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^α atoms of proteins, does not require the assignment of specific regular structures. The short-range handedness along the chain in α-helical, β-strand and turn segments is shown, as well as the handedness between two strands of β-sheet structures and for crossover connections. Results are given for a βαβαβ folding unit of flavodoxin, a βαβ unit of subtilisin, which contains a left-handed crossover connection, and the domain 1 of bovine β-trypsin.