Hydrogen bonds hydrophobic interactions contrasted

In contrast with hydrogen bonding, hydrophobic interactions work in aqueous solutions. By choosing appropriate functional monomers, we can utilize these interactions for the preorganization in water. Cyclo-... 

Protein structure (and also the interactions between proteins and small molecules) is a compromise. It may be necessary to sacrifice a hydrogen bond or two in order to gain two or three hydrophobic interactions. In contrast, it may be necessary to place a hydrophobic residue in contact with water in order to pick up a few more hydrogen bonds in... 

The third class of host defense peptides, the extended peptide class, is defined by the relative absence of a defined secondary structure. These peptides normally contain high proportions of amino acids such as histidine, tryptophan, or proline and tend to adopt an overall extended conformation upon interaction with hydrophobic environments. Examples of peptides belonging to the extended class include indolicidin, a bovine neutrophil peptide, and the porcine peptide fragment, tritpticin. These structures are stabilized by hydrogen bonding and van der Waals forces as a result of contact with lipids in contrast to the intramolecular stabilization forces found in the former peptide classes. 

A reevaluation of molecular structure of humic substances based on data obtained primarily from nuclear magnetic resonance spectroscopy, X-ray absorption near-edge structure spectroscopy, electrospray ionization-mass spectrometry, and pyrolysis studies was presented by Sutton and Sposito (2005). The authors consider that humic substances are collections of diverse, relatively low molecular mass components forming dynamic associations stabilized by hydrophobic interactions and hydrogen bonds. These associations are capable of organizing into micellar structures in suitable aqueous environments. Humic components display contrasting molecular motional behavior and may be spatially segregated on a scale of nanometers. Within this new structural context, these components comprise any molecules... 

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