Table 2. Multiple sites of attachment of peptide amides reacted with iTRAQ reagent.
| Peptide | Theoretical [M+H]+ | Observed [M+H]+ | Observed iTRAQ tagsα | % Relative Intensity |
|---|---|---|---|---|
| 619-YASEGLSK (853)b | 1141.6 | 1141.5 | 2 | 100.0 |
| 1285.7 | 1285.6 | 3 | 42.9 | |
| 620-YPSEGLSK (879) | 1167.6 | 1167.7 | 2 | 94.9 |
| 1311.7 | 1311.8 | 3 | 100.0 | |
| 1455.8 | 1455.9 | 4 | 16.2 | |
| 621-YWSEGLSK (968) | 1256.6 | 1256.5 | 2 | 100.0 |
| 622-YYSEGLSK (946) | 1233.6 | 1233.7 | 2 | 100.0 |
| 1377.7 | 1377.8 | 3 | 80.7 | |
| 1521.8 | 1521.9 | 4 | 3.0 | |
| 623-YESEYLSK (1017) | 1161.5 | 1161.5 | 1 | 4.8 |
| 1305.6 | 1305.6 | 2 | 28.1 | |
| 1449.7 | 1449.7 | 3 | 100.0 | |
| 1593.8 | 1593.8 | 4 | 2.9 | |
| 623 after hydroxylamine | 1161.5 | 1161.5 | 1 | 2.6 |
| 1305.6 | 1305.6 | 2 | 100.0 | |
| 679-ASEHASYG (820) | 964.4 | 964.4 | 1 | 1.8 |
| 1108.5 | 1108.5 | 2 | 35.8 | |
| 1252.6 | 1252.6 | 3 | 100.0 | |
| 1396.7 | 1396.7 | 4 | 0.89 | |
| 680-ASEHAYYG (896) | 1040.4 | 1040.4 | 1 | 3.4 |
| 1184.5 | 1184.5 | 2 | 35.6 | |
| 1328.6 | 1328.6 | 3 | 100.0 | |
| 1472.7 | 1472.7 | 4 | 40.2 | |
| 681-ASEHATYG (834) | 1122.5 | 1122.5 | 2 | 17.1 |
| 1266.6 | 1266.6 | 3 | 100.0 | |
| 1410.7 | 1410.8 | 4 | 0.47 | |
| 681 after hydroxylamine | 978.4 | 978.5 | 1 | 100.0 |
| 1122.5 | 1122.5 | 2 | 2.1 |
a
Determined using MALDI TOF/TOF.
b
Number before peptide sequence is an in-house reference number referred to in the text; number in parenthesis is [M+H]+ of unmodified peptide amide.