Conformationally Constrained Mono-Fluorinated Arginine as a Cationic Label for Solid-State 19F NMR Analysis of Membrane-Bound Peptides: Conformationally Constrained Mono-Fluorinated Arginine as a Cationic Label for Solid-State 19F NMR Analysis of Membrane-Bound Peptides

A conformationally constrained mono-fluorinated analogue of arginine, (1S,3S)-1-amino-3-fluoro-3-(guanidinomethyl)cyclobutane-1-carboxylic acid (F-CbArg), has been designed as a label for solid-state F-19 NMR spectroscopy. The compound was synthesized and its structural and functional similarity to arginine demonstrated in the context of a representative antimicrobial peptide. The cationic F-19 NMR label was incorporated into the amphiphilic helix of temporin A and provided information on water and phosphate contacts within the lipid environment, thereby demonstrating the utility of F-CbArg in structural studies of membrane-bound peptides.