Table 2.
ESI ion and corresponding ETD product ions for acidic model peptides cationized by Pr(III).
| Peptide sequencea | Number of residues | Number of acidic residuesb | Metallated ion formed by ESI | cn-ions | zn-ions | yn-ions |
|---|---|---|---|---|---|---|
| D1AAAAAA7 | 7 | 2 | [M + Pr]3+ | [/cn + Pr]+, n = 4–6 [/cn + Pr]2+, n = 6 |
zn/+, n = 2 [/zn + Pr]+, n = 5, 6 [/zn + Pr]+, n = 6 |
[yn + Pr]+, n = 4–6 [yn + Pr]2+, n = 6 |
| E1AAAAAA7 | 7 | 2 | [M + Pr]3+ | [/cn + Pr]+, n = 4–6 [/cn + Pr]2+, n = 5, 6 |
[/zn + Pr]+, n = 5, 6 [/zn + Pr]2+, n = 6 |
[yn + Pr]+, n = 4–6 [yn + Pr]2+, n = 6 |
| AAAD4AAA7 | 7 | 2 | [M + Pr]3+ | [/cn + Pr]+, n = 4–6 [/cn + Pr]2+, n = 6 |
zn/+, n = 2 [/zn + Pr]+, n = 4–6 |
– |
| AAAE4AAA7 | 7 | 2 | [M + Pr]3+ | [/cn + Pr]+, n = 4–6 [/cn + Pr]2+, n = 5, 6 |
zn/+, n = 2 [/zn + Pr]+, n = 4–6 [/zn + Pr]2+, n = 6 |
– |
| AAAAAAD7 | 7 | 1 | –c | |||
| AAAAAAE7 | 7 | 1 | [M + Pr – H]2+ | – | [/zn + Pr]+, n = 5–6 | – |
| D1AAD4AAD7 | 7 | 3 | [M + Pr]3+ | cn//+, n = 1–3 [/cn + Pr]+, n = 4–6 [/cn + Pr]2+, n = 6 |
[/zn + Pr]+, n = 5, 6 [/zn + Pr – CO]+, n = 4 |
– |
| E1AAE4AAE7 | 7 | 3 | [M + Pr]3+ | cn//+, n = 1–3 [/cn + Pr]+, n = 4–6 [/cn + Pr]2+, n = 6 |
[/zn + Pr]+, n = 4–6 | – |
| E1E2E3E4E5E6 (E6) | 6 | 6 | [M +Pr – H]2+ | [/cn + Pr]+, n = 4, 5 | [/zn + Pr]+, n = 5 |
– |
| D1D2D3D4D5D6D7 (D7) | 7 | 7 | [M + Pr – H]2+ | cn//+, n = 6 [/cn + Pr]+, n = 5, 6 |
[/zn +Pr]+, n = 6 [/zn + Pr – C2H3O2]+, n = 6 |
– |
| E1E2E3E4E5E6E7 (E7) | 7 | 7 | [M + Pr – H]2+ | [/cn + Pr]+, n = 5, 6 | [/zn + Pr]+, n = 5, 6 | – |
| E1E2E3E4E5E6E7E8 (E8) | 8 | 8 | [M + Pr – H]2+ | [/cn + Pr]+, n = 5–7 | [/zn + Pr]+, n = 5–7 | – |
| D1D2D3D4D5D6D7D8D9D10 (D10) | 10 | 10 | [M + Pr – H]2+ | [/cn + Pr]+, n = 6–9 | [/zn + Pr]+, n = 6–9 | – |
a
Bold font is used to indicate acidic residues. A number immediately following an acidic residue indicates its position in the peptide sequence.
b
Acidic residues refers to the number of aspartic acid (D), glutamic acid (E), and C-terminal residues in the peptide sequence. If an aspartic acid or glutamic acid residue is located on the C-terminus, then it is counted as only one acidic residue.
c
- means that no ETD ions were observed.