Matrix-assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

¹ The Williamson Laboratory, Department of Obstetrics and Gynaecology, St. Bartholomew’s & the Royal London School of Medicine and Dentistry, West Smithfield, London EC1A 7BE, United Kingdom.

² The Drug Control Centre, King’s College London, Franklin-Wilkins Building, 150 Stamford St., London SE1 8WA, United Kingdom.
^a Author for correspondence. Fax 44-020-7601-7050; e-mail r.k.iles{at}mds.qmw.ac.uk

Background: Metabolism of human chorionic gonadotropin (hCG) in the serum and kidney yields the terminal urinary product hCG ß-core fragment (hCGßcf), comprising two disulfide-linked peptides (ß6-ß40 and ß55-ß92) of which one (ß6-ß40) retains truncated N-linked sugars. Hyperglycosylated hCGßcf may indicate choriocarcinoma or Down syndrome, but the glycosylation profile of hCGßcf has not been thoroughly evaluated.

Methods: hCGßcf, purified from pregnancy urine, was reduced by "on-target" dithiothreitol (DTT) reduction and analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The mass ([M+H]⁺) of the primary sequence of the glycosylated peptide ß6-ß40 was subtracted from the m/z values of the discrete peaks observed to give the masses of the carbohydrate moieties. Carbohydrate structure was predicted by sequentially subtracting the masses of the monosaccharide residues corresponding to N-linked carbohydrates of the hCG ß-subunit reported in the literature.

Results: Mass spectra of hCGßcf revealed a broad triple peak at m/z 8700–11300. After reduction, the triple peak was replaced by a discrete set of peaks between m/z 4156 and 6354. A peak at m/z 4156.8 corresponded to the nonglycosylated peptide (ß55-ß92). The remaining nine peaks indicated that urinary hCGßcf comprises a set of glycoforms smaller and larger than the trimannosyl core.

Conclusions: hCGßcf comprises a wider set of glycoforms than reported previously. Peaks of highest mass indicate evidence of hyperglycosylated carbohydrate moieties. The data support previous reports that hCGßcf oligosaccharides lack sialic acid and galactose residues. No indication was found of a ß6-ß40 peptide that was entirely devoid of carbohydrate.

The following articles in journals at HighWire Press have cited this article:

				L. Valmu, H. Alfthan, K. Hotakainen, S. Birken, and U.-H. Stenman Site-specific glycan analysis of human chorionic gonadotropin {beta}-subunit from malignancies and pregnancy by liquid chromatography--electrospray mass spectrometry Glycobiology, December 1, 2006; 16(12): 1207 - 1218. [Abstract] [Full Text] [PDF]

				U.-H. Stenman, A. Tiitinen, H. Alfthan, and L. Valmu The classification, functions and clinical use of different isoforms of HCG Hum. Reprod. Update, November 1, 2006; 12(6): 769 - 784. [Abstract] [Full Text] [PDF]

				A. Gervais, Y.-a. Hammel, S. Pelloux, P. Lepage, G. Baer, N. Carte, O. Sorokine, J.-m. Strub, R. Koerner, E. Leize, et al. Glycosylation of human recombinant gonadotrophins: characterization and batch-to-batch consistency Glycobiology, March 1, 2003; 13(3): 179 - 189. [Abstract] [Full Text] [PDF]