We consider a problem which is part of the process of determining the three-dimensional structure of a protein molecule using X-ray crystallography: given an estimated map of the electron density of the molecule as a function on three-dimensional space, we identify regions which are likely to belong to -helices. Our approach is to compute a new kind of skeleton the power shape and then identify...

Helically coiled filaments are a frequent motif in nature. In situations commonly encountered in experiments coiled helices are squeezed flat onto two dimensional surfaces. Under such 2-D confinement helices form ”squeelices” peculiar squeezed conformations often resembling looped waves, spirals or circles. Using theory and Monte-Carlo simulations we illuminate here the mechanics and the unusua...

We describe a new computer program that identifies conserved secondary structures in aligned nucleotide sequences of related single-stranded RNAs. The program employs a series of hash tables to identify and sort common base paired helices that are located in identical positions in more than one sequence. The program gives information on the total number of base paired helices that are conserved...

We present a method for the computer-based iterative assembly of native-like tertiary structures of helical proteins from alpha-helical fragments. For any pair of helices, our method, called MATCHSTIX, first generates an ensemble of possible relative orientations of the helices with various ways to form hydrophobic contacts between them. Those conformations having steric clashes, or a large rad...