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Studies of the Conformational Properties of Dinucleoside Monophosphates and Oligoribonucleotides by Proton Magnetic Resonance


Nelson, James Henry (1969) Studies of the Conformational Properties of Dinucleoside Monophosphates and Oligoribonucleotides by Proton Magnetic Resonance. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/3XNW-2X84.


The structural and conformational properties of several dinucleoside monophosphates and oligonucleotides in aqueous solution have been studied by proton magnetic resonance spectroscopy. Specifically, the role of intramolecular base-stacking interactions and other intramolecular forces in the determination of the conformational properties of these molecules has been investigated; and the results of these studies are discussed in relation to the structural properties of biologically significant nucleic acids.

The proton magnetic resonance spectrum of adenylyl-(3'→5')-adenosine (ApA) was studied as a function of concentration, temperature, solution pH, and concentration of added purine. The results of these studies indicate that the stacking interaction between the two adenine rings in ApA is relatively strong and that the adenine rings are stacked with each of the bases preferentially oriented in the anti conformation as in a similar dApdA (dA = deoxyadenosine) segment in double helical DNA. In the concentration studies, ApA was found to self-associate extensively in aqueous solution via vertical stacking of the planar bases. The purine-binding studies indicate that ApA-purine complexes are formed via purine-adenine base-stacking and evidence was obtained for the formation of a purine-intercalated dinucleotide complex in neutral solution.

Similar proton magnetic resonance studies of adenylyl-(3'→5')-guanosine (ApG) and guanylyl-(3'→5')-adenosine (GpA) indicate that each of these dinucleotides is strongly stacked intramole cularly at 30° and neutral pH with the bases preferentially oriented in the anti conformation. The base-stacking interaction in these molecule s is somewhat weaker than the adenine-adenine base-stacking in ApA. These studies also provided information concerning conformational changes which occur in the ribose rings of the dinucleotides as a result of changes in the intramolecular base-stacking; and this phenomenon is discussed in detail.

The concentration dependence of the proton magnetic resonance spectra of adenylyl-(3'→5')-uridine (ApU) and uridylyl-(3'→5')- adenosine (UpA) has been used to determine the mode of self-association of these dinucleotides and the dimerization equilibrium constant of the self-association process. The binding of 6-methylpurine to ApU was used in additional studies of the nature of purine-dinucleotide complexes and the effect of complex formation on the spectra of these molecules.

Finally, the intramolecular base-stacking inte ractions in ApApA and ApApApA were shown to be comparable to those in ApA. The study of these molecules indicates that each assumes a molecular configuration similar to an analagous segment of double helical DNA.

The results of these studies explicitly demonstrate the importance of base-stacking interactions in determining the conformational properties of nucleic acids and their derivatives in aqueous solution.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Chemistry
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Chan, Sunney I.
Thesis Committee:
  • Unknown, Unknown
Defense Date:28 November 1968
Funding AgencyGrant Number
Record Number:CaltechTHESIS:03232017-153915578
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10103
Deposited By: Benjamin Perez
Deposited On:24 Mar 2017 14:59
Last Modified:09 Nov 2022 19:20

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