I would suggest the single tryptophan protein, azurin, obtained from the bacterium Pseudomonas aeruginosa. Use the apoprotein (with copper removed), it has a large quantum yield. This protein exhibits the bluest tryptophan fluorescence of any protein having an emission maximum of 308 nm. This emission would have a good overlap with the absorption spectrum of tryptophan, thus providing good quenching via Forster energy transfer.
Reference:
Photophysics of metalloazurins.
J E Hansen, J W Longworth, G R Fleming
Biochemistry 09/1990; 29(31):7329-38.
Chris,
Perhaps a better reference than the one I listed above is
Internal Motion and Electron Transfer in Proteins: A Picosecond Fluorescence Study of Three Homologous Azurins, J.W. Petrich, J.W. Longworth and G.R. Fleming, Biochemistry 26, 2711 (1987).
In this paper, the steady-state and time-resolved fluorescence of holoazurin and apoazurins from three bacterial species are compared - that from the species Pseudomonas aeruginosa (Pae), Alcaligenes denitrificans (Ade), and Alcaligenes faecalis (Afe). All three azurins are about 130 amino acids and sharing a very high degree of topological homology. The significant difference among them is the number of tryptophanyl residues and their locations. Azurin Pae has a single tryptophan at the buried position 48, azurin Afe has a single tryptophan at the exposed position 118, and azurin Ade has two tryptophans (one at the buried position 48 and the other at the exposed position 118). The fluorescence of apoazurin Ade demonstrates a fluorescence resonance energy transfer from the buried to exposed tryptophanyl residue.
I hope this is helpful.
Best regards,
John
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