Assignment of phosphorus-31 resonances and correlation of chemical shifts with relative electrostatic potential in nucleic acids
The introduction of /sup 17/O into the non-bridging positions of the backbone of polynucleotides induces significant transverse relaxation of the directly bonded phosphorus-31 nucleus. For duplex polynucleotides the primary /sup 17/O induced relaxation mechanism is dipolar whereas for single stranded molecules scalar relaxation of the second kind is dominant. Labeled poly(I) has been complexed with poly(C) to form a duplex. The assignment of individual resonances to poly(I) and poly(C) has been made. Labeled poly(A) was complexed with poly(U) to form the duplex. For this sample each homopolymer contributes half of the intensity of each of the two observed signals. Thus, both homopolymers in the duplex have alternating conformations. Alternating polynucleotide conformations have been observed previously but only for samples with alternating sequences. Labeled Poly(dA-dT) was also prepared and assignment of its /sup 31/P NMR spectrum has been made. The site variation in the electrostatic potential of p(I)-p(C) and p(A)-p(U) has been investigated by examining the increase in the /sup 31/P linewidths induced by the presence of the paramagnetic cations Mn ++ and Co++. The results support the notion that there is correlation of electrostatic potential with /sup 31/P chemical shift as the most downfield /sup 31/P signal is the one most broadened in all cases examined. The electrostatic potential is thought to control the cation binding and solvation of the phosphates and hence to be a determinant of the /sup 31/P chemical shift of polynucleotides.
- Research Organization:
- Wesleyan Univ., Middletown, CT (USA)
- OSTI ID:
- 7246287
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
CATIONS
CHARGED PARTICLES
CHEMICAL SHIFT
COBALT COMPOUNDS
ELECTROSTATICS
EVEN-ODD NUCLEI
IONS
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MANGANESE COMPOUNDS
NUCLEAR MAGNETIC RESONANCE
NUCLEI
NUCLEIC ACIDS
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
OXYGEN 17
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
PHOSPHATES
PHOSPHORUS 31
PHOSPHORUS COMPOUNDS
PHOSPHORUS ISOTOPES
RESONANCE
STABLE ISOTOPES
TRANSITION ELEMENT COMPOUNDS