An optimized isotopic labelling strategy of isoleucine-γ 2 methyl groups for solution NMR studies of high molecular weight proteins

An efficient synthetic route is proposed to produce 2-hydroxy-2-ethyl-3-oxobutanoate for the specific labelling of Ile methyl-γ(2) groups in proteins. The (2)H, (13)C-pattern of the biosynthetic precursor has been designed to optimize magnetization transfer, in large proteins, between these important structural probes and their corresponding backbone nuclei.