Applications of Quenching to Proteins

The conformational state of aprotein can have an influence on the exposure of its tryptophan residues to solvent This is illustrated by the cyclic AMP receptor protun (CRP) frcxn Escherichia coli. This protein regulates the expression of over 20 genes in E. coli. CRP consists of two identical polypeptide chains, each containing 209 amino acids. It contains two nonidentical trp residues at positions 13 and 85. 

The intensi decays of protans are ty ucalfy multiexpo-nentiaL Henw, it is natural to fidlow the individual decay ti mes as die uotein is exposed to increasing ccmcoitradcns of quoicha. One ocample is provided by die investigation of the CRP protein just described. FD data for its intrinsic trypt an emission yield decay dmes near 1.5 and 6.8 ns. 

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