Structural and conformational analysis of glycan moieties in situ on isotopically 13C,15N-enriched recombinant human chorionic gonadotropin

Human chorionic gonadotropin (hCG) maintains its biological activity through glycosylation of the alpha subunit. Glycosylation either makes hCG interact with a lectin-like part of the hCG receptor or reduces the affinity of the hormone for the hCG receptor, preventing its down-regulation. The glycan at Asn 52 plays an important role in the biological activity of hCG by extending into the surrounding solution irrespective of whether it is in the isolated alpha subunit or in complex with beta subunit. Conformations of the glycans do not differ greatly from that of free glycans in solution.