FLUORESCENT DYE ASSAY FOR DETECTION OF DNA IN RECOMBINANT PROTEIN PRODUCTS

A homogeneous fluorescence-based DNA detection system has been develop ed to measure DNA in protein solutions. The technique relies on the in crease in fluorescence of a dye molecule when it intercalates into dou ble-stranded (ds) DNA. The increased fluorescence is a direct measurem ent of the amount of DNA in the sample. The analysis time required per sample is less than 5 min. The dye has absorbance and emission maxima at 485 and 530 nm, respectively. The assay is linear from 98 pg/mL to 200 ng/mL of DNA in buffers containing no proteins with typical relat ive standard deviation values of less than 2.4%. The assay performance was evaluated under various matrix conditions, including buffers, pH, ionic salts, detergents, denaturants and organic solvents. Each reage nt was tested at several concentrations to determine how the slope and linearity (r value) of the standard curve were affected. Even in the presence of matrix components and protein, the assay was able to quant itatively detect picogram to nanogram levels of DNA. The fluorescence can be removed by DNase treatment. This method is specific for dsDNA w ith RNA emitting less than 2% intensity of an equivalent mass of DNA.