Fluorescence‐free resonance Raman spectra of reduced nicotinamide adenine dinucleotide via ultraviolet excitation

Excitation of reduced nicotinamide adenine dinucleotide (NADH) on the high‐energy side (333.6 nm) of its ultraviolet absorption band shifts the Raman scattering away from the fluorescence band and produces a good quality resonance Raman spectrum. It is dominated by the amide I (CO stretch) mode, at 1687 cm−1, but several weaker bands are observed, and are tentatively assigned to amide II and III, and ring modes, consistent with N2H2 and 4‐2H isotope shifts. An identical spectrum is observed for nicotinamide mononucleotide (NMNH), indicating that the adenine and nicotinamide portions of NADH do not interact.