Table 1.
Quantification of Trastuzumab–TCO Derivatives Using UV–vis (absorption at 280 and 500 nm) and MALDI Analysisc
| molecule | mass (m/z) | mass differencea (m/z) | labeling ratio BODIPY/Ab | A280 (1 cm) | A500 (1 cm) | [BODIPY]b M | [trastuzumab] M (corrected) | labeling ratio BODIPY/Ab |
|---|---|---|---|---|---|---|---|---|
| Trastuzumab | 147 366 | - | - | - | - | - | - | - |
| Conjugate A | 148 806 | 1440 | 1.00 | 0.91 | 0.29 | 3.7 × 10–6 | 3.85 × 10–6 | 0.95 |
| Conjugate B | 150 793 | 3427 | 2.40 | 0.99 | 0.8 | 1.0 × 10–5 | 3.87 × 10–6 | 2.62 |
a
Calculated by subtracting the MALDI mass of trastuzumab from the MALDI mass of a respective conjugate and dividing the resultant mass by the mass of the PEG4-TCO-dihydropyridazine-BODIPY-DFO clicked product (~1428.8 Da).
b
Calculated based on an extinction coefficient of 79 000 M−1 cm−1 at 500 nm (unpublished data)
c
Trastuzumab was utilized as a mass reference for the measurements.