The nucleotide analog MANT GMPPNP is modified on the ribose moiety. The compact mature of the MANT fluorophore and its attachment position results in nucleotide analogs that induce minimal perturbation of nucleotide-protein interactions. Because MANT fluorescence is sensitive to the environment of the fluorophore, nucleotide-protein interactions may be directly detectable. MANT nucleotides are valuable probes of the structure and enzymatic activity of nucleotide-binding proteins.