Abstract: A method of assaying compounds for their ability to effect enzymes including enhancing or inhibiting the effect of those enzymes on double stranded DNA sequences is disclosed. The method comprises providing a modified nucleotide sequence comprised of a base analogue which analogue is characterized by increased fluorescence when moved out of its normal helical position, the sequence having a complimentary sequence hybridized thereto to provide a double stranded sequence. The modified sequence containing the base analogue is brought into contact with the enzyme which enzyme is characterized by effecting the 3-dimensional position of the analogue within the sequence. The enzyme is brought into contact with the sequences in the presence of a compound being assayed. By knowing the amount of increased fluorescence the enzyme would normally have on the sequence is possible to determine the inhibitory or enhancing effect of the compound on the enzyme.