Phosphorus-31 NMR spectra of ethidium, quinacrine, and daunomycin complexes with poly(adenylic acid)ter dot poly(uridylic acid) RNA duplex and calf thymus DNA
- Purdue Univ., West Lafayette, IN (USA)
{sup 31}P NMR provides a convenient monitor of the phosphate ester backbone conformational changes upon binding of the intercalating drugs ethidium, quinacrine, and daunomycin to sonicated poly(A){center dot}poly(U) and calf thymus DNA. {sup 31}P chemical shifts can also be used to assess differences in the duplex unwinding angles in the presence of the drug. Thus a new {sup 31}P signal, 1.8-2.2 ppm downfield from the double-stranded helix signals, is observed in the ethidium ion-poly(A){center dot}poly(U) complex. This signal arises from phosphates which are in perturbed environments due to intercalation of the drug. This is in keeping with the hypothesis that the P-O ester torsional angle in phosphates linking the intercalated base pairs is more trans-like. Similar though smaller deshielding of the {sup 31}P signals is observed in sonicated poly(A){center dot}poly(U)-quinacrine complexes as well as in the daunomycin complexes. The effect of added ethidium ion, quinacrine, and daunomycin on the {sup 31}P spectra of sonicated calf thymus DNA is consistent with Wilson and Jones' (1982) earlier study. In these drug-DNA complexes the drug produces a gradual downfield shift in the DNA {sup 31}P signal without the appearance of a separate downfield peak. These differences are attributed to differences in the rate of chemical exchange of the drug between free and bound duplex states. The previous correlation of {sup 31}P chemical shift with drug duplex unwinding angle is confirmed for both the RNA and DNA duplexes.
- OSTI ID:
- 5545542
- Journal Information:
- Biochemistry; (USA), Vol. 28:7; ISSN 0006-2960
- Country of Publication:
- United States
- Language:
- English
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CLATHRATES
CROSS-LINKING
DNA
NMR SPECTRA
OLIGONUCLEOTIDES
RNA
CALVES
CHEMICAL BONDS
CHEMICAL SHIFT
CONFORMATIONAL CHANGES
MOLECULAR STRUCTURE
NUCLEAR MAGNETIC RESONANCE
PHOSPHORUS 31
THYMUS
ANIMALS
BODY
CATTLE
CHEMICAL REACTIONS
DOMESTIC ANIMALS
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LIGHT NUCLEI
LYMPHATIC SYSTEM
MAGNETIC RESONANCE
MAMMALS
NUCLEI
NUCLEIC ACIDS
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PHOSPHORUS ISOTOPES
POLYMERIZATION
RESONANCE
RUMINANTS
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550601* - Medicine- Unsealed Radionuclides in Diagnostics