Conformational peculiarities of polynucleotides with a nonrandom base sequence according to the 1H----3H exchange rate in C8H groups of purinic residues

Journal Article · Tue Dec 01 04:00:00 EST 1987 · Journal of Biomolecular Structure and Dynamics; (USA)

DOI:https://doi.org/10.1080/07391102.1987.10506415· OSTI ID:7027335

Lesnik, E A; Maslova, R N; Agranovich, I M; Varshavsky, Ya M ^[1]

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1. Institute of Molecular Biology, Moscow (USSR)

We have determined the 1H----3H exchange rate constants between water and C8H groups of purinic residues of alternating polynucleotides poly(dA-dT).poly(dA-dT), poly(dG-dC).poly(dG-dC) and poly(dA-dC).poly(dG-dT) as well as homopolynucleotides poly(dA).poly(dT) and poly(dG).poly(dC) in aqueous solutions with high-salt concentrations (3 M NaCl and 4-6 M CsF), in water-ethanol (60%) solution and in 0.15 M NaCl at 25 degrees C. The rate constants for adenine (kA) and guanine (kG) of polynucleotides were compared with corresponding constants for E. coli DNA. dGMP nd dAMP at the same conditions. The relation between exchange rates and conformations of polynucleotides permits the study of their conformational peculiarities in solution. Of three alternating polynucleotides examined in 0.15 M NaCl the exchange retardation was observed only for poly(dA-dT).poly(dA-dT) as compared with that in B-DNA, which is in good agreement with the B-alternating wrinkled DNA model. The conformations of poly(dG-dC).poly(dG-dC) and poly(dA-dC).poly(dG-dT), according to the exchange data obtained are within the B form. For homopolynucleotides in 0.15 M NaCl, the KA value for poly(dA).poly(dT) is nearly the same as kA for B-DNA, which indicates the similarity of their conformations, whereas the kG value for poly(dG).poly(dC) is 1.7-fold lower in comparison with the kG value in B-DNA. The increase of NaCl concentration to 3 M results in a B----Z transition in the case of poly(dG-dC).poly(dG-dC) and in the shift of B = A equilibrium towards the A-form in the case of poly(dG).poly(dC) as is evidenced by alterations of their KG values. Poly(dA-dT).poly(dA-dT) in 6 M CsF and poly(dA-dC).poly(dG-dT) in 4.3 M CsF maintain their inherent conformations in 0.15 M NaCl in spite of the fact that they are characterised by the X-type CD-spectrum at these conditions.

• OSTI ID: 7027335
• Journal Information: Journal of Biomolecular Structure and Dynamics; (USA), Journal Name: Journal of Biomolecular Structure and Dynamics; (USA) Vol. 5:3; ISSN 0739-1102; ISSN JBSDD
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AQUEOUS SOLUTIONS
AROMATICS
AZAARENES
BARYONS
DISPERSIONS
ELEMENTARY PARTICLES
FERMIONS
HADRONS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
ISOTOPE APPLICATIONS
MIXTURES
MOLECULAR STRUCTURE
NUCLEONS
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PROTONS
PURINES
SOLUTIONS
TRACER TECHNIQUES
TRITIUM COMPOUNDS