piperidines and chloroacetaldehyde

The effects on the conformation of DNA produced by the monofunctional adducts of chloro-(diethylenetriamine)platinum(II) chloride or cis-diamminemonoaquamonochloroplatinum(II) have been investigated by means of the single-strand-specific probe chloroacetaldehyde (CAA). The denatured sites to which CAA was bound and that were induced in DNA by the monofunctional adducts of the platinum complexes were characterized by means of three experimental approaches. These include measurement of the fluorescence of a plasmid fragment treated with CAA, analysis of oligonucleotides treated with CAA and cleaved by piperidine, and termination of duplex transcription on a fragment of plasmid DNA treated with CAA. The results indicate that the denaturational change preferentially occurs in the base pair containing the monoadducted deoxyriboguanosine in the trinucleotide sequence Py-deoxyriboguanosine-Py (Py is a pyrimidine deoxyribonucleoside). It was suggested that this conformational alteration facilitates in DNA the formation of minor bifunctional adducts of cis-diamminedichloroplatinum(II).

Topics: Acetaldehyde; Base Composition; Base Sequence; Chromosome Mapping; Cisplatin; Deoxyribonucleases, Type II Site-Specific; DNA; Enzyme-Linked Immunosorbent Assay; Hydrogen Bonding; Molecular Sequence Data; Nucleic Acid Conformation; Nucleic Acid Denaturation; Piperidines; Spectrometry, Fluorescence; Transcription, Genetic

The purpose of this work was to analyze at the nucleotide level the distortions induced by the binding of cis-diamminedichloroplatinum(II) (cis-DDP) to DNA by means of chemical probes. In order to test the chemical probes, experiments were first carried out on two platinated oligonucleotides. It has been verified by circular dichroism and gel electrophoresis that the binding of cis-DDP to an AG or to a GTG site within a double-stranded oligonucleotide distorts the double helix. The anomalously slow electrophoretic mobility of the multimers of the platinated and ligated oligomers strongly suggests that the platinated oligonucleotides are bent. The reactivity of the oligonucleotide platinated at the GTG site with chloroacetaldehyde, diethyl pyrocarbonate, and osmium tetraoxide, respectively, suggests a local denaturation of the double helix. The 5'G residue and the T residue within the adduct are no longer paired, while the 3'G residue is paired. The double helix is more distorted (but not denatured) at the 5' side of the adduct than at the 3' side. In the case of the oligonucleotide platinated at the AG site, the double helix is also more distorted at the 5' side of the adduct than at the 3' side. The G residue within the adduct is paired. The reactivities of the chemical probes with six platinated DNA restriction fragments show that even at a relatively high level of platination only a few base pairs are unpaired but the double helix is largely distorted. No local denaturation has been detected at the GG sites separated from the nearest GG or AG sites by at least three bases pairs.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Acetaldehyde; Base Sequence; Circular Dichroism; Cisplatin; Diethyl Pyrocarbonate; DNA; Kinetics; Molecular Sequence Data; Nucleic Acid Conformation; Nucleic Acid Denaturation; Oligodeoxyribonucleotides; Osmium Tetroxide; Piperidines; Plasmids

We show that chloroacetaldehyde, a chemical compound known to be reactive with unpaired adenine and cytosine residues, reacts with adenine residues (syn conformation) but not with cytosine residues (anti conformation) within Z-DNA. These modified residues are sensitive to cleavage by piperidine, which allows mapping at the single nucleotide level.

Topics: Acetaldehyde; Base Sequence; DNA; Nucleotide Mapping; Piperidines