Observation of Cu-N3- Stretching and N3- Asymmetric Stretching Bands for mono-Azide Adduct of Rhus Vernicifera Laccase

" Mono-azide addeuct of Rhus uernicifera laccase, a multicopper oxidase containing one type-1(blue) copper, one type-2(non-blue normal) copper, and a pair of type-3 (binuclear and EPR silent) copper,of which type-2 and type-3 coppers constitute a trinuclear site, was investigated with resonance Raman(RR) and fourier transform infrared(FT-IR) spectroscopies as a step toward elucidation of the structure and function of the trinuclear site. The Cu-N3- stretching (vCu-N3-) RP band was observed for azide-bound multicopper oxidases for the first time. The vCu-N3- band was located at 400 cm-1 for mono-14N3- laccase, which shifted to 396 cm-1 with the 15N14N14N3- analog. The N3- asymmetric stretching(v(N3-)asym) band was observed by FT-IR spectroscopy at 2035 cm-1 for mono-14N3- laccase and at 2025 cm-1 for the 15N14N14N3- analog. The vCu-N3- and v(N3-)asym frequencies and their 15N14N14N- isotope shifts for azido laccase correspond well with those of metazido hemocyanin, indicating that both derivatives should have a similar binding geometry of azide."