Noninvasive tracing of recombinant proteins with "fluorophenylalanine-fingers"

High-level residue-specific replacement of phenylalanine residues in recomb inant human annexin V and azurin from Pseudomonas aeruginosa with o-fluorop henylalanine, m-fluorophenylalanine, and p-fluorophenylalanine has been ach ieved using the selective pressure incorporation method, Incorporation was confirmed analytically and by UV spectroscopy while the secondary and terti ary structures of these protein mutants in solution remained unchanged upon the effected substitutions. Fluorinated phenylalanines alone and when inte grated into proteins exhibit two characteristic and prominent shoulders ("f ingers") in the UV spectrum in the range of 260 -270 nm, which do not overl ap with the contributions of tyrosine and tryptophan residues in the protei n UV spectra. Thus, the presence of such "fluorophenylalanine fingers" (''F F fingers'') opens a new spectral window to identify the labeled target pro tein among other nonlabeled cellular proteins in preparative work by simple UV spectroscopy, In the coming era of proteomics such a reliable, cheap, a nd easy reproducible methodology might have a great potential for speeding up the identification and characterization of target molecules in the total protein output from the genomes of a variety of organisms. (C) 2000 Academ ic Press.