Abstract
The association of neutral analogs of adenine and thymine dinucleoside monophosphates in deuteriochloroform was investigated by infrared spectroscopy. This is the first time that such studies have been done at the dimer level; because of solubility requirements, such experiments could be done only when nucleoside alkyl phosphotriesters became available. Association constants for both self-association and cross-association were determined by analysis of divergence from Beer's law of NH and NH2 stretching bands. The complementary dimers associated with an intrinsic constant of 192 M-1 as compared to a value of 92 M-1 for the corresponding monmers. The relatively low value for the dimers indicates that the association process is not cooperative. The two residues of the dimers behave nearly independently in the association process; therefore, the restriction on the rotation about the bonds of the backbone must be small. This conclusion is discussed in relation to recent reports on unperturbed dimensions of polynucleotides in aqueous solution. The results reinforce the conclusion from the studies on polynucleotides that the restriction of the rotation of the backbone of a polynucleotide in solution cannot be due to steric hindrance alone. Our data support the suggestion that the electrostatic interaction between the charged groups of the polynucleotide backbone and that between the charged groups and water could be the cause of the rigidity of the polynucleotide in a random coil conformation observed in aqueous solution.
Original language | English (US) |
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Pages (from-to) | 720-726 |
Number of pages | 7 |
Journal | Biochemistry |
Volume | 12 |
Issue number | 4 |
DOIs | |
State | Published - Feb 1 1973 |
Externally published | Yes |
ASJC Scopus subject areas
- Biochemistry