Associations of macromolecules

Wolff C (1982) Non-Newtonian behaviour of associations of macromolecules in dilute solutions Adv Coll Interf Sci 17 263... 

Many supramolecular structures are formed largely by the stepwise noncovalent association of macromolecules, such as proteins. The processes of assembly are governed by the same chemical and physical principles that govern protein folding and the formation of quaternary structures (see Chap. 4). The driving force for the assembly process generally depends on the formation of a multitude of relatively weak hydrophobic, hydrogen and ionic bonds that occur between complementary sites on subunits which are in van der Waals contact with each other. In addition, covalent... 

In this section, we study the non-covalent association of macromolecules, say of proteins A and B to form a complex AB ... 

Phase diagram asymmetry can be evaluated by (i) the ratio of the biopolymer concentrations at a critical point, (ii) the angle made by the tie-lines with the concentration axis of one of the biopolymers and (iii) the length of the segment of a binodal curve between the critical point and the phase separation threshold. Association of macromolecules usually changes both their excluded volume and the affinity for the solvent water. This results in nonparallel tie-lines on the phase diagram. Normally, the tie-lines can be nonparallel since an increase in concentration of biopolymers is usually accompanied by their self-association. Equilibrium between the phases is not achievable when phase separation is accompanied by gelation. 

The studies of aggregation in polymer systems, association of macromolecules with other molecules, as well as of solubilization, are of extreme importance, since many processes that occur in living organisms (the formation of membranes and cellar structures, exchange processes, enzymatic catalysis, etc.) are all based on these phenomena. 

Such attractions may also exist between adjacent macromolecular skeins. Thus it is probable that at and around the viscosity minima associations of macromolecules exist. 

Further the coacervate is to be regarded as an association of macromolecules, in which the points of contact must not be thought of as static but dynamic, since it is still a typical liquid, though a viscous one. These conceptions, at which we have thus now arrived, stand diametrically opposed to the original ideas, in which it was still believed that the particles were permanently separated by a very considerable layer of hydration water. In the new ideas there is no longer any place for the view that the water present in the coacervate is bound as a whole by hydration forces. 

Wolff, C.7 Silberberg, A. Priel, Z. Layec-Raphalen, M.N. "Influence of the association of macromolecules in dilute solution on their reduced viscosity". Polymer, 20 (1979) 281-287... 

The purpose of this chapter is to review the principles of large zone size exclusion chromatography (large zone SEC) as applied to the study of self-association of macromolecules, specifically proteins. This selfassociation is not only of fundamental scientific interest, but also has practical consequences with respect to protein purification and to maintenance of biological function. The recent development of recombinant DNA technology has made available substantial amounts of sosie proteins, that were formerly available in very limited amounts if at all. These recombinant proteins must be obtained in a state that is fully biologically active. In some cases proteins are active as monomers, but in others the active protein exists as a dimer or an oligomer. Clearly it is of practical interest to understand the self-association of proteins under a variety of conditions. 

Hydrogen bonded complexes arise from the association of macromolecules containing electron deficient protons, typically polymeric carboxylic acids or alcohols, with polymers containing electron-donating groups such as ethers, pyrrolidones or alcohols [1,2,29-67]. The formation and stabilization of secondary polypeptide structure may be the result of hydrogen bonded complexation. 

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