We recently reported a direct technique for determining the binding sites of small molecules on naturally occurring heterogeneous DNA (Van Dyke et al. 1982). Methidiumpropyl-EDTA.Fe(lI) (MPE.Fe[I~) (Hertzberg and Dervan 1982) cleaves double-helical DNA with low sequence-specificity (Van Dyke et al. 1982). Using a combination of MPE-Fe(II) partial cleavage of drugprotected DNA fragments and Maxa...

In this study, a nickel (II) complex with 1,10-phenanthroline based ligand, [Ni(FIP)2](OAC)2 (1) with FIP = 2-(Furan-2-yl)-1H-Imidazole[4,5-f][1,10] phenanthroline as ligand was synthesized and characterized by spectroscopic methods and elemental analysis. The interaction of [Ni(FIP)2](OAC)2 (1) with calf-thymus DNA (ct-DNA) was studied by UV-vis absorption, fluorescence spectroscopies and visc...

A colorimetric assay of sequence-specific DNA cleavage by bleomycin (BLM) derivatives is a promising methodology for facilitating the development DNA-associated drugs with antitumor activity. Double-stranded DNA-functionalized gold nanoparticles (dsDNA-AuNPs) possessing BLM-mediated sites were designed. The front cover highlights non-fluorescence-based analytical method that allows visual scree...

LysR-type transcription regulators (LTTRs) comprise one of the largest families transcriptional in bacteria. They are typically homo-tetrameric proteins and interact with promoter DNA ~ 50–60 bp. Earlier biochemical studies have suggested that LTTR binding to bends and, upon inducer binding, bend angle is reduced through a quaternary structure change tetrameric LTTR, leading activation transcri...

Topoisomerase II resolves intrinsic topological problems of double-stranded DNA. As part of its essential cellular functions, the enzyme generates DNA breaks, but the regulation of this potentially dangerous process is not well understood. Here we report single-molecule fluorescence experiments that reveal a previously uncharacterized sequence of events during DNA cleavage by topoisomerase II: ...

The Borrelia telomere resolvase, ResT, forms the unusual hairpin telomeres of the linear Borrelia replicons in a process referred to as telomere resolution. Telomere resolution is a DNA cleavage and rejoining reaction that proceeds from a replicated telomere intermediate in a reaction with mechanistic similarities to that catalyzed by type IB topoisomerases. Previous reports have implicated the...

Specialized type I topoisomerases catalyze DNA strand transfer during site-specific recombination in prokaryotes and fungi. As a rule, the site specificity of these systems is determined by the DNA binding and cleavage preference of the topoisomerase per se. The Mr 32,000 topoisomerase I encoded by vaccinia virus (a member of the eukaryotic family of "general" type I enzymes) is also selective ...

Positively charged trimethylammonium-modified mixed monolayer protected clusters (MMPCs) interact with DNA by complementary electrostatic binding, serving as efficient DNA delivery systems. The stability of gold nanoparticle-bound DNA toward biological, physical, and chemical agents is investigated. The MMPC-bound DNA is efficiently protected from DNAse I digestion and experiences nicking/cleav...

Type II topoisomerases (Top2s) alter DNA topology via the formation of an enzyme-DNA adduct termed cleavage complex, which harbors a transient double-strand break in one DNA to allow the passage of another. Agents targeting human Top2s are clinically active anticancer drugs whose trapping of Top2-mediated DNA breakage effectively induces genome fragmentation and cell death. To understand the st...