Squaramate-linked 2 '-deoxycytidine 5 '-O-triphosphate was synthesized and found to be good substrate for KOD XL DNA polymerase in primer extension or PCR synthesis of modified DNA. The resulting squaramate-linked DNA reacts with primary amines to form a stable diamide linkage.
This reaction was used for bioconjugations of DNA with Cy5 and Lys-containing peptides. Squaramate-linked DNA formed covalent cross-links with histone proteins.
This reactive nucleotide has potential for other bioconjugations of nucleic acids with amines, peptides or proteins without need of any external reagent.