CHEMILUMINESCENCE INVESTIGATION OF THE INTERACTION OF METALLOPORPHYRINS WITH NUCLEIC-ACIDS

The interaction of water-soluble cationic porphyrin meso-tetrakis(4-N- methylpyridinyl)porphyrin (TMPyP) manganese derivatives with DNA was d emonstrated by their catalytic activity on the luminol-H2O2 chemilumin escence (CL) system. The catalytic activity of Mn-TMPyP on the CL reac tion was markedly enhanced when the complex was bound to DNA. The nati ve form of DNA and thermally denatured DNA show the same degrees of en hancement. Different degrees of enhancement were obtained when Mn-TMPy P interacted with RNA and polynucleotides, whereas the interaction of nucleotides and bases with Mn-TMPyP had no effect on its catalytic act ivity. To examine the effect of the peripheral group of the porphyrin on its bonding properties, the interaction of manganese tetrakis(4-ami nophenyl)porphyrin (Mn-TPPA(4)), manganese tetrakis(carboxylphenyl)por phyrin (Mn-TPPC4), manganese tetrakis(sulphophenyl)porphyrin (Mn-TPPS4 ) and manganese tetrakis(4-trimethylaminophenyl)porphyrin (Mn-TAPP) wi th DNA was tested. Only the Mn-TPPA(4)-catalysed CL reaction was signi ficantly enhanced. The effects of the native form of DNA and thermally denatured DNA on the Mn-TPPA(4)-catalysed CL reaction were very diffe rent to that on the Mn-TMPyP-catalysed CL reaction. With a fixed conce ntration of Mn-TMPyP there was a saturated concentration of DNA with r espect to the metalloporphyrin (M-P). The binding number of M-P to DNA was estimated. Optimum conditions of the M-P-DNA complex-catalysed lu minol CL reaction were evaluated by using a low-injection system. The use of the analytical parameters of the phenomenon as a means of deter mining DNA was examined. The detection limit (signal-to noise ratio > 3) of DNA was 0.20 ng ml(-1). The relative standard deviation (n = 11) of the determination of 10 ng ml(-1) DNA was 2.6%.