RESONANCE ASSIGNMENT OF METHIONINE METHYL-GROUPS AND CHI(3) ANGULAR INFORMATION FROM LONG-RANGE PROTON-CARBON AND CARBON-CARBON J-CORRELATION IN A CALMODULIN PEPTIDE COMPLEX

Several simple 3D experiments are used to provide J correlations between methionine C-epsilon methyl carbons and either the (CH2)-H-gamma protons or C-beta and C-gamma. The intensity of the J correlations provides information on the size of the three-bond J couplings and thereby on the chi(3) torsion angle. In addition, a simple 3D version of the HMBC experiment provides a sensitive link between the (CH3)-H-epsilon methyl protons and C-gamma. The methods are demonstrated for a 20 kDa complex between calmodulin and a 26-residue peptide fragment of skeletal muscle myosin light chain kinase.