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. 2017 Feb 16;12(2):e0171990. doi: 10.1371/journal.pone.0171990

Fig 1. MS/MS spectrum of the precursor at m/z 1548.6924.

Fig 1

The peptide was identified as SFNEGTDKFTGYGK from the Cannabis sativa polygalacturonase non-catalytic protein (NCBI EST database GI:156080210). The upper panel shows the MS/MS spectrum with y- and b-ions indicated respectively in red and green. The one-letter code is used for the amino acids and dF indicates a didehydrophenylalanine. The lower spectra illustrate the specificity of the modification. While no mass shift is observed for the Phe closest to the N-terminus, illustrated by the lack of secondary peak at 233 for the b2-ion shown in the left panel, the more C-terminal Phe is completely modified as illustrated for the y6- and b9-fragment in the central and right lower panel.