title: Interaction between the heme and a G-quartet in a heme-DNA complex.
abstract: The structure of a complex between heme(Fe(3+)) and a parallel G-quadruplex DNA formed from a single repeat sequence of the human telomere, d(TTAGGG), has been characterized by (1)H NMR. The study demonstrated that the heme(Fe(3+)) is sandwiched between the 3'-terminal G-quartets of the G-quadruplex DNA. Hence, the net +1 charge of the heme(Fe(3+)) in the complex is surrounded by the eight carbonyl oxygen atoms of the G-quartets. Interaction between the heme Fe(3+) and G-quartets in the complex was clearly manifested in the solvent (1)H/(2)H isotope effect on the NMR parameters of paramagnetically shifted heme methyl proton signals, and interaction of the heme Fe(3+) with the eight carbonyl oxygen atoms of the two G-quartets was shown to provide a strong and axially symmetric ligand field surrounding the heme Fe(3+), yielding a heme(Fe(3+)) low-spin species with a highly symmetric heme electronic structure. This finding provides new insights as to the design of the molecular architecture and functional properties of various heme-DNA complexes.
authors: Department of Chemistry, University of Tsukuba, Tsukuba 305-8571, Japan.
authors: Kaori
authors: K
authors: Saito
authors: Hulin
authors: H
authors: Tai
authors: Hikaru
authors: H
authors: Hemmi
authors: Nagao
authors: N
authors: Kobayashi
authors: Yasuhiko
authors: Y
authors: Yamamoto
mesh_terms: D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry*; D054856:G-Quadruplexes; D006418:Heme / Q000737:chemistry*; D006801:Humans; D007501:Iron / Q000737:chemistry*; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D010100:Oxygen / Q000737:chemistry*; D011522:Protons; D012091:Repetitive Sequences, Nucleic Acid; D055672:Static Electricity
chemical_list: D008024:Ligands; D011522:Protons; D006418:Heme; D004247:DNA; D007501:Iron; D010100:Oxygen