Biological systems entropic ordering

One of the earliest decisions was to calibrate the GRID force field whenever possible by using experimental measurements rather than theoretical computations, and calorimetric measurements were therefore needed for the initial calibration in order to differentiate the enthalpic and entropic contributions to the overall free energy. However, only a very little calorimetric data was readily available at that time, about well characterised biological systems in which the structures of the interacting ligand and macromolecule were both known, and so a different approach was initially needed. 

There is increasing evidence that entropic ordering is important in many biological systems. For example, this phenomenon seems to be responsible for the clumping of sickle-cell hemoglobin in the presence of much smaller proteins that act as the smaller balls. Entropic forces also have been linked to the clustering of DNA in cells without nuclei, and Allen Minton of the National Institutes of... 

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