Biological systems hydrogen bonding

The work which is reviewed here provides accurate structural data from micro-wave and radiofrequency spectroscopy of relatively small molecule, hydrogen bonded complexes. Its role has been to provide information concerning the stereochemistry and electronic properties — electric dipole moments and nuclear hyperfine interactions — characteristic of hydrogen bonds. The experiments are done on gas phase samples, often in molecular beams, which eliminates environmental perturbations of the hydrogen bonds. In addition, the small molecules used are amenable to ab initio calculations 7 9) and thus the results are extremely useful as criteria for the accuracy of these calculations. Finally, the results are useful to construct models of more complex systems in chemistry and biology involving hydrogen bonds 4). 

Four main types of noncovalent Interactions occur In biological systems Ionic bonds, hydrogen bonds, van der Waals Interactions, and Interactions due to the hydrophobic effect. 

Hydrogen bonds play an important part in determining such properties as solubility, melting points, and boiling points, and in affecting the form and stability of crystal structures. They play a crucial role in biological systems. For ex-... 

It is well estabhshed that sulfur compounds as well as elemental sulfur have the tendency to form long chain molecules. All of these substances can be regarded as derivatives of the hydrogen polysulfanes (or polysulfanes) H2S . Polysulfanes form a long series of homologous chain-like molecules since the number n can assume any value. S-S and S-H bonds are frequently found in chemical and biological systems. Thus, polysulfanes have been the subject of numerous experimental and theoretical studies (for a recent review, see [15]). 

In a real biological system, DNA is mostly surrounded by many proteins. Protein binding to DNA involves a number of hydrogen bonds and electrostatic contacts between two biopolymers, and induces not only structural deviation from the typical B-form structure, but also electronic perturbation of the -stacked array of base pairs. We tackled the electronic effects of protein binding on the efficiency of hole transport by using a restriction en-... 

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