Protein supermolecular assemblies

J. C. Sacchettini, L. G. Baum, and C. F. Brewer, Multivalent protein-carbohydrate interactions. A new paradigm for supermolecular assembly and signal transduction, Biochemistry, 40 (2001) 3009-3015. 

The study of the interaction between two complementary macromolecules and the aggregation of the resulting complexes to a supermolecular structure in solution is of special interest, because many biological phenomena such as enzymatic processes, supermolecular assemblies in virus shells, and muscle contraction depend on specific protein-protein interactions. Studies on synthetic macromolecules may serve as models of such phenomena. 

Abstract The optical achvities of poly-(R)-lactide, poly-(S)-lactide, poly(beta -hydroxybutyrate) and two beta -hydroxyvalerate copolymers were measured in soluhon, as solid powders in suspension, and where possible, as films. Poly-(plus)-3-methyl-I-pentene was also reinvestigated. In some cases the specific rotahon values of powder samples showed significant differences from the values of the solution measurements. The discrepancies of the data observed seem to reflect the local environment of the polymer chains in supermolecular assemblies and consequently the sohd state structure (morphology) of the polymers. The circular dichroism (CD) spectra of the polymers were also measured in solution and in the form of their films. For comparison, the CD spectra of the namrally occurring protein casein and of the synthetic polypeptide poly-(i-)-proline were also measured. (Author abstract) 2 I Refs. 

Protein is an excellent natural nanomaterial for molecular machines. Protein-based molecular machines, often driven by an energy source such as ATP, are abundant in biology. Surfactant peptide molecules undergo self-assembly in solution to form a variety of supermolecular structures at the nanoscale such as micelles, vesicles, unilamellar membranes, and tubules (Maslov and Sneppen, 2002). These assemblies can be engineered to perform a broad spectrum of functions, including delivery systems for therapeutics and templates for nanoscale wires in the case of tubules, and to create and manipulate different structures from the same peptide for many different nanomaterials and nanoengineering applications. 

In contrast to supermolecular materials, a supramolecular system is a self-assembled, noncovalently bonded entity, in which molecular units are assembled through noncovalent forces to create a complex structureFor large entities, such supramolecular systems are similar in constitution to those of quaternary structures found in proteins. Thus, for a supramolecular system, it is possible to have variations in the constitution depending on how many molecular units are present and the nature of the bonding interactions. The subunits in the case of supramolecular systems need not be mesomorphic as long as the assembled entity is. 

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