Methyl-detected 'out-and-back' NMR experiments for simultaneous assignments of Alaβ and Ileγ2 methyl groups in large proteins

A set of sensitive methyl-detected 'out-and-back' NMR experiments for simultaneous assignments of Ala beta and Ile gamma 2 methyl positions in large proteins is described. The developed methodology is applied to an 82-kDa enzyme Malate Synthase G. Complete alanine beta and isoleucine gamma 2 H-1-C-13 methyl chemical shift assignments could be obtained from the set of new methyl-detected 'out-and-back' 3D experiments. The described methodology for methyl assignments should be applicable to protein molecules within approximately 100-kDa molecular weight range irrespective of the labeling strategy chosen to produce selectively protonated Ala beta and Ile gamma 2 (CH3)-C-13 sites on a deuterated background.