From Genome to Life:

FIRNEIS Friedrich

Austrian Academy of Sciences, Computer Center, Dr. Ignaz-Seipelplatz 2, Vienna A1010, Austria

title: Usage of Quaternions in Protein Structure Assessment.

F. Firneis, E. Horniakova

For the rotation of subunits of proteins on computers, usually Eulerian angles are used. However this approach is not intuitively geometric. Unit quaternions can be used for advantage, to rotate a given substructure along an axis freely chosen. If for rotation angles not only real numbers but dual numbers are used, rotation plus translation can be packed into a set of compact formulas to describe screw motion, a basic element of fhreedimensional kinematics.