Simultaneous measurement of 1H-15N and Methyl 1Hm-13Cm residual dipolar couplings in large proteins

A two-dimensional TROSY-based SIM-C-13(m)-H-1(m)/H-1-N-15 NMR experiment for simultaneous measurements of methyl D-1(CH) and backbone amide D-1(NH) residual dipolar couplings (RDC) in {U-[N-15,H-2]; Ile delta 1[(CH3)-C-13]; Leu,Val-[(CH3)-C-13/(CD3)-C-12]}-labeled samples of large proteins is described. Significant variation in the alignment tensor of the 82-kDa enzyme Malate synthase G is observed as a function of only slight changes in experimental conditions. The SIM-C-13(m)-H-1(m)/H-1-N-15 data sets provide convenient means of establishing the alignment tensor characteristics via the measurement of D-1(NH) RDCs in the same protein sample.