Structural effects on the circular dichroism of ethidium ion-nucleic acid complexes
Binding of the frameshift mutagen ethidium bromide to eight dinucleoside phosphates of different complementary base sequences, to trinucleoside diphosphates with mismatched bases capable of forming bulged structures (CpUpG and GpUpG + CpC), and to calf thymus DNA at different counterion concentrations was studied by optical methods, notably uv-visible spectroscopy, circular dichroism (CD), and fluorescence-detected circular dichroism (FDCD). The ethidium ion intercalated between the base pairs of the minihelix formed by the complementary dimers and displaced the mismatched bases to form bulged structures with the trimers. Complexes with ribodinucleoside phosphates had larger formation constants than their deoxyribose analogues. At very low ionic strength, complexes of calf thymus DNA plus ethidium ion in different salt concentrations showed that the 307-nm CD magnitude increased with decreasing counterion concentration. Implications of the results for theories of the induced CD spectrum of the ethidium ion are discussed.
- Research Organization:
- Univ. of California, Berkeley
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 6933786
- Journal Information:
- Biochemistry; (United States), Vol. 21:11
- Country of Publication:
- United States
- Language:
- English
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Structural effects on the circular dichroism of ethidium-nucleic acid complexes
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Related Subjects
COMPLEXES
STRUCTURAL CHEMICAL ANALYSIS
DNA
MUTAGENS
NUCLEOSIDES
BROMINATED ALIPHATIC HYDROCARBONS
CALVES
DICHROISM
SPECTROSCOPY
THYMUS
ANIMALS
BODY
CATTLE
DOMESTIC ANIMALS
HALOGENATED ALIPHATIC HYDROCARBONS
LYMPHATIC SYSTEM
MAMMALS
NUCLEIC ACIDS
NUCLEOTIDES
ORGANIC BROMINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANS
RIBOSIDES
RUMINANTS
VERTEBRATES
550200* - Biochemistry