title: A study of 7-deaza-2'-deoxyguanosine 2'-deoxycytidine base pairing in DNA.
abstract: The incorporation of 7-deazaguanine modifications into DNA is frequently used to probe protein recognition of H-bonding information in the major groove of DNA. While it is generally assumed that 7-deazaguanine forms a normal Watson-Crick base pair with cytosine, detailed thermodynamic and structural analyses of this modification have not been reported. The replacement of the 7-N atom on guanine with a C-H, alters the electronic properties of the heterocycle and eliminates a major groove cation-binding site that could affect the organization of salts and water in the major groove. We report herein the characterization of synthetic DNA oligomers containing 7-deazaguanine using a variety of complementary approaches: UV thermal melting, differential scanning calorimetry (DSC), circular dichroism (CD), chemical probing and NMR. The results indicate that the incorporation of a 7-deazaguanine modification has a significant effect on the dynamic structure of the DNA at the flanking residue. This appears to be mediated by changes in hydration and cation organization.
authors.affiliation: Eppley Institute for Research in Cancer, Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, NE-68198-6025, USA.
authors.forename: Manjori
authors.initials: M
authors.lastname: Ganguly
authors.forename: Feng
authors.initials: F
authors.lastname: Wang
authors.forename: Mahima
authors.initials: M
authors.lastname: Kaushik
authors.forename: Michael P
authors.initials: MP
authors.lastname: Stone
authors.forename: Luis A
authors.initials: LA
authors.lastname: Marky
authors.forename: Barry
authors.initials: B
authors.lastname: Gold
mesh_terms: D020029:Base Pairing; D002152:Calorimetry, Differential Scanning; D002412:Cations / Q000737:chemistry; D002942:Circular Dichroism; D003596:Cytosine / Q000737:chemistry; D004247:DNA / Q000737:chemistry*; D003841:Deoxycytidine / Q000737:chemistry*; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000737:chemistry; D006860:Hydrogen Bonding; D019906:Nuclear Magnetic Resonance, Biomolecular; D009690:Nucleic Acid Conformation; D013056:Spectrophotometry, Ultraviolet; D055672:Static Electricity; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D002412:Cations; D014867:Water; D003841:Deoxycytidine; C045550:7-deaza-2'-deoxyguanosine; D003596:Cytosine; D004247:DNA; D003849:Deoxyguanosine