Conformational studies of the smallest structural motifs of DNA detectable via vibrational circular dichroism: cytidylyl-(3'-5')-guanosine and guanylyl-(3'-5')-cytidine.

The infrared absorption and vibrational circular dichroism (VCD) spectra of buffered aqueous solutions of cytidylyl-(3'-5')-guanosine (5'(CG)3') and guanylyl-(3'-5')-cytidine (5'(GC)3') are reported. Under low ionic strength conditions, these dinucleotides exhibit VCD features that can be predicted qualitatively from structural data of (CG)2 and (GC)2 sequences of poly(dG-dC).poly(dG-dC), using the exciton model for infrared VCD intensities.