TY - JOUR
T1 - DNA-binding properties of iron(II) mixed-ligand complexes containing 1,10-phenanthroline and dipyrido[3,2-a:2′,3′-c]phenazine
AU - Mudasir,
AU - Wijaya, Karna
AU - Tjahjono, Daryono H.
AU - Yoshioka, Naoki
AU - Inoue, Hidenari
N1 - Funding Information:
The first author acknowledges financial support from The Hitachi Scholarship Foundation, Tokyo, Japan through the Postdoctoral Research Fellowship Program. This work was partially supported by a Grant-in-Aid for Scientific Research (No. 13554025) from the Ministry of Education, Culture, Sports, Science and Technology, Japan and by Competitive Research Grant (Hibah Bersaing X/2), contract no. 18/P2IPT/DPPM/PHBL/III/2003, 27 March 2003 from The Ministry of National Education, The Republic of Indonesia.
PY - 2004/3
Y1 - 2004/3
N2 - An iron(II) mixed-ligand complex with 1,10-phenanthroline (phen) and dipyrido[3,2-a:2′,3′-c]phenazine (dppz), [Fe(phen) 2(dppz)]2+, has been synthesized. The DNA-binding properties of the mixed-ligand complex have been studied in terms of equilibrium binding constant, thermodynamic parameter, thermal denaturation as well as Pfeiffer effect upon binding to DNA. The spectrophotometric titration of [Fe(phen)2(dppz)]2+ with calf thymus DNA (ct-DNA) has shown that the iron(II) mixed-ligand complex binds effectively to ct-DNA in an intercalation mode as indicated by remarkable hypochromicity (ca. 36%) and moderate bathochromic shift (8 nm) of the absorption spectra. This intercalative mode is supported by a significant increase (ΔTm = 21°C) in the melting temperature (Tm) of ct-DNA at R([complex]/[ct-DNA]) = 1.5. The binding of [Fe(phen)2(dppz)]2+ to ct-DNA is entropically driven as characterized by a positive enthalpy change and a large negative T Δ S term. An intense CD signal in the UV and visible region develops upon addition of ct-DNA to the racemate solution of [Fe(phen) 2(dppz)]2+. This has revealed that a shift in diastereomeric inversion equilibrium takes place in the solution to yield an excess of one enantiomer of the DNA-iron(II) complex (Pfeiffer effect). The striking resemblance of the CD spectral profiles to those of the corresponding Δ-enantiomer indicates that Δ-[Fe(phen)2(dppz)] 2+ is preferentially bound to ct-DNA.
AB - An iron(II) mixed-ligand complex with 1,10-phenanthroline (phen) and dipyrido[3,2-a:2′,3′-c]phenazine (dppz), [Fe(phen) 2(dppz)]2+, has been synthesized. The DNA-binding properties of the mixed-ligand complex have been studied in terms of equilibrium binding constant, thermodynamic parameter, thermal denaturation as well as Pfeiffer effect upon binding to DNA. The spectrophotometric titration of [Fe(phen)2(dppz)]2+ with calf thymus DNA (ct-DNA) has shown that the iron(II) mixed-ligand complex binds effectively to ct-DNA in an intercalation mode as indicated by remarkable hypochromicity (ca. 36%) and moderate bathochromic shift (8 nm) of the absorption spectra. This intercalative mode is supported by a significant increase (ΔTm = 21°C) in the melting temperature (Tm) of ct-DNA at R([complex]/[ct-DNA]) = 1.5. The binding of [Fe(phen)2(dppz)]2+ to ct-DNA is entropically driven as characterized by a positive enthalpy change and a large negative T Δ S term. An intense CD signal in the UV and visible region develops upon addition of ct-DNA to the racemate solution of [Fe(phen) 2(dppz)]2+. This has revealed that a shift in diastereomeric inversion equilibrium takes place in the solution to yield an excess of one enantiomer of the DNA-iron(II) complex (Pfeiffer effect). The striking resemblance of the CD spectral profiles to those of the corresponding Δ-enantiomer indicates that Δ-[Fe(phen)2(dppz)] 2+ is preferentially bound to ct-DNA.
KW - DNA Binding
KW - Dppz
KW - Iron(II)
KW - Mixed Ligand Complex
KW - Phenanthroline
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U2 - 10.1515/znb-2004-0313
DO - 10.1515/znb-2004-0313
M3 - Article
AN - SCOPUS:1942423083
SN - 0932-0776
VL - 59
SP - 310
EP - 318
JO - Zeitschrift fur Naturforschung - Section B Journal of Chemical Sciences
JF - Zeitschrift fur Naturforschung - Section B Journal of Chemical Sciences
IS - 3
ER -