ABNOH‐Linked Nucleotides and DNA for Bioconjugation and Cross‐linking with Tryptophan‐Containing Peptides and Proteins

Reactive N ‐hydroxy‐9‐azabicyclo[3.3.1]nonane (ABNOH) linked 2′‐deoxyuridine 5′‐ O ‐mono‐ and triphosphates were synthesized through a CuAAC reaction of ABNOH‐PEG 4 ‐N 3 with 5‐ethynyl‐dUMP or ‐dUTP. The modified triphosphate was used as substrate for enzymatic synthesis of modified DNA probes with KOD XL DNA polymerase. The keto‐ABNO radical reacted with tryptophan (Trp) and Trp‐containing peptides to form a stable tricyclic fused hexahydropyrrolo‐indole conjugates. Similarly modified ABNOH‐linked nucleotides reacted with Trp‐containing peptides to form a stable conjugate in the presence but surprisingly even in the absence of NaNO 2 (presumably through activation by O 2 ). The reactive ABNOH‐modified DNA probe was used for bioconjugations and crosslinking with Trp‐containing peptides or proteins.