title: Alteration in DNA binding pattern of conformationally locked NC(O)N system: A spectroscopic investigation.
abstract: The binding mode of a conformationally locked NC(O)N planar system with deoxyribonucleic acid (DNA) is investigated using various spectroscopic and enzymatic assays. Compound 1 and its four different salts (comp. 2-5) were prepared for this purpose. They showed certain changes in their respective DNA-compound complex at ground state and excited state as measured by UV-vis and fluorescence emission spectra. The Stern-Volmer quenching constant (KSV) for the neutral species (1) is found 8545 M(-1), whereas, for its salts 2, 3, 4 and 5 the quenching constants were 33510 M(-1), 11352 M(-1), 19693 M(-1) and 27270 M(-1) respectively. Nevertheless, the binding constant values remain comparable in neutral and salt forms except for 5. To elucidate the reason we took their CD spectra and ran a topoisomerase I (Topo I) assay. These experimental data revel the fact that compound 1 (neutral form) binds at the minor groove of DNA, whereas, its salt (2) has an extended intercalating property.
authors.affiliation: Department of Chemistry, SASTRA University, Thanjavur 613401, India.
authors.forename: Anand Babu
authors.initials: AB
authors.lastname: Velappan
authors.affiliation: Department of Chemistry, Indian Institute of Technology Patna, Patna 800013, India.
authors.forename: Banibrata
authors.initials: B
authors.lastname: Maity
authors.affiliation: Department of Chemistry, State University of New York at Geneseo, 1 College Circle, Geneseo, NY 14454, USA.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Kasper
authors.affiliation: Department of Chemistry, State University of New York at Geneseo, 1 College Circle, Geneseo, NY 14454, USA. Electronic address: mcknight@geneseo.edu.
authors.forename: Ruel E
authors.initials: RE
authors.lastname: McKnight
authors.affiliation: Department of Chemistry, Indian Institute of Technology Patna, Patna 800013, India. Electronic address: debrabata@iitp.ac.in.
authors.forename: Debabrata
authors.initials: D
authors.lastname: Seth
authors.affiliation: Department of Chemistry, SASTRA University, Thanjavur 613401, India. Electronic address: joydebnath@scbt.sastra.edu.
authors.forename: Joy
authors.initials: J
authors.lastname: Debnath
mesh_terms: D000818:Animals; D002942:Circular Dichroism; D004264:DNA Topoisomerases, Type I / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000737:chemistry; D008968:Molecular Conformation; D009841:Oligonucleotides / Q000737:chemistry*; D011485:Protein Binding; D013057:Spectrum Analysis / Q000379:methods
chemical_list: D004268:DNA-Binding Proteins; D009841:Oligonucleotides; C477371:locked nucleic acid; D004264:DNA Topoisomerases, Type I
keywords: Circular dichroism; Deoxyribonucleic acid; Fluorescence; Stern–Volmer quenching constant; Topoisomerase I