Azurins Raman spectra

The following amino acids have been definitely excluded as part of a common structure of the Type 1 center Tryptophan has been eliminated as a ligand for the reasons given in Section IIAl. Arginine is absent in the plastocyanins. Tyrosine has been eliminated by optical absorption studies of azurin and by a recent analysis of the resonance enhanced Raman spectrum of stellacyanin 206). 

Andrew CR, Han J, den Blaauwen T et al (1997) Cysteine ligand vibrations are responsible for the complex resonance Raman spectrum of azurin. Journal of Bioinorganic Chemistry 2 98-107. 

Figure 12 Vibrational enhancement selectivity available from resonance Raman spectroscopy. The UV-visible spectrum of a P. aeruginosa azurin is shown together with two different Raman spectra (frozen solution at 77 K) that derive from laser excitation within theS(Cys) — Cu(II) charge-transfer absorption band at 625nm (647.1 nm) and away from the absorption (488.Onm). Excitation within resonance leads to dramatically increased Raman scattering from the Cu active site, whereas off-resonance excitation produces a spectrum dominated by bands...

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