Identification of post-translational modifications resulting from LH beta polymorphisms by matrix-assisted laser desorption time-of-flight mass spectrometric analysis of pituitary LH beta core fragment
Article
Jacoby, E., Kicman, A. and Iles, R. 2003. Identification of post-translational modifications resulting from LH beta polymorphisms by matrix-assisted laser desorption time-of-flight mass spectrometric analysis of pituitary LH beta core fragment. Journal of molecular endocrinology. 30 (2), pp. 239-252. https://doi.org/10.1677/jme.0.0300239
Type | Article |
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Title | Identification of post-translational modifications resulting from LH beta polymorphisms by matrix-assisted laser desorption time-of-flight mass spectrometric analysis of pituitary LH beta core fragment |
Authors | Jacoby, E., Kicman, A. and Iles, R. |
Abstract | Metabolism of the human chorionic gonadotrophin (hCG)- and LHbeta-subunits (hCGbeta, LHbeta) terminates with the urinary excretion of core fragment (hCGbetacf, LHbetacf) molecules that retain antigenic shape and constituent N-linked carbohydrate moieties. We have previously demonstrated the resolved mass spectra of hCGbetacf, from which the carbohydrate moieties present at two N-linked glycosylation sites were identified. LHbetacf was subjected to the same mass spectrometric analysis. As LHbeta shares 82% homology with hCGbeta but possesses only one glycosylation consensus site a simpler spectral fingerprint of LHbetacf glycoforms was expected. LHbetacf was reduced with dithiothreitol and analysed by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. Glycoforms were predicted by subtracting the peptide mass from the m/z values of the observed peaks and then sequentially subtracting the masses of the monosaccharide residues of hCGbeta N-linked carbohydrates reported in the literature. The mass spectra of LHbetacf revealed a broad single peak ranging from m/z 8700 to 10 700. Following reduction, this peak was replaced by a set of partially resolved peaks between m/z 4130 and 5205 corresponding to glycosylated forms of the peptide LHbeta6-40. A peak at m/z 4252.2 corresponded to the non-glycosylated peptide LHbeta55-93. Remaining peaks indicated that the pooled sample comprised a wide set of glycoforms, contained LHbetacf with two N-linked carbohydrate moieties and indicated evidence of further glycosylation due to amino acid substitution in polymorphic variants. This is evidence that a single nucleotide polymorphism alters the post-translational modification of a protein and hence its structural phenotype. |
Publisher | Society for Endocrinology |
Journal | Journal of molecular endocrinology |
ISSN | 0952-5041 |
Publication dates | |
2003 | |
Publication process dates | |
Deposited | 20 May 2009 |
Output status | Published |
Digital Object Identifier (DOI) | https://doi.org/10.1677/jme.0.0300239 |
Language | English |
https://repository.mdx.ac.uk/item/81q31
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