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United States Department of Agriculture

Agricultural Research Service

Title: Investigation of Hydrophobic Surface Interactions in Colloidal and Biological Systems by Molecular Dynamics Simulations and Nmr Spectroscopy

Authors
item Alaimo, Michael
item Kumosinski, Thomas

Submitted to: Langmuir
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 27, 1997
Publication Date: N/A

Interpretive Summary: A new parameter which quantitates the sticky property of detergent molecules when they are placed in water, was added to the molecular modeling computer software. The measurement of the sticky nature of other types of molecules is useful to the scientific community. In food science these molecular interactions are important in determining food properties like texture, taste and appearance. The new molecular modeling evaluations were demonstrated to be essential in quantitating sticky properties in forming many kinds of foods like cheese and salad dressings. Experimental data were used to support the conclusions drawn from modeling results, which will help food technologists to understand the diverse functional properties of foods.

Technical Abstract: Interactions of hydrophobic molecular domains determine many of the functional properties of food proteins and colloidal food aggregates, such as emulsification, gelation and foaming ability. A molecular basis for macromolecular interactions and conformational stability is established through investigation of simple model systems. Molecular modeling and dynamics simulations have been used to study the role of hydrophobic interaction forces in driving the formation of model amphiphile aggregates systems. An approximation to hydrophobic attraction between hydrocarbon tails was required to achieve stable, dynamic aggregate models for Aerosol- OT (AOT)/water/oil microemulsions, micelles of AOT in water and for a stacked AOT/para -chlorophenol gel in either CCl4 or benzene. One- and two dimensional NMR spectroscopic methods have been used to characterize the pH and temperature dependent conformational changes in the model polypeptide poly(L-lysine). Changes in proton chemical shifts and linewidths indicate that the backbone mobility of poly(L-lysine) is not greatly diminished by the coil-helix transition. ROESY and Transverse-ROESY couplings, as well a T1 and T2 relaxation measurements, suggest that lysyl sidechain mobility remains largely unrestricted upon formation of periodic secondary structure Molecular dynamics simulations of poly(L-lysine) conformers substantiate th importance of hydrophobic sidechain domains in stabilizing secondary structural features in aqueous solution.

Last Modified: 8/22/2014
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