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. 1976 May 1;155(2):303–315. doi: 10.1042/bj1550303

The structures of the carbohydrate moieties of the alpha subunit of human chorionic gonadotrophin.

J F Kennedy, M F Chaplin
PMCID: PMC1172836  PMID: 938481

Abstract

The alpha subunit of human chorionic gonadotrophin was reduced with dithiothreitol followed by carboxymethylation with iodoacetic acid. The modified glycoprotein was hydrolysed with trypsin to give various peptides, the identities of which were established, and glycopeptides. The glycopeptides were separated by gel filtration and ion-exchange chromatography; they were subjected to component analysis and were found to represent the two carbohydrate moieties in the parent glycoprotein. Sequential removal with glycoside hydrolases of monosaccharide units from the glycopeptides demonstrated (1) that galactose, mannose, glucosamine (2-amino-2-deoxyglucose) and neuraminic acid (5-amino-3,5-dideoxy-glycero-galacto-2-nonulosonic acid) residues possess the D configurations, (2) that the glucosamine units are N-acetylated and (3) the order of the monosaccharide units in the chain, the neuraminic acid units being furthest from the peptide backbone of the subunit and substituting the D-galactose units. Methylation analysis of the glycopeptides by adaptation of the Hakomori technique demonstrated that: (4) D-galactose, D-mannose and N-acetylglucosamine (2-acetamido-2-deoxy-D-glucose) units exist in the pyranose forms; (5) the D-galactopyranose units are linked in the 1 and 6 positions; (6) the D-mannopyranose units exist in several forms, one in a terminal non-reducing position, one as 1,2-linked residues and some as 1,6-linked branch points; (7) the N-acetylglucosamine units are 1,6-linked. On the basis of the results of methylation and enzymic analysis, structures are proposed for the carbohydrate moieties and the assignments are compared with other data previously obtained by periodate-oxidation studies [Kennedy et al. (1974) Carbohydr. Res. 36, 369-377].

