Fig. 3.

Representative data-dependent MS/MS spectra of yeast and grape O-glycopeptides in sparkling wine. Each panel contains a schematic of the fragmentation pattern of the glycopeptides; not all ions have been labeled in the spectra for ease of interpretation. Each panel also includes a representative extracted ion chromatogram of the MS2 fragment ions used for quantification by DIA. A, VITGVPWYSSR from Pau5 (UniProt ID P43575) with six hexoses attached at m/z 746.3205 (3+) with a −17.15 ppm precursor mass error. B, peptide VNLVELGVYVSDIR from seripauperins 1 to 24 with two hexoses attached at m/z 950.4798 (3+) with a −14.42 ppm precursor mass error. Spectra for the O-linked peptides from A and B were from the analysis of sparkling cuvée aged 8 months. C, peptide VVRPppTpKPpT from a putative proline-rich cell wall protein (National Center for Biotechnology Information reference NP_001268136.1) found in Sauvignon blanc fermented with the yeast DV10 aged 16 months. The glycopeptide with six pentoses attached was observed at m/z 714.6610 (3+) with a −12.74 ppm precursor mass error. Lowercase prolines represent likely sites of hydroxyproline.