Selenomethionine, p-cyanophenylalanine pairs provide a convenient, sensitive, non-perturbing fluorescent probe of local helical structure

Abstract

The use of selenomethionine (M_Se)–p-cyanophenylalanine (F_CN) pairs to probe protein structure is demonstrated. M_Se quenches F_CN fluorescence via electron transfer. Both residues can be incorporated recombinantly or by peptide synthesis. Time-resolved and steady-state fluorescence measurements demonstrate that M_Se–F_CN pairs provide specific local probes of helical structure.