| Abstract
| - A correlation of the changes in vibrational absorption and vibrational circular dichroism (VCD) spectral featureswith the structural changes of polyriboadenylic acid (polyA) as a function of pH is reported. Analysis of thesolution spectral data as a function of pH led us to establishing the importance of a previously unrecognizedabsorption band at ∼1665 cm-1. The present studies indicate that this absorption band and associated VCDoriginate from the double-helical structure of polyA. The observed changes in solution-state VCD featuresare indicative of the pH-dependent transitions among the three acidic forms of polyA (A, B, and “frozen”form). In addition to the solution-state spectral data, pH-dependent absorption and VCD spectra for films ofpolyA, derived from dilute H2O solutions, are also presented. The pH-dependent changes in the absorptionand VCD spectra of films are also correlated to the polyA structural changes.
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