Interhelical contacts determining the architecture of alpha-helical globular proteins.

An approach based on a presentation of alpha-helical protein topology as a graph is presented. The approach allows to estimate a role of each interhelical contact in the whole protein topology and to classify the contacts. It is shown that a consideration of only about a half of the whole pool of interhelical contacts exposed in the protein is enough for a determination of protein architecture. Such contacts are called as major and their quantitative characteristics are obtained. Moreover, providing a clear and simple presentation of the protein topology, the approach can be applied for a description of structural domain/subdomain arrangement of alpha-helical proteins and illustration of their folding/denaturation paths.