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The Effect of Posttranslational Modifications on the In VitroActivity of Recombinant Human Thyroid-Stimulating Hormone

Authors :
Sendak, Rebecca A.
Ganesa, Chandrashekar
Lee, Karen L.
Harrahy, John J.
Théberge, Roger
Morgan, Charles J.
Cole, Edward S.
Kohn, Leonard D.
Mattaliano, Robert J.
Source :
Thyroid; December 2003, Vol. 13 Issue: 12 p1091-1101, 11p
Publication Year :
2003

Abstract

Posttranslational modification can influence the biologic activity of recombinant proteins. The effects of β-subunit C-terminal truncation, oligosaccharide heterogeneity, and chemical oxidation on the in vitroactivity of recombinant human thyroid-stimulating hormone (rhTSH) were investigated. β-Subunit C-terminal truncation up to residue 113 did not effect the in vitroactivity of the hormone. The relationship between the heterogeneity of oligosaccharide structures on rhTSH and specific activity of the glycoprotein hormone was also examined. Oligosaccharide profiles were generated for preparations of rhTSH containing similar sialic acid levels. A weak correlation was observed between relative levels of monosialylated biantennary, bisialylated biantennary, and trisialylated triantennary oligosaccharide species and in vitroactivity of the recombinant hormone (p < 0.05).To examine the effect of chemically induced methionine oxidation on the activity of rhTSH, the hormone was treated with tert-butyl hydroperoxide and then characterized. Using peptide mapping and mass spectrometry, the degree of oxidation of the five methionine residues within rhTSH was measured. Met-71 in the α-subunit was the most susceptible to oxidation whereas Met-9 in the β-subunit was the most resistant. Also, after tert-butyl hydroperoxide treatment, levels of oxidation of Met-32 in the β-subunit, and Met-29 and Met-47 in the α-subunit were less than half of that observed for Met-71. The in vitroactivity of rhTSH initially declined with increasing oxidation; however, the loss in activity plateaued at approximately 50% of the control sample activity. In summary, despite the possible effects that posttranslational modifications may have on the bioactivity of a protein, a limited degree of variation in bioactivity was observed for the rhTSH preparations described in this study.

Details

Language :
English
ISSN :
10507256 and 15579077
Volume :
13
Issue :
12
Database :
Supplemental Index
Journal :
Thyroid
Publication Type :
Periodical
Accession number :
ejs5596976
Full Text :
https://doi.org/10.1089/10507250360731488