Determination of Nucleic Acids at Nanogram Levelsby their Enhancement Effect on the Rateof the Metalloporphyrin-Catalyzed p-HydroxyphenylaceticAcid Fluorescence Reaction

Abstract.

 Nucleic acids were determined on the basis of the finding that the catalytic activity of iron(III) tetrakis(o-aminophenyl)porphyrin (Fe(III)(o-NH₂)TPP), a mimetic peroxidase, in the fluorogenic reaction between p-hydroxyphenylacetic acid (p-HPA) and H₂O₂ is significantly enhanced in the presence of DNA (or RNA). The degree of fluorescence enhancement is a measure of the nucleic acid concentration. Under optimum conditions, the calibration curves for the determination of calf thymus (CT DNA) and yeast RNA were linear over the ranges 0–200.0 ng mL⁻¹. The corresponding detection limits are 0.8 ng mL⁻¹ for CT DNA and 1.1 ng mL⁻¹ for yeast RNA, respectively. The relative standard deviation of seven replicate measurements is 2.2% for 100 ng mL⁻¹ CT DNA. Interferences from some interesting co-existing substances in the determination of DNA were also examined. The potential application of the method was also further proved by the determination of DNA in golden staphylococcus DNA sample.