The effect of the naturally occurring polyamines spermidine and spermine on poly(amino2-dA-dT).poly(amino2dA-dT) conformation has been studied by UV, CD, and IR spectroscopies. It is shown that a conformational transition is induced in poly(amino2dA-dT).poly(amino2dA-dT) by micromolar concentrations of the polyamines (30 microM) in low-salt aqueous solution. The analysis of our results, in view of previously published studies on conformational properties of the amino polynucleotide, indicates the resulting conformer to be an A-form. Interestingly, the polyamine concentration at the midpoint of the transition is the same in both cases. This provides further evidence that the coordination of positively charged counterions to DNA is determined largely from the DNA structure, probably with an important role for the sequence, and less from the nature of the ions.
|Original language||American English|
|Number of pages||5|
|Publication status||Published - 2 Feb 1993|
- Circular Dichroism
- Nucleic Acid Conformation/drug effects
- Spectrophotometry, Infrared
- Spectrophotometry, Ultraviolet