Table 3. Relative EIC peak areas of different forms of light chain C-terminal peptide in non-reduced MAb-A and Peak 1 fraction.
| Peptidea | Extracted ion M2H+ |
Relative EIC peak area (%)b |
|
|---|---|---|---|
| MAb-A Lot B | Lot B Peak 1 | ||
| L13-S-S-H12 |
631.25 |
100 |
100 |
| L13-S-S- L13 |
811.33 |
0.1 |
16.5 |
| L13-S-S-GSH |
559.21 |
0.2 |
9.9 |
| L13-S-S-Cys |
466.17 |
0.0 |
4.9 |
| L13-NEM |
469.19 |
0.5 |
1.1 |
| L13 |
406.67 |
0.0 |
0.0 |
| Sum | 100.8 | 132.4 | |
a The samples were treated with NEM and digested with Lys-C. L13, light chain N-terminal peptide with Cys at the N-terminus; -S-S-, disulfide link. bNormalized by dividing the peak area of peptide L13-S-S-H12 in the same sample.