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Fig. 5 | Heritage Science

Fig. 5

From: Mixing, dipping, and fixing: the experimental drawing techniques of Thomas Gainsborough

Fig. 5

a MS/MS spectrum of peptides identified in a reference sample of modern milk. The data shows a triply charged ion at m/z 910.0919 (error Δm 0.9 ppm), enabling identification of the 118–134 peptide of alpha S1 casein, which includes two lactosylations (lower case K118 and K120) and one phosphorylation (S130). b, c MS/MS spectra of peptides identified in sample S2C2 from Coastal Scene with Shipping, Figures, and Cows (ca. 1780; 2017.89). The data shows (B) a triply charged ion at m/z 694.0209 (error Δm 0.5 ppm), enabling identification of the 118-134 peptide of alpha S1 casein, which includes one phosphorylation (S130); and (C) a doubly charged ion at m/z 831.3934 (error Δm 0.8 ppm), enabling identification of the 121-134 peptide of alpha S1 casein, which includes one phosphorylation (S130) and one deamidation (Q123)

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