The binding of proflavine to L)NA has been studied by measuring the polarization and intensity of emission of DNA-dye complexes. Such measurements also permit the determination of the fluorescence of the bound dye as a function of the degree of binding. Techniques of emission spectroscopy permit the
Studies of the optical properties of the proflavine–DNA complex
✍ Scribed by Hsueh Jei Li; Donald M. Crothers
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1969
- Tongue
- English
- Weight
- 873 KB
- Volume
- 8
- Category
- Article
- ISSN
- 0006-3525
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✦ Synopsis
We report studies of the optical properties of the proflavineDNA complex, using absorbance and circular dichroism spectroscopy. From comparison of the absorption spectra of proflavine complexed with calf thymus and T2 DNA, we conclude that stacking of the dyes external to the double helix is comparatively much weaker with T2 DNA, probably because of its glucosylation. Several sources are found for the circular dichroism induced in proflavine when it is complexed with DNA. There is a relatively weak circular dichroism induced when the dye is infinitely dilute on the DNA lattice; this presumably arises from the environmental asymmetry of the binding site. Stronger circular dichroism effects are induced by interaction of intercalated and stacked dyes; studies with T2 DNA, for which stacking seems to be blocked, permit a tentative resolution of effects due to the two modes of binding. One recurring theme of these studies is the observation that the optical properties are quite dependent on environment. The most dramatic example is a strong variation with salt concentration of the amplitude of the circular dichroism induced in the isolated (intercalated) monomer by the surrounding DNA. This suggests that the structure of the intercalated complex is quite sensitive to external conditions.
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The inirinsic viscosity of soiiicated calf thymiis DNA (molecular weight 4-5 X lo5) increases and the sedimentation constant decreases, with increasing binding of proflavine at 0.2 ionic strength and at 25°C. The measiirements correspond to a linear increase in length of the almost rodlike DNA molec
## Abstract The binding isotherm of 2, 7‐di‐__tert__‐butyl proflavine on calf thymus DNA has been measured by dialysis equilibrium. The CD spectra of complexes of the dye and DNA have been measured, and the variation of the induced circular dichroism of the dye with the amount of dye bound (__r__)
The electronic absorption and circular dichroism spectra of the DNA-acridine orange complex have been measured over a range of ionic strength, pH, and DNA phosphate to dye (P/D) ratios. Three circular dichroism bands associated with the long wavelength absorption band of acridine orange are induced
The relation between t,he birefringence dispersion ciirve in a dichroic absorption hand and the corresponding dichroism spectrum is given, rising the Carichy's theorem. The t,heory was checked on a DNA-proflavine complex with the aid of electro-optical measurements. An excellent agreement between th