Study of the reaction between nucleic acids and the trihydroxyanthroquinone-Al complex and its analytical application

The reaction between nucleic acids and the trihydroxyanthroquinone (THAQ)-A l complex was studied. The nucleic acids used were fish sperm DNA (fsDNA), calf thymus DNA (ctDNA) and yeast RNA (yRNA). Experiments indicated that th e addition of a very small amount of double-stranded DNA quenched the fluor escence of the THAQ-Al complex. When the mole ratio R of DNA to Al3+ was 0. 53, the fluorescence quenching was a maximum. If R >0.53, the fluorescence increased gradually until a constant value was obtained. If DNA was replace d by RNA or denatured DNA, only a fluorescence quenching effect was observe d. Under optimum conditions, the calibration graphs were linear over the ra nge 3.8 x 10(-8) 1.75 x 10(-6) g ml(-1) fsDNA, 5.0 x 10(-8)-1.5 x 10(-6) g ml(-1) ctDNA and 2.0 x 10(-8)-1.5 x 10(-4) g ml(-1) yRNA. The detection lim its were 6.6 x 10(-9) g ml(-1) fsDNA, 7.3 x 10(-9) g ml(-1) ctDNA and 5.4 x 10(-9) g ml(-1) yRNA. The method was applied to the determination of DNA o r RNA in synthetic samples. The mechanism of the interaction between THAQ-A l and nucleic acids was also discussed. (C) 1999 Elsevier Science B.V. All rights reserved.