Proteins as Sensors

The use of fluorescence for chemical sensing requires h hly spedfic probes. One approach to obtaining the needed specificity is to rely on proteins which are known to bind the desired analyte. This approach has been used to develop sensing proteins for calcium, maltose, and zinc. One senses for zinc was based on a zinc finger peptide. Zinc fingers are part of transcription factors. These proteins bind zinc with high affinity and specificity, the metal typically being bound to histidine and/or cysteine residues. 

An example of a zinc-sensitjve peptide is shown in Hgute 3.46. hi this case, the Zinc finger amino acid sequence was modified to ccmtaui a covalently linked dan l group near the middle of the peptide. Emission spectra of 

1 Longworth, J. W., l97l,Luminescenceofpolypeptidejaiidpcotelns, in Excited States of Proteins and Nucleic Adds, R. R Steiner and 1. Wetnryb (eds.), Plenum Press, New York. pp. 319-484. 

lslick, S. F., 1958, Fluofescoice spectra aiMlpolarizalion of glycer atdehyde 3.pbosphatB and laede dehydrogenase coen me com plexes. J. BkiL Chem, 233 1455-1467. 

Gafioi, A., and Brand, L., 1976. Fluorescence decay studies of reduced racodnamide adenine finudeo(tde in solution and bound to Itva- alcobol dehydrogenase. Biochemistry 15 3165-3171. 

---