[Role of surface distribution of hydrophobic groups in the assembly of protein quaternary structure]

The method for two-dimensional representation of protein surfaces, based on the analogy with geographic map, and the algorithm for the search of the most favourable regions of izologous intermolecular interactions are proposed. It is assumed that the most favourable izologous interaction corresponds to an izologous contact of subunits which maximally dehydrates surface hydrophobic groups. The subunits are approximated by ellipsoids of revolution. The hydrophobic groups are assumed to be dehydrated if their C beta-atoms are inside the surface regions of the contacting ellipsoids inaccessible for contact with the sphere representing a water molecule. Using the proposed methods it is shown that for all izologous structures, known to atomic resolution, general shape of the molecule and distribution of hydrophobic groups on its surface: 1) provide a rough intersubunit recognition during assembly (deviation of the center of the experimentally localized contact region from the center of one of two-three regions obtained by us does not exceed 6--7 A); 2) choose only a few most favourable mutual orientations of the contacting regions; 3) can determine the pathway of the assembly.