Protein crystallization electrolyte effects

Salting-out is not well understood. One popular explanation for this effect relies on the relative hydration of the protein versus bulk electrolyte. In this model, the electrolyte is assumed to bind bulk water as water of hydration near the ion s surface. Likewise, the protein needs to be hydrated with water. As the bulk electrolyte and the protein compete for bulk water to hydrate their respective surfaces, the protein become partially dehydrated and prefers to fill such exposed surface (dehydrated surface) with other protein molecules thus, facilitating crystal contacts. Thus, the solubility of the protein is reduced as the electrolyte is added to the protein solution. The effectiveness of ions (cations and anions) to cause phase separation (or lower solubility) has been documented by... 

Ice formation is both beneficial and detrimental. Benefits, which include the strengthening of food stmctures and the removal of free moisture, are often outweighed by deleterious effects that ice crystal formation may have on plant cell walls in fmits and vegetable products preserved by freezing. Ice crystal formation can result in partial dehydration of the tissue surrounding the ice crystal and the freeze concentration of potential reactants. Ice crystals mechanically dismpt cell stmctures and increase the concentration of cell electrolytes which can result in the chemical denaturation of proteins. Other quaHty losses can also occur (12). 

Popular approaches to molecular self-assembly, which can give structures in the nanometer to millimeter range, are based on SAMs and LBL deposition of electrolytes. Self-assembly leads to equilibrium structures that are close to the thermodynamic minimum and result from multiple weak, reversible interactious betweeu subuuits which include hydrogen bonds, ionic bonds, and van der Waals forces. As information is already coded in the building blocks, this is a means to avoid defect formation in aggregate formation. SAMs are molecular assemblies of long chain alkanes that chemisorb on the patterned and unpat-temed surfaces of appropriate solid materials. The structures of SAMs, effectively 2D-crystals with controllable chemical functionality, make them a means to modify substrates to direct protein adsorption and cell attachment, surface passivation, ultrathin resists and masks and sensor development. 

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