Tris(hydroxymethyl)aminomethane Compatibility with N‑Hydroxysuccinimide Ester Chemistry: Biotinylation of Peptides and Proteins in TRIS Buffer

N-Hydroxysuccinimide esters of small molecules are widely used to modify biomolecules such as antibodies or proteins. Primary amine groups preferably react with the ester to form covalent amide bonds. Currently, protocols strongly recommend replacing the buffer reagent tris­(hydroxymethyl)­aminomethane, and it has even been proposed as a stop reagent. Here, we show that TRIS indeed does not interfere with biotinylation of biomolecules with NHS chemistry.