Enzymatic incorporation of orthogonally reactive prenylazide groups into peptides using geranylazide diphosphate via protein farnesyltransferase: implications for selective protein labeling.

Protein farnesyltransferase (PFTase) catalyzes the attachment of a geranyl azide moiety to a peptide substrate, N-dansyl-Gly-Cys-Val-Ile-Ala-OH. The resulting azide-containing peptide was derivatized with a triphenylphosphine-based reagent to generate an O-alkyl imidate-linked product, rather than the amide-linked material expected via a Staudinger reaction. Since the CAAX box recognition motif (where the internal A residues are aliphatic amino acids) modified by PFTase can be incorporated into the C-terminus of virtually any polypeptide, this two-step procedure provides a general method for incorporating a diverse range of chemical modifications specifically near the C-terminus of proteins.