A Toy Model for Understanding the Conceptual Framework of Protein Folding: Rubik’s Magic Snake Model

There have been mainly three approaches to study the protein folding (PF) problem: One is the experimental determination of the PF. In this approach, submillisecond laser pulse spectroscopy experiments have revealed the nature of the relaxation process from unfolded to folded structures in the PF. The second is the so-called inverse PF problem. In this approach, it has been conjectured that the structures of the order of a thousand are realized in the real PF in Nature and the other structures are obtained by a combination of these structures. The third is the computer associated determination of the PF. There have recently appeared many theoretical investigations. In this approach, one mimics a protein as a selfavoiding linear chain of heteropolymer placed on a three(or two-) dimensional cubic (or square) lattice. Then, given an amino acid sequence with defining potential