Effects of ribosylnucleotide substitution and methylation on the structure of synthetic polynucleotides

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1985

OSTI ID:6523210

Wu, H Y

The A conformation of Poly (rG-dC).Poly(rD-dC) in normal salt conditions is confirmed by its circular dichroic, Raman and NMR spectra. Its characteristic Z-A-Z transition from a very low salt conditions (5 mM Tris-HCl) to a high salt condition is also described. In addition, the synthesis of the DNA copolymer Poly (rG-m/sup 5/ dC).Poly (rG-m/sup 5/ dC) provides an opportunity to study the effect of C-5 position methyl groups on the salt induced conformational transition. The high salt A to Z transition point of Poly (rG-m/sup 5/ dC).Poly (rG-m/sup 5/ dC) still remains at the 1-2 M NaCl concentration range, unlike the effect of the C-5 position methyl groups on Poly (dG-dc).Poly (dG-dc), which lowers the B to Z transition point from 2.5 M to 0.7 M. The C-5 position methyl group on pyrimidine bases has another effect on DNA structure. Both Poly (rG-m/sup 5/ dC).Poly (rG-m/sup 5/ dC) and Poly (dG-m/sup 5/ dC).Poly (dG m/sup 5/ dC) have an alternating structure under normal salt conditions. Two closely spaced but distinct peaks in their /sup 31/P NMR spectra indicate two different phosphate atom environments. The same phenomenon is also seen in the /sup 31/P NMR spectrum of Poly (dA-dT).Poly (dA-dT); the C-5 position methyl group is also present on the thymidine residues. It is obvious that the C-5 position methyl groups somehow effect the stacking of nucleotide bases which alters the phosphodiester torsional angle. This characteristic is true of every two nucleotide bases. The results show that Hha I methylase works better on the A form than B form.

• Research Organization: City Univ. of New York, NY (USA)
• OSTI ID: 6523210
• Country of Publication: United States
• Language: English

Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
CHEMICAL REACTIONS
DNA
ISOTOPES
LASER SPECTROSCOPY
LIGHT NUCLEI
MAGNETIC RESONANCE
METHYLATION
MOLECULAR STRUCTURE
NUCLEAR MAGNETIC RESONANCE
NUCLEI
NUCLEIC ACIDS
NUCLEOTIDES
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PHOSPHORUS 31
PHOSPHORUS ISOTOPES
RAMAN SPECTROSCOPY
RESONANCE
SPECTROSCOPY
STABLE ISOTOPES