Table I. Target Staphylococcal bacteriophage 53 capsid protein peptide sequences and their corresponding 15N metabolically labeled counterparts. The unique peptide sequences were chosen to identify the 35 kDa (14N) and 35.5 kDa (15N) capsid protein from Staphylococcal bacteriophage 53. MS/MS = mass spectrometry/mass spectrometry.
| Target peptide | Actual Mass Da | Precursor Ion m/z | Fragment Ion (quantitation) | Fragment Ion (confirmation) | Fragment Ion (confirmation) |
|---|---|---|---|---|---|
| SIAQSIEK-14N | 874.5 | 438.2 (+2) | 675.4 (y6) | 476.3 (y4) | 604.3 (y5) |
| SIAQSIEK-15N | 884.5 | 443.2 (+2) | 683.4 (y6) | 481.3 (y4) | 611.3 (y5) |
| LGVILPVTK-14N | 938.6 | 470.3 (+2) | 670.5 (y6) | 557.4 (y5) | 444.3 (y4) |
| LGVILPVTK-15N | 948.8 | 475.4 (+2) | 677.4 (y6) | 563.3 (y5) | 449.3 (y4) |
| LIYGIPQLIEYK-14N | 1448.8 | 725.4 (+2) | 890.5 (y7) | 1223.7 (y10) | 1060.6 (y9) |
| LIYGIPQLIEYK-15N | 1462.8 | 732.4 (+2) | 899.5 (y7) | 1235.7 (y10) | 1071.6 (y9) |