Notes on Synthesis of Perdeutero-5-13C,5,5,5-Trifluoroisoleucine VI56

Abstract

The 13CF3 group is a promising label for heteronuclear (19F,13C) NMR studies of proteins. Desirable locations for this NMR spin label include the branched chain amino acid methyl groups. It is known that replacement of CH3 by CF3 at such locations preserves protein structure and function and enhances stability. 13CF3 may be introduced at the δ position of isoleucine and incorporated biosynthetically in highly deuterated proteins. This paper reports our work in synthesis and purification of 5,5,5-trifluoroisoleucine, its perdeutero and 5-13C versions and of 2-13C-trifluoroacetate and its utility as a precursor for introduction of the 13CF3 group into proteins.