Table 4.
Peptide Charge State Distributions for Peptides with Various Positive Side Chain Counts*
| Peptide 0 | Peptide 1 | Peptide 2 | Peptide 3 | ||
|---|---|---|---|---|---|
| 0.2 % FA only | +1 | 68 | 08 | 07 | 01 |
| +2 | 32 | 92 | 51 | 21 | |
| +3 | n.d. | 00 | 42 | 39 | |
| +4 | n.d. | n.d. | n.d. | 39 | |
| Summed intensity | 1.0e6 | 8.4e6 | 5.6e6 | 2.0e7 | |
| + 5.0 % DMSO | +1 | 97 | 02 | 00 | 00 |
| +2 | 03 | 98 | 90 | 14 | |
| +3 | n.d. | 00 | 10 | 70 | |
| +4 | n.d. | n.d. | n.d. | 16 | |
| Summed intensity | 1.6e6 | 1.7e7 | 1.5e7 | 4.2e7 | |
| + 0.1 %m-NBA | +1 | 04 | 00 | 00 | 00 |
| +2 | 96 | 60 | 21 | 00 | |
| +3 | n.d. | 40 | 78 | 25 | |
| +4 | n.d. | n.d.* | n.d. | 75 | |
| Summed intensity | 2.0e6 | 1.7e7 | 1.4e7 | 4.4e7 | |
n.d. = not detected.
*
Normalized ratio of integrated peak area from the EIC of each charge state of each peptide, numbered in order of potential positive charge sites. Each value is the average of two replicate injections. Peptide 0: peptic peptide containing no positive charge-bearing side-chains, SDIPNPIGSENS. Peptide 1: tryptic peptide containing only one positive residue, YNGVFQECCQAEDK. Peptide 2: elastase generated peptide containing two positive residues, TEDELQDKIHPF. Peptide 3. Tryptic peptide containing one lysine and two histidines positive side chains, TYFPHFDSHGSAQVK