ACMA (9-amino-6-chloro-2-methoxy acridine) forms three complexes in the presence of DNA.

The interaction of ACMA (9-amino-6-chloro-2-methoxy acridine) (D) with DNA (P) has been studied by absorbance, fluorescence, circular dichroism, spectrophotometry, viscometry and unwinding electrophoresis. A T-jump kinetic study has also been undertaken. The experimental data show that, totally unlike other drugs, ACMA is able to form with DNA three complexes (PD(I), PD(II), PD(III)) that differ from each other by the characteristics and extent of the binding process.

DNA binding of a proflavine derivative bearing a platinum hanging residue.

New platinum(II) complex of 3,6-diamine-9-[6,6-bis(2-aminohethyl)-1,6-diaminohexyl]acridine, AzaPt, has been synthesised and characterised. Behaviour of AzaPt in solution (protonation and possible self-aggregation phenomena) has been investigated by spectral methods (absorbance and fluorescence) at I=0.1M and 25°C, and the equilibrium parameters of binding to calf thymus DNA have been established.

DNA interaction with Ru(II) and Ru(II)/Cu(II) complexes containing azamacrocycle and dppz residues. A thermodynamic, kinetic and theoretical study.

Ru(ii) complexes that bring together the properties of the dppz (dipyrido[3,2-a:2',3'-c]phenazine) intercalating residue and the properties of metal-coordinating macrocycles (L = 4,4'-(2,5,8,11,14-pentaaza[15])-2,2'-bipyridilophane) have been synthesised and their protonation and affinity for copper(ii) was analysed. Ru(bpy)(dppz)L(2+) (D2(2+)) and Ru(dppz)(2)L(2+) (D3(2+)) were found to interact with DNA but the binding mode is not simple and its features strongly depend both on the ligand structure and on the [DNA]/[complex] ratio. Equilibrium measurements (spectrophotometric and spectrofluorometric titrations), kinetics (stopped-flow technique) and theoretical calculations all concur in suggesting that for the less hindered D2(2+) an important contribution of external binding, driven by dye-dye interactions, is operative, as revealed by the onset of positive cooperativity.

New aspects of the interaction of the antibiotic coralyne with RNA: coralyne induces triple helix formation in poly(rA)*poly(rU).

The interaction of coralyne with poly(A)*poly(U), poly(A)*2poly(U), poly(A) and poly(A)*poly(A) is analysed using spectrophotometric, spectrofluorometric, circular dichroism (CD), viscometric, stopped-flow and temperature-jump techniques. It is shown for the first time that coralyne induces disproportionation of poly(A)*poly(U) to triplex poly(A)*2poly(U) and single-stranded poly(A) under suitable values of the [dye]/[polymer] ratio (C(D)/C(P)). Kinetic, CD and spectrofluorometric experiments reveal that this process requires that coralyne (D) binds to duplex.

Solvent effects on the thermodynamics and kinetics of coralyne self-aggregation.

The role of solvent effects on the thermodynamics and kinetics of the coralyne self-aggregation process has been investigated in ethanol-water mixtures of different compositions. The changes in the UV/visible spectra of coralyne and FAB/LSIMS mass spectrometry agreed well with the formation of a dimer species. 1D and 2D 1H experiments have allowed one to look into the features of the self-aggregation process and to determine the equilibrium constant and the deltaH0 and deltaS0 values for the aggregate formation in 0-50% ethanol-water mixtures.

DNA binding by a new metallointercalator that contains a proflavine group bearing a hanging chelating unit.

The new bifunctional molecule 3,6-diamine-9-[6,6-bis(2-aminoethyl)-1,6-diaminohexyl]acridine (D), which is characterised by both an aromatic moiety and a separate metal-complexing polyamine centre, has been synthesised. The characteristics of D and its ZnII complex ([ZnD]) (protonation and metal-complexing constants, optical properties and self-aggregation phenomena) have been analysed by means of NMR spectroscopy, potentiometric, spectrophotometric and spectrofluorimetric techniques. The equilibria and kinetics of the binding process of D and [ZnD] to calf thymus DNA have been investigated at I=0.

Influence of cyanine dye structure on self-aggregation and interaction with nucleic acids: a kinetic approach to TO and BO binding.

Kinetics and equilibria of cyanine dyes thiazole orange (TO) and benzothiazole orange (BO) self-aggregation and binding to CT-DNA are investigated in aqueous solution at 25 degrees C and pH 7. Absorbance spectra and T-jump experiments reveal that BO forms J-aggregates while TO forms more stable H-aggregates. Fluorescence and absorbance titrations show that TO binds to DNA more tightly than BO.

A macrocyclic ligand able to bind gallium(III) by preorganized pendant arms; coordination and kinetic studies.

The equilibria and kinetics of the binding of gallium(III) to 4-(N),10-(N)-bis[2-(3-hydroxo-2-oxo-2-H-pyridine-1-y1)acetamido]-1,7-dimethyl-1,4,7,10-tetraazacyclododecane (L) were investigated in acidic medium at ionic strength 1 M (NaClO4). Spectrophotometric titrations in the UV region revealed that L is able to bind Ga3+ also at high H+ concentration. The kinetic (stopped-flow) experiments are interpreted on the basis of three parallel reaction paths (i) M3+ + H2L2+ = M(H2L)5+ where M(H2L)5+ is in a steady state, (ii) M(OH)2+ + H2L2+ = M(HL)4+ + H2O and (iii) M(OH)2+ + HL+ = ML3+ + H2O.