Representation of short and long-range handedness in protein structures by signed distance maps

A new representation is proposed of short and long-range handedness in protein structures, by signed distance maps. This representation, based on the co-ordinates of the C alpha atoms of proteins, does not require the assignment of specific regular structures. The short-range handedness along the chain in alpha-helical, beta-strand and turn segments is shown, as well as the handedness between two strands of beta-sheet structures and for crossover connections. Results are given for a beta alpha beta alpha beta folding unit of flavodoxin, a beta alpha beta unit of subtilisin, which contains a left-handed crossover connection, and the domain 1 of bovine beta-trypsin.