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Ashitaka Y., Tokura Y., Tane M., Mochizuki M., Tojo S. Studies on the biochemical properties of highly purified HCG. Endocrinology. 1970 Aug;87(2):233–244. doi: 10.1210/endo-87-2-233. [DOI] [PubMed] [Google Scholar]
  2. Bahl O. P. Human chorionic gonadotropin. I. Purification and physicochemical properties. J Biol Chem. 1969 Feb 25;244(4):567–574. [PubMed] [Google Scholar]
  3. Bahl O. P. Human chorionic gonadotropin. II. Nature of the carbohydrate units. J Biol Chem. 1969 Feb 25;244(4):575–583. [PubMed] [Google Scholar]
  4. Bell J. J., Canfield R. E., Sciarra J. J. Purification and characterization of human chorionic gonadotropin. Endocrinology. 1969 Feb;84(2):298–307. doi: 10.1210/endo-84-2-298. [DOI] [PubMed] [Google Scholar]
  5. Bellisario R., Carlsen R. B., Bahl O. P. Human chorionic gonadotropin. Linear amino acid sequence of the alpha subunit. J Biol Chem. 1973 Oct 10;248(19):6796–6809. [PubMed] [Google Scholar]
  6. Carlsen R. B., Bahl O. P., Swaminathan N. Human chorionic gonadotropin. Linear amino acid sequence of the beta subunit. J Biol Chem. 1973 Oct 10;248(19):6810–6827. [PubMed] [Google Scholar]
  7. Chambers R. E., Clamp J. R. An assessment of methanolysis and other factors used in the analysis of carbohydrate-containing materials. Biochem J. 1971 Dec;125(4):1009–1018. doi: 10.1042/bj1251009. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Cornell J. S., Pierce J. G. The subunits of human pituitary thyroid-stimulating hormone. Isolation, properties, and composition. J Biol Chem. 1973 Jun 25;248(12):4327–4333. [PubMed] [Google Scholar]
  9. HAKOMORI S. A RAPID PERMETHYLATION OF GLYCOLIPID, AND POLYSACCHARIDE CATALYZED BY METHYLSULFINYL CARBANION IN DIMETHYL SULFOXIDE. J Biochem. 1964 Feb;55:205–208. [PubMed] [Google Scholar]
  10. KOSTKA V., CARPENTER F. H. INHIBITION OF CHYMOTRYPSIN ACTIVITY IN CRYSTALLINE TRYPSIN PREPARATIONS. J Biol Chem. 1964 Jun;239:1799–1803. [PubMed] [Google Scholar]
  11. Kennedy J. F., Butt W. R. Periodate oxidation studies of human pituitary follicle-stimulating hormone. Biochem J. 1969 Nov;115(2):225–229. doi: 10.1042/bj1150225. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Kennedy J. F., Chaplin M. F., Stacey M. Periodate oxidation, acid hydrolysis, and structure-activity relationships of human-pituitary, follicle-stimulating hormone and human chorionic gonadotrophin. Carbohydr Res. 1974 Sep;36(2):369–377. doi: 10.1016/s0008-6215(00)83058-x. [DOI] [PubMed] [Google Scholar]
  13. Kennedy J. F., Chaplin M. F. Structural investigation of the carbohydrate element of human pituitary follicle-stimulating hormone by methylation analysis. Biochem J. 1972 Nov;130(2):417–423. doi: 10.1042/bj1300417. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Kennedy J. F., Doyle C. E. Active, water-insoluble derivatives of D-glucose oxidase and alginic acid, chitin, and Celite. Carbohydr Res. 1973 May;28(1):89–92. doi: 10.1016/s0008-6215(00)82860-8. [DOI] [PubMed] [Google Scholar]
  15. Kennedy J. F. The relationship of the activity of gonadotrophins to their structures. Endocrinol Exp. 1973;7(1):5–17. [PubMed] [Google Scholar]
  16. Li S. C., Li Y. T. Studies on the glycosidases of jack bean meal. 3. Crystallization and properties of beta-N-acetylhexosaminidase. J Biol Chem. 1970 Oct 10;245(19):5153–5160. [PubMed] [Google Scholar]
  17. Li Y. T. Studies on the glycosidases in jack bean meal. I. Isolation and properties of alpha-mannosidase. J Biol Chem. 1967 Dec 10;242(23):5474–5480. [PubMed] [Google Scholar]
  18. Morgan F. J., Canfield R. E., Vaitukaitis J. L., Ross G. T. Properties of the subunits of human chorionic gonadotropin. Endocrinology. 1974 Jun;94(6):1601–1606. doi: 10.1210/endo-94-6-1601. [DOI] [PubMed] [Google Scholar]
  19. Pierce J. G., Bahl O. P., Cornell J. S., Swaminathan N. Biologically active hormones prepared by recombination of the alpha chain of human chorionic gonadotropin and the hormone-specific chain of bovine thyrotropin or of bovine luteinizing hormone. J Biol Chem. 1971 Apr 10;246(7):2321–2324. [PubMed] [Google Scholar]
  20. Pierce J. G., Liao T. H., Carlsen R. B., Reimo T. Comparisons between the alpha chain of bovine thyrotropin and the CI chain of luteinizing hormone. Compositions of tryptic peptides, cyanogen bromide fragments, and carbohydrate moieties. J Biol Chem. 1971 Feb 25;246(4):866–872. [PubMed] [Google Scholar]
  21. Reichert L. E., Jr Biological studies on the relatedness of subunits of human follicle stimulating hormone and chorionic gonadotropin. Endocrinology. 1972 Apr;90(4):1119–1122. doi: 10.1210/endo-90-4-1119. [DOI] [PubMed] [Google Scholar]
  22. Snaith S. M., Levvy G. A. Purification and properties of alpha-D-mannosidase from jack-bean meal. Biochem J. 1968 Dec;110(4):663–670. doi: 10.1042/bj1100663. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Swaminathan N., Bahl O. P. Dissociation and recombination of the subunits of human chorionic gonadotropin. Biochem Biophys Res Commun. 1970 Jul 27;40(2):422–427. doi: 10.1016/0006-291x(70)91026-0. [DOI] [PubMed] [Google Scholar]
  24. Tsuruhara T., Dufau M. L., Hickman J., Catt K. J. Biological properties of hCG after removal of terminal sialic acid and galactose residues. Endocrinology. 1972 Jul;91(1):296–301. doi: 10.1210/endo-91-1-296. [DOI] [PubMed] [Google Scholar]
  25. WARREN L. The thiobarbituric acid assay of sialic acids. J Biol Chem. 1959 Aug;234(8):1971–1975. [PubMed] [Google Scholar]
  26. Ward D. N., Reichert L. E., Jr, Liu W. K., Nahm H. S., Hsia J., Lamkin W. M., Jones N. Chemical studies of luteinizing hormone from human and ovine pituitaries. Recent Prog Horm Res. 1973;29:533–561. doi: 10.1016/b978-0-12-571129-6.50018-x. [DOI] [PubMed] [Google Scholar]

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