Collapse and intramolecular phase layering in a polymer in which each unit may be in two states

The concept of a heteropolymer with mobile primary structure is discussed. It is used to examine the main aspects of the phenomenon of formation of globules by macromolecules capable of spiralization, adsorption of small molecules from solution, etc. The possibility of a kind of union of the cooperative trnsition of the helix-coil type and the comparatively smooth coil-globule transition is indicated. The unified transition is a phase transition of the first kind and is accompanied by sudden collapse of the polymer chain and sharp rearrangement of its linear structure. Intramolecular phase layering takes place directly at the point of the transition simultaneously affecting both the primary and tertiary structures.