US Patent 8652781 Cognate sampling kinetics

Provided are methods and compositions for measuring the transient binding of nucleotides and nucleotide analogs under conditions where the nucleotides or nucleotide analogs are unincorporable. The transient binding can be determined under single molecule observation conditions providing information about the kinetics of nucleotide analog sampling of the active site of the enzyme. The methods can be used for polymerase enzyme development, mechanistic understanding, and drug discovery.