iHADAMAC: A complementary tool for sequential resonance assignment of globular and highly disordered proteins

An experiment, iHADAMAC, is presented that yields information on the amino-acid type of individual residues in a protein by editing the H-1-N-15 correlations into seven different 2D spectra, each corresponding to a different class of amino-acid types. Amino-acid type discrimination is realized via a Hadamard encoding scheme based on four different spin manipulations as recently introduced in the context of the sequential HADAMAC experiment. Both sequential and intra-residue HADAMAC experiments yield highly complementary information that greatly facilitate resonance assignment of proteins with high frequency degeneracy, as demonstrated here for a 188-residue intrinsically disordered protein fragment of the hepatitis C virus protein NS5A. (C) 2011 Elsevier Inc. All rights reserved.