Structural effects on the circular dichroism of ethidium ion-nucleic acid complexes

Journal Article · Tue May 25 04:00:00 EDT 1982 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00540a024· OSTI ID:6933786

Dahl, K S; Pardi, A; Tinaco, I Jr

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), Journal Name: Biochemistry; (United States) Vol. 21:11; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
BODY
BROMINATED ALIPHATIC HYDROCARBONS
CALVES
CATTLE
COMPLEXES
DICHROISM
DNA
DOMESTIC ANIMALS
HALOGENATED ALIPHATIC HYDROCARBONS
LYMPHATIC SYSTEM
MAMMALS
MUTAGENS
NUCLEIC ACIDS
NUCLEOSIDES
NUCLEOTIDES
ORGANIC BROMINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANS
RIBOSIDES
RUMINANTS
SPECTROSCOPY
STRUCTURAL CHEMICAL ANALYSIS
THYMUS
VERTEBRATES