INTERCHAIN PACKING ENERGIES OF MULTISTRANDED ALPHA-HELICAL ROPES

The interchain packing energy of two‐, three‐, and four‐stranded α‐helical ropes has been investigated. Poly‐L‐alanine was chosen as a model, and the interchain energies were calculated for various combinations of chain sense as a function of interchain distance, axial orientation and displacement. For comparison, the packing energies of the analogous assemblies of straight α‐helices were also computed. Only those systems in which the chains were equivalent, i.e., related by line symmetry, were considered. The results indicate that for structures in which all the chains are equivalent the interchain packing energy favors the coiled coil arrangements. Copyright © 1969 John Wiley & Sons, Inc.