FKBP59—Quenching of Tryptophan Fluorescence by Phenylalanine

Another example of tryptophan quenching by nearby amino acid residues is in mutants of HSA. This 64-kDa single-chain protein contains a single tryptophan residue 

C Tip Repressor—Resolution of the Two Interacting Tryptophans by Site-Directed Mutagenesis 

In Section 17.7 we saw the possibility of resolving the emission ectra of individual tryptophan residues using DAS. An ahemadve and more powerful method is to use sitenliiected mutagenesis to create mutant im teins. each with a single trypt han residue. For example, this method has bem applied in studies of the Trp rqn ssOT from E. coH The wild-type protein ctxitains two tryptofirfians 

The difficulties in calculating the DAS are illustrated by the intensity decays (Table 17.6). Bodi the wild-type pro- 

FigMre 1731. Emission spectra of the wQd-QpcK coff Trp repre oc  

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