Self-association of 5 '-dAMP in aqueous solution. Profile analysis of the IR band at 1625 cm(-1)

A study of self-association of the mononucleotide 5'dAMP occurring in aqueo us solution is presented. The intense and isolated IR band at 1625 cm(-1), assigned to CN and CC: stretches in the base residue, was chosen for a prof ile analysis. Twenty-three FTIR spectra at concentrations between 0.005 M a nd 0.88 M were used. The number of components inside the profile was determ ined considering the second derivative of the spectra. Curve fittings using Lorentz-Gauss product functions were performed. Three components appear un der the profile, showing a symmetric pattern. The observed splitting could be attributed to dipolar coupling between the vertically stacked base resid ues. The self-association process is detected even at low concentrations. ( C) 1999 Elsevier Science B.V. All rights reserved.