Page 46 - Tyrosine-Based Bioconjugations - Jorick Bruins

Chapter 2
product after incubation at 37 °C for 30 min with an apparent high conversion (Figure 2A). Negative controls indicated the specificity of conjugation: no fluorescently labelled LamA was detected in the absence of mTyr (lane C). Incubation with mTyr without 1 led solely to an unidentified band (lane B), most likely originating from aspecific intramolecular nucleophilic attack of an amino acid residue (e.g. Lys and His) to the generated quinone, causing it to appear at the expected position.22, 23 A No fluorescence was detected when SPOCQ was performed with wt-LamA (lane I), which implies that only the newly introduced C-terminal tyrosine is oxidized and undergoes SPOCQ.
Figure 2. (A) SDS-PAGE analysis of SPOCQ on LamA–G4Y and wt-LamA. (B) MS profile of LamA-G4Y, C) MS profile of LamA-G4Y after SPOCQ with 1.
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