  We investigate the folding behavior of protein sequences by numerically
studying all sequences with maximally compact lattice model through exhaustive
enumeration. We get the prion-like behavior of protein folding. Individual
proteins remaining stable in the isolated native state may change their
conformations when they aggregate. We observe the folding properties as the
interfacial interaction strength changes, and find that the strength must be
strong enough before the propagation of the most stable structures happens.
