Figure 5.

Definitions of kink (κ) and wobble (ω) angles. H1 and H2 are the helical axes in vector notation before and after a hinge residue. Boldface is a vector. The identities of specific residues used here to calculate H1 and H2 are given in Methods. The axes do not have to intersect in order to calculate κ as the arccos(H1·H2). The ω is defined as follows. A plane normal to vector H2 is created by the vectors S and C, where C is the normalized distance vector between the C_α atom of the hinge residue and vector H2. The dark spot in the figure is the C_α atom of the hinge residue (either L226, V227, or V227L). S is defined as S = H2 × C. The vector H1 then is projected into the (S,C)-plane to give vector H1′. The angle between H1′ and C is defined as ω.