Skip to main content
NCBI home page
Biophysical Journal logoLink to Biophysical Journal
. 1988 Oct;54(4):627–635. doi: 10.1016/S0006-3495(88)82998-9

Perturbations to the intersystem crossing of proflavin upon binding to DNA and poly d(A-IU) from triplet-delayed emission spectroscopy.

W E Lee 1, W C Galley 1
PMCID: PMC1330367  PMID: 3224148

Abstract

The steady-state prompt fluorescence, phosphorescence and delayed fluorescence spectra and triplet lifetimes of free proflavin and proflavin bound to native DNA and alternating poly d(A-IU) were obtained as a function of temperature in a buffer-glycerol solvent. The intensity of the proflavin E-type delayed fluorescence (DF) relative to both the phosphorescence (Ph) and the prompt fluorescence (F) was observed to increase with temperature, and plots of both ln (DF/Ph) and ln (DF/(F.tau T] as a function of 1/T were linear over a wide range of temperatures. Although the activation energies for the thermal repopulation of the proflavin excited singlet state from the triplet obtained from the slopes of these plots were essentially unchanged on binding, perturbations to the S1----T1 intersystem crossing rate constants extracted from the intercepts at infinite temperature were observed. The marked enhancement of the intersystem crossing that occurs with binding to the iodinated polynucleotide reflects an external heavy atom perturbation upon the intercalated dye which also induces a shortening in the triplet lifetime. With proflavin bound to DNA an enhancement to the S1----T1 intersystem crossing, though lesser in magnitude than for poly d(A-IU), is observed but with no change to the triplet lifetime. The well-studied fluorescence quenching of DNA-bound proflavin is a result of this increase in the intersystem crossing. It is proposed that these non-heavy atom enhancements in the intersystem crossing are due to distortions of the molecular plane of the bound proflavin molecule. In total these analyses provide a complete description of the excited state processes of the proflavin molecule and their variations with temperature.

Full text

PDF
627

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Corin A. F., Jovin T. M. Proflavin binding to poly[d(A-T)] and poly[d(A-br5U)]: triplet state and temperature-jump kinetics. Biochemistry. 1986 Jul 15;25(14):3995–4007. doi: 10.1021/bi00362a004. [DOI] [PubMed] [Google Scholar]
  2. Galley W. C., Purkey R. M. Role of heterogeneity of the solvation site in electronic spectra in solution. Proc Natl Acad Sci U S A. 1970 Nov;67(3):1116–1121. doi: 10.1073/pnas.67.3.1116. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Galley W. C., Purkey R. M. Spin-orbital probes of biomolecular structure. A model DNA-acridine system. Proc Natl Acad Sci U S A. 1972 Aug;69(8):2198–2202. doi: 10.1073/pnas.69.8.2198. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Galley W. C., Stryer L. Triplet-singlet energy transfer in proteins. Biochemistry. 1969 May;8(5):1831–1838. doi: 10.1021/bi00833a008. [DOI] [PubMed] [Google Scholar]
  5. Georghiou S. On the nature of interaction between proflavine and DNA. Photochem Photobiol. 1975 Sep-Oct;22(3-4):103–109. doi: 10.1111/j.1751-1097.1975.tb08820.x. [DOI] [PubMed] [Google Scholar]
  6. Hogan M., Wang J., Austin R. H., Monitto C. L., Hershkowitz S. Molecular motion of DNA as measured by triplet anisotropy decay. Proc Natl Acad Sci U S A. 1982 Jun;79(11):3518–3522. doi: 10.1073/pnas.79.11.3518. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. ISENBERG I., LESLIE R. B., BAIRD S. L., Jr, ROSENBLUTH R., BERSOHN R. DELAYED FLUORESCENCE IN DNA-ACRIDINE DYE COMPLEXES. Proc Natl Acad Sci U S A. 1964 Aug;52:379–387. doi: 10.1073/pnas.52.2.379. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. LERMAN L. S. Structural considerations in the interaction of DNA and acridines. J Mol Biol. 1961 Feb;3:18–30. doi: 10.1016/s0022-2836(61)80004-1. [DOI] [PubMed] [Google Scholar]
  9. LERMAN L. S. The structure of the DNA-acridine complex. Proc Natl Acad Sci U S A. 1963 Jan 15;49:94–102. doi: 10.1073/pnas.49.1.94. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Latt S. A., Lalande M., Kunkel L. M., Schreck R., Tantravahi U. Applications of fluorescence spectroscopy to molecular cytogenetics. Biopolymers. 1985 Jan;24(1):77–95. doi: 10.1002/bip.360240108. [DOI] [PubMed] [Google Scholar]
  11. Latt S. A. Microfluorometric detection of deoxyribonucleic acid replication in human metaphase chromosomes. Proc Natl Acad Sci U S A. 1973 Dec;70(12):3395–3399. doi: 10.1073/pnas.70.12.3395. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Parker C. A., Joyce T. A. Prompt and delayed fluorescence of some DNA adsorbates. Photochem Photobiol. 1973 Dec;18(6):467–474. doi: 10.1111/j.1751-1097.1973.tb06451.x. [DOI] [PubMed] [Google Scholar]
  13. Purkey R. M., Galley W. C. Phosphorescence studies of environmental heterogeneity for tryptophyl residues in proteins. Biochemistry. 1970 Sep 1;9(18):3569–3575. doi: 10.1021/bi00820a010. [DOI] [PubMed] [Google Scholar]
  14. Saviotti M. L., Galley W. C. Room temperature phosphorescence and the dynamic aspects of protein structure. Proc Natl Acad Sci U S A. 1974 Oct;71(10):4154–4158. doi: 10.1073/pnas.71.10.4154. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Strambini G. B., Galley W. C. Detection of slow rotational motions of proteins by steady-state phosphorescence anisotropy. Nature. 1976 Apr 8;260(5551):554–556. doi: 10.1038/260554a0. [DOI] [PubMed] [Google Scholar]

Articles from Biophysical Journal are provided here courtesy of The Biophysical Society

RESOURCES