Prediction and Analysis Programs

A second widely used sequence-based approach relies on matrices of residue frequencies, pioneered by Parry (1982). He showed that the residue distribution at the seven heptad positions of the putative coiled-coil segments of myosin, tropomyosin, o-keratin, and hemaglutinin are asymmetric, and proposed a method by which the residue frequencies could be used to predict whether a sequence of unknown structure would form a coiled coil. This approach was implemented with modifications in 

Values for the Main Structural Parameters in Coiled Coils with Various Periodicities, Determined Using the Program TWISTER 

Periodicity Number of strands cc radius r0 (A) cc pitch (A) Residue phase ( ) Residues per turn Rise per residue (A) 

1991 O Donoghue and Nilges, 1997), but these are neither more accurate, nor do they have the computational simplicity and elegance of the parametric approach. 

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