N- and O-linked Protein Glycosylation

Glycopeptide Heterogeneity and Mass Pattern Recognition

Sugar	Composition	+1	+2	+3	+4	+5
dHexose	C₆O₄H₁₀	146.1	73	48.7	36.5	29.2
Hexose	C₆O₅H₁₀	162.1	81.0	54.0	40.4	32.4
HexNAc	C₈O₅NH₁₃	203.2	101.6	67.7	50.8	40.6
NANA	C₁₁O₈NH₁₇	291.3	145.6	97.1	72.8	58.2
HexNac+Hex	C₁₄O₁₀NH₂₃	365.3	182.6	121.8	91.3	73.1

Example ESI Mass Spectrum

Above is a sample electrospray mass spectrum showing peaks that differ by 54 amu this is typical of a glycopeptide displaying mannose type glycosylation heterogeneity at the [M+3H]³⁺ charge state (see the chart above). To confirm the observation look for peaks that differ by 40.4 amu in the lower end of the spectrum indicating a quadruply charged series.

Monosaccharide table with structures

Simple monosaccharide mass table

Low mass CID marker ions

References

IUPAC-IUB Joint Commission on Biochemical Nomenclature (JCBN), Nomenclature of glycoproteins, glycopeptides and peptidoglycans glycopeptides and peptidoglycans glycopeptides and peptidoglycans, Recommendations 1985.

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