Probes for affinity guided conjugation have shown great promise for the preparation of high-quality protein conjugates. However, such probes are often limited in their protein scope. Here, we demonstrate the synthesis and use of imidazole carbamate probes for affinity guided conjugation of an azide handle to a wide variety of metal binding proteins such as antibodies, enzymes, nanobodies and His6-tagged proteins. The azide handles were used to link dyes to the proteins for gel analysis and binding studies. In a comparative study we find that the probe containing three NTA groups show higher selectivity than the probe containing two. In a mixture of proteins, the probe shows preference for labelling His6-tagged proteins.
