How Nature Disguises Chirality in Chiral Functional Nanostructures

Examination of protein 3-dimensional structures suggests that complex tertiary folds and quaternary associations can be deconstructed into a limited number of secondary structural elements, such as strands, helices, and turns, which are assembled using loosely structured loops. Those structures direct the sophisticated functions of proteins in living systems. Inspired by biological structures, chemists have worked to synthesize polymers with controlled helicity, not only to mimic the biological helices but also to realize their functions. The increasing amount of knowledge acquired from recent studies on elastomeric proteins has inspired the design and synthesis of biopolymers with interesting mechanical and biological properties. However, a lack of detailed understanding of the molecular folding mechanisms of these proteins limits the structure-based manipulation of related mechanical properties. We are interested in the synthesis, structure and function of hetero- and homo-chiral biopolymers able to assume specific ordered structures Elastomeric proteins are present in a wide range of biological systems, where they have evolved to meet specific functional needs. The ability of any protein to exhibit elasticity lies in its molecular and structural organization: individual components must be conformationally free so that they can respond quickly to the applied stress and they must form an inter-connected network of chains through covalent or no covalent crosslink, to effectively distribute the applied stress throughout the structure. The elastic properties of such proteins depend on the nature of elastomeric domains, the size of the domain and the degree of crosslinking. Here we present preliminary results on conformational behaviour of polymerizable subunits in which type II ?-turn act as spacer between hydrophobic segments having high propensity to form ?-helix. Reference 1. Tatham AS, Hayes L, Shewry PR, Urry DW. Biochim. Biophys. Acta, Protein Struct. Mol.Enzymol. 2001; 1548:187-193. 2. Lingin Li, Manoj B. Charati, Kristi L.Kiick, J. Polym. Chem. (2010) 1(8); 1160-1170 3. Urry D.W., Phil. Trans. R. Soc. Lond. B (2002) 357, 169-184 4. Navarro E., Fenude E., Celda B., Biopolymers (2002) 64, 198-209