Resonance Raman spectra have been measured within the S --> Cu charge-transfer band for azurins from Alcaligenes denitrificans, Pseudomonas aeruginosa, and Alcaligenes xylosoxidans. The spectra have similar frequencies but show significantly different intensity patterns. Comparison of the differences in structure and environment from the known X-ray crystal structures with resonance Raman spectral changes demonstrates a rough correlation with the overall protein structure. However, a much better correlation exists between the observed resonance Raman spectral changes and specific amino acid differences. Comparison of the resonance Raman spectra and amino acids within 12 Angstrom of the copper site suggests that the protein-copper site coupling extends to at least 10 Angstrom from the copper. This experimentally observable, long-range coupling with specific amino acids may suggest a new mechanism for the efficient long-range electron transfer seen in these proteins.