TY - JOUR
T1 - Base-specific and enantioselective studies for the DNA binding 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 - Wahyuni, Endang Tri
AU - Inoue, Hidenari
AU - Yoshioka, Naoki
N1 - Funding Information:
The first author (M) acknowledges financial support from The Hitachi Scholarship Foundation, Tokyo, Japan through Graduate Support and Collaborative Research Grants. This work is partially supported by Competitive Research Grant (Hibah Bersaing XII/1), contract no.018/P4PT/DPPM/PHB XII/III/2004, 1 March 2004 from The Ministry of National Education, The Republic of Indonesia.
PY - 2007/1
Y1 - 2007/1
N2 - Base specificity and enantioselectivity for the DNA binding of [Fe(phen)2(dppz)]2+ (phen = 1,10-phenanthroline and dppz = dipyrido[3,2-a:2′,3′-c]phenazine) have been studied by determining the equilibrium binding constant (Kb) of the iron(II) complex to calf thymus DNA (ct-DNA), poly[(dA-dT)2], poly[(dG-dC)2] and poly[(dI-dC)2] using spectrophotometric titration and by monitoring the CD spectral profile of the iron(II) complex in the presence and absence of different types of DNA using circular dichroism (CD) spectroscopy, respectively. It has been shown that [Fe(phen)2(dppz)]2+ prefers to intercalate into the A-T and I-C sequences of poly[(dA-dT)2] and poly[(dI-dC)2] rather than into the G-C sequences of poly[(dG-dC)2] or into the base pairs of ct-DNA. In contrast to previous reports, it is a surprising observation that the enantioselectivity of the DNA binding for [Fe(phen)2(dppz)]2+ is base-dependent in nature. The Δ-enantiomer of [Fe(phen)2(dppz)]2+ is preferentially intercalated into the base pairs of poly[(dG-dC)2] or ct-DNA as indicated by its CD spectral profiles. On the other hand, the Λ-enantiomer of [Fe(phen)2(dppz)]2+ is favorably intercalated into poly[(dA-dT)2] or poly[(dI-dC)2] as suggested by the opposite CD spectral profile. This preferential binding of Λ-[Fe(phen)2(dppz)]2+ for the A-T sequence may be attributed to the fact that the binding site for the A-T sequence is relatively facile and thus the steric effect caused by the ancillary (non-intercalated) phen ligands is alleviated. The degree of enantioselectivity represented by inversion constants (Kinv) decreases as the salt concentration in the solution increases, indicating that electrostatic interaction is also operating in the ct-DNA-binding events of the iron (II) complex.
AB - Base specificity and enantioselectivity for the DNA binding of [Fe(phen)2(dppz)]2+ (phen = 1,10-phenanthroline and dppz = dipyrido[3,2-a:2′,3′-c]phenazine) have been studied by determining the equilibrium binding constant (Kb) of the iron(II) complex to calf thymus DNA (ct-DNA), poly[(dA-dT)2], poly[(dG-dC)2] and poly[(dI-dC)2] using spectrophotometric titration and by monitoring the CD spectral profile of the iron(II) complex in the presence and absence of different types of DNA using circular dichroism (CD) spectroscopy, respectively. It has been shown that [Fe(phen)2(dppz)]2+ prefers to intercalate into the A-T and I-C sequences of poly[(dA-dT)2] and poly[(dI-dC)2] rather than into the G-C sequences of poly[(dG-dC)2] or into the base pairs of ct-DNA. In contrast to previous reports, it is a surprising observation that the enantioselectivity of the DNA binding for [Fe(phen)2(dppz)]2+ is base-dependent in nature. The Δ-enantiomer of [Fe(phen)2(dppz)]2+ is preferentially intercalated into the base pairs of poly[(dG-dC)2] or ct-DNA as indicated by its CD spectral profiles. On the other hand, the Λ-enantiomer of [Fe(phen)2(dppz)]2+ is favorably intercalated into poly[(dA-dT)2] or poly[(dI-dC)2] as suggested by the opposite CD spectral profile. This preferential binding of Λ-[Fe(phen)2(dppz)]2+ for the A-T sequence may be attributed to the fact that the binding site for the A-T sequence is relatively facile and thus the steric effect caused by the ancillary (non-intercalated) phen ligands is alleviated. The degree of enantioselectivity represented by inversion constants (Kinv) decreases as the salt concentration in the solution increases, indicating that electrostatic interaction is also operating in the ct-DNA-binding events of the iron (II) complex.
KW - 1,10-Phenanthroline
KW - Base-specificity
KW - DNA-binding
KW - Enantioselectivity
KW - Iron(II)
KW - dppz
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U2 - 10.1016/j.saa.2006.02.037
DO - 10.1016/j.saa.2006.02.037
M3 - Article
C2 - 16822711
AN - SCOPUS:33751547881
SN - 1386-1425
VL - 66
SP - 163
EP - 170
JO - Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
JF - Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
IS - 1
ER -