Recent Progresses in Studying Helix-Helix Interactions in Proteins by Incorporating the Wenxiang Diagram into the NMR Spectroscopy

All residues in an alpha helix can be characterized and dispositioned on a 2D the wenxiang diagram, which possesses the following features: (1) the relative locations of the amino acids in the a-helix can be clearly displayed regardless how long it is; (2) direction of an alpha-helix can be indicated; and (3) more information regarding each of the constituent amino acid residues in an alpha helix. Owing to its intuitionism and easy visibility, wenxiang diagrams have had an immense influence on our understanding of protein structure, protein-protein interactions, and the effect of helical structural stability on protein conformational transitions. In this review, we summarize two recent applications of wenxiang diagrams incorporating NMR spectroscopy in the researches of the coiled-coil protein interactions related to the regulation of contraction or relaxation states of vascular smooth muscle cells, and the effects of a-helical stability on the protein misfolding in prion disease, in hopes that the gained valuable information through these studies can stimulate more and more widely applications of wenxiang diagrams in structural biology.