Qualitative analysis is presented for a system of differential equations, which play an important role in a theory of molecular self-organization:.i= r,lkit, xp kt,,xox, i=l Besides the general case two simplifications are treated:(1) the norihyperbolic case: k 0. _->0 (k, 0) and(2) cyclic symmetry: kii ki+l,j+l.Criteria for cooperation and exclusion are derived.