Figure 3

Typical MaxQuant-annotated spectra instrumental in the identification of new egg white proteins. A, apovitellenin-1 peptide corresponding to sequence positions 75-83. The precursor peptide mass of this doubly charged peptide was determined with a mass error of 0.35 ppm. The peptide posterior error probability (PEP) was 1.1E-15 and the MaxQuant score was 221. This is an example of a short peptide with almost uninterrupted b- and y-ion series. B, vitellogen-1 peptide corresponding to sequence positions 95-108. The precursor mass of this doubly charged peptide was determined with a mass error of 0.18 ppm. The PEP was 1.22E-28 and the MaxQuant score was 234. The most intense y-ion, y3, indicates the well known preferential cleavage N-terminal to proline. C, spectrum of a longer peptide corresponding to sequence positions 666-683 of vitellogenin-2. The precursor mass of this triply charged peptide was determined with a mass error of 0.53 ppm. PEP was 5.2E-42 and the score was 244. The fragmentation pattern shows long uninterrupted b- and y-ion series, but as frequently seen with CID fragmentation of longer peptides, the sequence coverage is not complete.