Characterization of beta subunit variants of recombinant human chorionic gonadotrophin

Human chorionic gonadotropin (hCG), an endogenous glycoprotein hormone, has been widely used for the treatment of infertility and corpus luteum defect in women. The biological specificity of hCG is essentially determined by its beta (0-) subunit, whereas the alpha (a-) subunit is a common subunit shared among the gonadotropin family. In development of a therapeutic recombinant hCG, the purity analysis showed that the beta (0-) subunit has two variants, 01 and 02. Structural characterization using a combination of analytical techniques has demonstrated that 01-subunit is derived from non-glycosylation at Asn 13, whereas 02-subunit is a normal species with complete N-glycosylation at both Asn 13 and Asn 30. In vivo Bioactivity evaluation of the r-hCG fractions with various ratios of 01-and 02-subunits showed that incomplete glycosylation at Asn 13 potentially reduced the biological activity of r-hCG to promote uterus growth. Although hCG has a long history of medicinal use, this is the first report to identify the structural difference of hCG 0 -subunit variants, as well as to preliminary establish the structure-activity relationship of this variation. The obtained results also suggest the importance of variant characterization and necessary quality control of product variants during the development of recombi-nant protein therapeutics.

Automated summary

Human chorionic gonadotropin (hCG), a glycoprotein hormone, is used for infertility treatment. The beta (0-) subunit determines its specificity, while the alpha (a-) subunit is shared by gonadotropin family. Analysis showed that the beta (0-) subunit has two variants, 01 and 02, with different glycosylation patterns at Asn 13 and Asn 30.