However, because 310 helices are much more common in the tertiary structures of proteins than pi helices, extension of the Lifson–Roig model to accommodate 310 helices - resulting in a 9x9 transfer matrix when capping is included - has found a greater range of application. Analogous extensions of the Zimm–Bragg model have been put forth but have not accommodated mixed helical conformations.
However, because 310 helices are much more prevalent in the tertiary structures of proteins than pi helices, extension of the Lifson–Roig model to accommodate 310 helices - resulting in a 9x9 transfer matrix when capping is included - has found a broader range of application. Analogous extensions of the Zimm–Bragg model have been proposed but have not accommodated mixed helical conformations.