TNP-ATP (2'-(or-3')-O-(Trinitrophenyl) Adenosine 5'-Triphosphate, Trisodium Salt) (Invitrogen™)

The nucleotide analog TNP-ATP is modified on the ribose moiety and is essentially non-fluorescent in water. The TNP nucleotides undergo an equilibrium transition to a semiquinoid structure that has relatively long-wavelength spectral properties; this form is only fluorescent when bound to the nucleotide-binding site of some proteins.