Table 2.
Trastuzumab PTMs and observed interfering isoforms. Trastuzumab modifications are organized by specific interfering isoforms which we observed using our CVMS method and the theoretical delta mass shown in ppm and nominal delta mass in Da. The maximum tolerance allowable for deconvolution mass and Sliding Window merge is calculated as ∆M/2, where ∆M relates to the difference in mass between two near-isobaric isoforms and a random dispersion of data points is assumed.
| Modification | Mass/Merge Tolerance | ||
|---|---|---|---|
| Example of Interfering Isoforms | ∆M (ppm, Da) | Required for Deconvolution and Sliding Window Methods (ppm) |
|
| Deamidation | G0F/G0F vs. | 6.75, 1 | ±3.3 |
| G0F/G0F + Deamidation | |||
| Succinimide | G0F/G0F vs. | 118, 18 | ±69 |
| (from Aspartic Acid) | G0F/G0 + Succinimide (D) | ||
| Lysine | G0F/G1F vs. G0F/G0F + Lysine | 224, 34 | ±112 |
| Sialic Acid | G2F/G2F vs. G0F/S1G1F | 224, 34 | ±112 |
| Hexose | G0F/G0F vs. G0F/G1F | 1069, 162 | ±534.5 |