Kinetic investigation of the DNA platination reaction: evidence for a transient adduct between deoxyribonucleic acid and cis-platinum(II)

Abstract

Kinetics of the synthesis of adducts between salmon testis DNA and platinum(II) compounds were measured by their effects on DNA synthesis, circular dichroism, and ethidium bromide dependent fluorescence. Transient incorporation of [14C]cyanide into DNA adducts of of cis-diammineaquochloroplatinum(II) and respectively cis-diamminediaquoplatinum(II) compounds but not of trans-diammineaquochlorplatinum(II) was observed. A minimal kinetic scheme is derived, in which a transient monodentate DNA-platinum(II) adduct is formed in a bimolecular reaction between DNA and aquated platinum(II) compounds. Second-order rate constants are 2000-3000 M-1 min-1 for cis-diamminediaquoplatinum(II) and 280-400 M-1 min-1 for cis- and trans-diammineaquochloroplatinum(II), respectively. The dependence of pseudo-first-order rate constants is not linear for high concentrations of DNA, suggesting competitive formation of more than one primary adduct. The monodentate adducts inhibit DNA polymerase catalyzed DNA synthesis. The biomolecular reaction is followed by a rearrangement (rate constant 0.22 min-1) that gives rise to most of the decrease in the fluorescence intensity and that depends on the state of aquation of the DNA-bound platinum(II) complex. By exchange of coordinated water with a second nucleotide, the monodentate adduct can form cross-links in a reaction joining the rearrangement. Adducts containing a chloro group liberate it by hydrolysis prior to cross-linking. In the case of the trans-platinum(II) adduct, the hydrolysis is aided by the trans effect of the bound first nucleotide.(ABSTRACT TRUNCATED AT 250 WORDS)

Interaction of Platinum Antitumor Compounds with DNA

“…2.5 hr Bancroft et al (1990) stants and activation parameters for mono adduct closure with those for hydrolysis of related platinum complexes indicates that, as reported previously (Malinge and Leng 1988;Schaller et al 1987), hydrolysis of chloride is ratedetermining for monoadduct closure. Since the lifetimes are similar for both isomers, the different biological activities cannot be attributed to large differences in rates of monoadduct closure.…”

“…Various spectroscopic studies reveal that both cis-and trans-DDP perturb base stacking in duplex DNA, but only upon closure of the monofunctional to bifunctional adducts Butour 1978a, 1978b;Schaller et al 1987). Binding of [Pte dien))2+ to random sequence DNA does not disrupt base stacking as measured by circular dichroism, but actually stabilizes the double helix, raising the UV melting temperature by 1° to 2°C Butour 1978a, 1978b;Vrana et al 1986).…”

Differential Effects of Chromium(VI) on Constitutive and Inducible Gene Expression in Chick Embryo Liver In Vivo and Correlation With Chromium(VI)‐Induced DNA Damage

“…Since the alkaline elution technique detects only DNA interstrand cross-links, DNA-protein crosslinks, and DNA strand breaks, it is likely that chromium(V1) -induced DNA lesions that are undetectable by alkaline elution, such as monoadducts or DNA intrastrand crosslinks, are responsible for the observed effects of chromium(Vl) on gene expression at early times. Formation of DNA interstrand and intrastrand cross-links by the inorganic antitumor agent (and carcinogen) cisplatin, has been found to occur in a sequence of two steps, i.e., initial formation of R-DNA monoadducts followed by partial conversion of the monoadducts to cross-links [35,36]. The formation of monodentate and cross-linked Pt-DNA adducts has been shown to result in inhibition of DNA template primer activity when assayed for DNA synthesis by Escherichia coli DNA polymerase I [36,371, or RNA synthesis by E. coli RNA polymerase [38] in vitro.…”

A Complete Kinetic Study of GG versus AG Platination Suggests That the Doubly Aquated Derivatives of Cisplatin Are the Actual DNA Binding Species

“…Reactions of 2 in acidic conditions are complicated by the hydrolysis of 2 to 3 (Scheme 2) and this occurs in parallel with the direct reaction of 2 with the oligonucleotide. Since 3 is considerably more reactive towards nucleobases than 2, [22,23] the commonly used approximation neglecting the reaction between 3 and the oligonucleotide [12,13,16,24] yields unprecise results. Our solution to the problem resided in separate investigations of the reaction of 3 in a series of experiments that we reported earlier [18] (indicated by bold arrows in Schemes 2 and 3) and allowed the reactions of 2 (Scheme 2) and 4 (Scheme 3) to be studied with a reduced number of variables.…”