Resonance Raman studies of guanine derivatives

Ultraviolet resonance Raman spectra of some guanine derivatives in aqueous solutions are reported, viz. guanosine, N 1 ‐methylguanosine, N 2 ‐methylguanosine and N 2 , N 2 ‐dimethylguanosine. The effects of deuteriation were also investigated. The vibrational patterns of guanosine and the derivatives are complicated, since they involve contributions from both the pyrimidine and imidazole rings. However, the understanding of the spectral features is of special interest since some bands are highly sensitive to the B to Z conformational transition of alternating dG‐dC sequences containing DNA. From these UV resonance Raman spectra, assignments of the principal modes of vibration are proposed and discussed in relation to the results of normal coordinate calculations previously performed by other workers.