Structural characterization of a carbon monoxide adduct of a heme-DNA complex.
The structure of a carbon monoxide (CO) adduct of a complex between heme and a parallel G-quadruplex DNA formed from a single repeat sequence of the human telomere, d(TTAGGG), has been characterized using ¹H and ¹³C NMR spectroscopy and density function theory calculations. The study revealed that the heme binds to the 3'-terminal G-quartet of the DNA though a π-π stacking interaction between the porphyrin moiety of the heme and the G-quartet. The π-π stacking interaction between the pseudo-C₂-symmetric heme and the C₄-symmetric G-quartet in the complex resulted in the formation of two isomers possessing heme orientations differing by 180° rotation about the pseudo-C₂ axis with respect to the DNA. These two slowly interconverting heme orientational isomers were formed in a ratio of approximately 1:1, reflecting that their thermodynamic stabilities are identical. Exogenous CO is coordinated to heme Fe on the side of the heme opposite the G-quartet in the complex, and the nature of the Fe-CO bond in the complex is similar to that of the Fe-CO bonds in hemoproteins. These findings provide novel insights for the design of novel DNA enzymes possessing metalloporphyrins as prosthetic groups.
Department of Chemistry, University of Tsukuba, Japan.
Kaori
K
Saito
Hulin
H
Tai
Masashi
M
Fukaya
Tomokazu
T
Shibata
Ryu
R
Nishimura
Saburo
S
Neya
Yasuhiko
Y
Yamamoto
D002248:Carbon Monoxide / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D054856:G-Quadruplexes; D006418:Heme / Q000737:chemistry*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D011789:Quantum Theory
D006418:Heme; D002248:Carbon Monoxide; D004247:DNA