Identifying transglutaminase substrate glutaminyls using dansylcadaverine

Dansylcadaverine is often used at a final concentration of 1 mM to identify transglutaminase substrate glutaminyl residues. At this concentration, dansylcadaverine only labels a fraction of the possible substrates. Therefore, we developed a 500 mM stock dansylcadaverine solution in dimethyl sulfoxide:acetic acid (19:1) that allows the identification of all transglutaminase substrate glutaminyl residues. This solution was used to identify these substrate residues: Gln 283, Gln 325, and Gln 677 in a fragment of arginine-specific gingipain A.