Evidence for concerted motions is also strong for the two leucines, L8 and L67. While we do not probe directly the motion around the Cα–Cβ torsional angle from methyl group RDCs, this angle is still reflected in both of the δ-methyl groups. From the minimum search, we find that, in L8 where all three χ1 rotamers are present, χ2 prefers being in the g+ and g− positions when χ1 is in g+ (populations: 0.54 and 0.44) or tr (populations: 0.41 and 0.57), but prefers being in tr when χ1 is in g− (population: 0.66). Similarly in L67, three different distributions of tr, g+ and g− rotamers of χ2 are observed depending on the state of χ1.