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The Wenxiang diagram, also known as the Wenxiang graph, was proposed in 1997 for helping intuitively analyze the disposition of amphiphilic alpha helices in heteropolar environments It is closely related to the earlier 2D diagram called a "helical wheel", which is a slightly idealized projection of the Calphas down the helix axis, also with one-letter-code labels and color-coded symbols to show the sequence and its properties. This diagram is called “wenxiang” because of its shape that resembles the coil-like incense widely used in old China to repel mosquitoes, called 蚊香 and pronounced as "wenxiang".
Because the wenxiang diagram is generated by a conical projection of a helix onto a plane, with the start (N-terminus) of the helix at the edge and the end toward the center, the location of each residue in a helix is not only defined by an angle around the diagram’s center, but is also defined by its radius from the center of the diagram in number of turns, which corresponds to its distance along the helix, in number of turns. Therefore, in principle, the wenxiang diagram can be used to represent an alpha-helix of any length. The example shown is quite long, with 7 turns and sequence NIAEAVQQLNHTIVNAAHELHETLGL; its hydrophobic side is in red and its hydrophilic side in blue.
Wenxiang diagrams have been used to study helix-helix interactions and protein-protein interactions.