Decorating phenylalanine side-chains with triple labeled 13C/19F/2H isotope patterns

We present an economic and straightforward method to introduce C-13-F-19 spin systems into the deuterated aromatic side chains of phenylalanine as reporters for various protein NMR applications. The method is based on the synthesis of [4-C-13, 2,3,5,6-H-2(4)] 4-fluorophenylalanine from the commercially available isotope sources [2-C-13] acetone and deuterium oxide. This compound is readily metabolized by standard Escherichia coli overexpression in a glyphosate-containing minimal medium, which results in high incorporation rates in the corresponding target proteins.