Biomolecules supramolecular structures

Noncovalent interactions in metal complexes of biomolecules may play an important role in the creation of supramolecular structures around the metal center. For instance, extensive three-dimensional hydrogen-bonded stmcmres grow around metal complexes of barbiturates, recognized as the most widely used drugs for the treatment of epilepsy.Electrostatic interactions between a cation and the Trring of an aromatic molecule (cation-tt interactions) are common motifs in protein structures. Little is known about alkali and alkali-earth cation-tt inter-... 

This chapter has focused on the use of biomolecular supramolecular structures and biomolecule-nanoparticle (or carbon nanotubes) composites as functional units for the construction of electrical devices. 

Supramolecular structures include aggregates of biomolecules held together by noncovalent bonds. These enable many functions that are key to terran life and are presumed to be key to life generally. 

Terran life uses water as a solvent. As expected, terran biomolecules have multiple signatures of their compatibility with water as a solvent. Further, terran biochemistry exploits the distinction between polar molecules, which are soluble in water, and nonpolar molecules, which are not. This is exemplified in the use of hydrophobic interactions as a way to fold proteins and organize supramolecular structures, inter alia. 

Nuclear magnetic resonance spectroscopy can be applied to the study of biomolecules for structural and conformational elucidation, the modes of interaction between and within molecules, and the dynamics in supramolecular complexes. 

Water behaves differently in different environments. Properties of water in heterogenous systems such as living cells or food remain a field of debate. Water molecules may interact with macromolecular components and supramolecular structures of biological systems through hydrogen bonds and electrostatic interactions. Solvation of biomolecules such as lipids, proteins, nucleic acids, or saccharides resulting from these interactions determines their molecular structure and function. 

In living organisms the molecules in supramolecular structures assemble spontaneously. Biomolecules are able to self-assemble because of the steric information they contain. 

The information that permits the self-assembly of biomolecules consists of the complementary shapes and distributions of charges and hydrophobic groups in the interacting molecules. Large numbers of weak interactions are required for supramolecular structures to form. In this diagrammatic illustration, several weak noncovalent interactions stabilize the binding of two molecules that possess complementary shapes. 

Pressures used to investigate biochemical systems range from 0.1 MPa to about 1 GPa (0.1 MPa = 1 bar, 1 GPa = 10 kbar). Such pressures only change intermolecular distances and affect conformations, but do not change covalent bond distances or bond angles. In fact, pressures in excess of 30 kbar are required to change the electronic structure of a molecule. The covalent structure of low molecular mass biomolecules (peptides, lipids, saccharides), as well as the primary structure of macromolecules (proteins, nucleic acids and polysaccharides), is not perturbed by pressures up to about 20 kbar. Pressure acts predominantly on the conformation and supramolecular structures of biomolecular systems. 

Water can be regarded as the most important substance for life oti Earth. It is the most widely used solvent of biomolecules. However, it is also a very complicated solvent. With H-bonding donor and acceptor sites, this polar solvent strongly influences the properties of solutes. It is interesting that water forms supramolecular structures with many kinds of macromolecules, including DNA, proteins, and many synthetic polymers [26, 29, 32, 41, 57, 58]. Several typical water-macromolecule assemblies have been investigated by SMFS. 

The dramatic development of bioehemistry in the twentieth century can largely be attributed to breakthroughs in the understanding of the supramolecular structure of biomolecules. Pauling and Corey s work on the structure of proteins and the discovery of the DNA double helix demonstrated the critical importance of supramolecular structure in biology and stimulated interest in its study as well as in the processes by which it is formed. 

Due to the prevalence of vicinal diol and aminoalcohol functionalities in biomolecules, the gauche effect is likely to contribute to a variety of biochemical properties and phenomena. Stability of supramolecular structures formed by fats and hpids depends on the energy cost (or lack thereof) of projecting multiple OR groups to the desired direction. 

Advanced synchrotron based characterization techniques of solid state applied to macromolecules are reported in Chapter 4. After an introduction to the physics and principles of NEXAFS and XPS spectroscopy, the main features of these techniques that allow a non conventional assessment of the electronic and chemical structure are depicted. The study of macromolecular organization and self-assembly can be nicely obtained by these spectroscopic tools. For example the formation of SAMs (Self Assembled Monolayers) of a variety of molecules arranged in supramolecular assemblies can be detected as well as the behaviour of biomolecules bound to surfaces mimicking biological substrates. Many examples of macromolecules studied with NEXAFS and XPS highlight the potential of these spectroscopic methods to give insight into the molecular and supramolecular structure which in turn determine the most desired properties. 

Molecule.s Are die Units for Building Complex Structures Properdes of Biomolecules Reflect Their Fitne.ss to die Living Condition Organizadon and Structure of Cells Viru.ses Are Supramolecular As.semblies Acting as Cell Parasites... 

The tremendous progress in supramolecular chemistry and nanoscience provided intellectual concepts and guidelines to implement biomolecules and nano-objects as functional units for the self-assembly of biomolecular structures, or biomolecule-nanoparticle hybrid systems. Such biomolecular supramolecular complexes or hybrid biomolecular composites are anticipated to reveal properties and functions that emerge from the complexity of the structures. 

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