Negative ion mode matrix-assisted laser desorption/ionisation time-of-flight mass spectrometric analysis of oligosaccharides using halide adducts and 9-aminoacridine matrix

2008 ◽  
Vol 22 (8) ◽  
pp. 1153-1158 ◽  
Author(s):  
Jana Becher ◽  
Alexander Muck ◽  
Axel Mithöfer ◽  
Aleš Svatoš ◽  
Wilhelm Boland
Keyword(s):  
Time Of Flight ◽  
Laser Desorption ◽  
Mass Spectrometric ◽  
Mass Spectrometric Analysis ◽  
Negative Ion ◽  
Spectrometric Analysis ◽  
Negative Ion Mode ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

scholarly journals Identification of post-translational modifications resulting from LHbeta polymorphisms by matrix-assisted laser desorption time-of-flight mass spectrometric analysis of pituitary LHbeta core fragment

2003 ◽  
Vol 30 (2) ◽  
pp. 239-252 ◽  
Author(s):  
ES Jacoby ◽  
AT Kicman ◽  
RK Iles
Keyword(s):  
Mass Spectra ◽  
Time Of Flight ◽  
Laser Desorption ◽  
Mass Spectrometric ◽  
Mass Spectrometric Analysis ◽  
Spectrometric Analysis ◽  
Core Fragment ◽  
Peptide Mass ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

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.

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