Microscope in situ FTIRS studies of CO adsorption on an array of platinum microelectrodes

These bands are attributed to the phenylalanines (Phe), tyrosines (Tyr) and tryptophans (Trp) of the Cu-A domain protein, the band at 258 run is contr ibuted by Phe and others by Tyr and Trp. Excitation above 280 rim. abolishe s the fluorescence emission of Phe, and only exhibits the fluorescence emis sion of Trp in proteins due to Tyr-to-Trp energy transfer and quenching of nearby groups on the peptide chain. Trp emission is very sensitive to the m icroenvironment polarity, and its maximal emission wavelength is not identi cal in different proteins. The Cu-A domain protein has 5 Trp and 8 Tyr fluo rophores, the maximal emission wavelength is 345 nm, which indicates that t here is only a small exposure to the protein surface among these Trp residu es since the free Trp emits at 351 -361 nm, depending on the pH value([11]) . Furthermore, the result is also in agreement with the X-ray structure rep orted for the Paracoccus denitrificans CcO molecule([1]). The fluorescence spectra of this protein had not been reported as far as we have known. The further study on the Cu-A domain is being undertaken.