Structure studies of H2TMpyP4 and ZnTMpyP4 bound to DNA using laser-induced dichroism in solution

Liu, Yixian; Koningstein, J. A.

doi:10.1021/j100125a012

Cited by 15 publications

(8 citation statements)

References 9 publications

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“…Several new conclusions are drawn regarding the (1) analytically and structurally interesting site/sequence specificity of the binding, (2) electronic excited state properties of free and bound PdP(4), (3) perturbation effects of intercalation and external binding on the porphyrin frontier (,*) MOs, and (4) orientation of bound PdP(4) in each of the three B-DNA systems. Our findings are based on a detailed analysis of MCD, CD, and optical (UV-visible) spectra measured in the analytically sensitive porphyrin Soret (B 0 ) band region (⑀ max ϳ 10 5 cm Ϫ1 M Ϫ1 ), in addition to insight gained from previous experimental (e.g., viscosity, [1][2][3][4][5][6] unwinding of supercoiled DNA, 3,6,7 footprinting, 8,9 optical, 1,3,10,11 CD, 1,3,7,10,12 flow linear dichroism (FLD), 4,5,13,14 NMR, 2,4,5,15,16 resonance Raman (RR), [17][18][19][20][21] laser-induced dichroism (LID), 22 and photoluminescence 23 ) and computational 24,25 work on these and similarly bound porphyrin systems. Use is also made of matrix method CD (mm-CD) sector rules, 26,27 based on the nondegenerate electric dipole transition moment (edtm) coupling ( e D Ϫ e DNA ) model, for interpreting the signs of DNA-induced CD bands in drugs that are achiral in the unbound state with transition energies below those of the DNA bases.…”

Section: Introductionmentioning

confidence: 99%

5,10,15,20-Tetrakis(4-N-methylpyridyl)porphyrinatopalladium(II) as a differentiation probe for sensing binding modes with B-DNA duplexes: Electronic MCD and CD spectra

Barnes¹,

Stroud²,

Robinson³

et al. 1999

Biospectroscopy

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We report our detailed electronic MCD, CD, and optical spectroscopic measurements and analysis of the porphyrin Soret (B0) region of four‐coordinate 5,10,15,20‐tetrakis(4‐N‐methylpyridyl)porphyrinatopalladium(II), PdP(4), and its bound states with B‐DNA duplexes poly(A‐T)2, poly(G‐C)2, and calf thymus DNA (CT DNA). For system PdP(4)/poly(A‐T)2 it was possible to conclude that the porphyrin is bound edge‐on in the major groove, specifically at the 5′AT3′ site. For this orientation the porphyrin's electric dipole transition moments (edtm), μx (most perturbed direction) and μy (least perturbed direction), have tilt angles α ∼ 90° and ∼ 45°, respectively, relative to the helix axis. It was further concluded from the small shifts of B0 optical and MCD band intensities and wavelengths and from the net MCD (+) A‐term sign retention upon binding that the porphyrin's frontier pπ MOs (1a1u 3a2u 4eg) are only weakly perturbed by the heterocyclic bases of poly(A‐T)2, and therefore that the LUMO (4eg) splitting is less than the |1a1u−3a2u| energy separation, ΔHOMO, that is, ΔLUMO < ΔHOMO for the bound state in PdP(4)/poly(A‐T)2. For intercalation systems PdP(4)/poly(G‐C)2 and /CT DNA, with PdP(4) centered in the intercalation “pocket” and having two of its 4‐N‐methylpyridyls extending into each of the major and minor grooves, the edtms μx and μy were determined to be oriented perpendicular (γ ∼ 0°) and parallel (γ ∼ 90°) to the hydrogen bonds of the base pairs, respectively. Intercalation is characterized by a much stronger binding interaction, viz., the B0 optical band and net MCD extrema wavelength shifts are relatively large, and the net MCD (+) A‐term of PdP(4) is substantially quenched as it becomes the (−) pseudo‐A‐term of intercalated PdP(4)/poly(G‐C)2. This A‐term sign reversal informs that the porphyrin MOs are so strongly perturbed by the GC base pairs that ΔLUMO > ΔHOMO, which gives rise to a (−) pseudo‐A‐term. Also, the findings demonstrate (1) the potential of PdP(4) as a sensitive, discriminating analytical probe of DNA sequences and (2) the diagnostic capability of the composite of five spectra [net MCD, CD, and optical of free and bound PdP(4)] in differentiating the site and sequence selectivity and preferred binding mode of this porphyrin. © 1999 John Wiley & Sons, Inc. Biospectroscopy 5: 179–188, 1999

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Section: Introductionmentioning

confidence: 99%

5,10,15,20-Tetrakis(4-N-methylpyridyl)porphyrinatopalladium(II) as a differentiation probe for sensing binding modes with B-DNA duplexes: Electronic MCD and CD spectra

Barnes¹,

Stroud²,

Robinson³

et al. 1999

Biospectroscopy

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“…1) and its metallated derivatives present a particular interest due to their very efficient intercalation between the nucleic acid base pairs. 9 The tight porphyrin-DNA binding has been considered as the main reason of the high photosensitizing activity of this cationic porphyrin. 10,11 Although singlet oxygen mediated reactions seem to be dominant in the nucleic acid damage photosensitized by H 2 TMPyP(4), 11 the photophysics of porphyrin bound to either mononucleotides or polynucleotides suggests that a charge transfer process also plays a significant role.…”

Section: Introductionmentioning

confidence: 99%

Femtosecond relaxation processes from upper excited states of tetrakis(N-methyl-4-pyridyl)porphyrins studied by transient absorption spectroscopy

Enescu

Steenkeste

Tfibel

et al. 2002

Phys. Chem. Chem. Phys.

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“…[8][9][10] The absence of axial groups, such as in H 2 TMPyP(4) versus ZnTMPyP, in combination Spectroscopic Data with the type of base pairs, GC versus AT, has been found to play an important role in the interResults on the temperature-dependent intensity calation compared with the external binding proof the fluorescence band of the intercalated and externally bound porphyrin molecule to DNA …”

Section: Experimental and Resultsmentioning

confidence: 99%

Estimation of the complexing parameters for intercalated and externally bound tetrakisporphine to the DNA molecule

Treszczanowicz¹,

Koningstein²

1997

Biospectroscopy

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The results of a temperature‐dependent and time‐dependent fluorescence intensity study of the emission of intercalated and externally bound tetrakis(4‐N‐methylpyridyl)porphine are analyzed in terms of an association model. This analysis allows one to estimate differences in the enthalpies and entropies of complex formation for the intercalated and externally bound porphyrin‐DNA systems. These results indicate that the externally bound porphyrin molecule is more strongly bound to the DNA molecule than is the intercalated porphyrin molecule. © 1997 John Wiley & Sons, Inc. Biospectroscopy 3: 445–448, 1997

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Structure studies of H2TMpyP4 and ZnTMpyP4 bound to DNA using laser-induced dichroism in solution

Cited by 15 publications

References 9 publications

5,10,15,20-Tetrakis(4-N-methylpyridyl)porphyrinatopalladium(II) as a differentiation probe for sensing binding modes with B-DNA duplexes: Electronic MCD and CD spectra

5,10,15,20-Tetrakis(4-N-methylpyridyl)porphyrinatopalladium(II) as a differentiation probe for sensing binding modes with B-DNA duplexes: Electronic MCD and CD spectra

Femtosecond relaxation processes from upper excited states of tetrakis(N-methyl-4-pyridyl)porphyrins studied by transient absorption spectroscopy

Estimation of the complexing parameters for intercalated and externally bound tetrakisporphine to the DNA molecule

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