Protein-surface interactions electrostatic interaction

Protein adsorption has been studied with a variety of techniques such as ellipsome-try [107,108], ESCA [109], surface forces measurements [102], total internal reflection fluorescence (TIRE) [103,110], electron microscopy [111], and electrokinetic measurement of latex particles [112,113] and capillaries [114], The TIRE technique has recently been adapted to observe surface diffusion [106] and orientation [IIS] in adsorbed layers. These experiments point toward the significant influence of the protein-surface interaction on the adsorption characteristics [105,108,110]. A very important interaction is due to the hydrophobic interaction between parts of the protein and polymeric surfaces [18], although often electrostatic interactions are also influential [ 116]. Protein desorption can be affected by altering the pH [117] or by the introduction of a complexing agent [118]. 

These reconstitution experiments supported the model for electron transfer shown in figure 14.8. In this model the complexes do not bind to each other directly. Instead, movement of electrons from complexes I and II to complex III is mediated by diffusion of UQH2 from one complex to the other within the phospholipid bilayer. Similarly, electrons move from complex III to complex IV by the diffusion of reduced cytochrome c along the surface of the membrane. Remember that cytochrome c differs from the other cytochromes in being a water-soluble protein. It is attached loosely to the membrane surface by electrostatic interactions. 

A second interfacially active component may also induce the surface activity of weakly surface-active proteins due to strong intermolecular interactions. Electrostatic interactions from anionic bile salts enhance the adsorption of cationic chitosan on emulsion droplets emulsified by using a mixture of phospholipids, cholesterol and such bile salts. Carrageenan interacts strongly with milk proteins, which is of importance in relation to the association to emulsions and to its application in stabilizing neutral dairy products. 

The interactions between protein molecules and solid surfaces can be classified into hydrophobic interactions, electrostatic interactions, hydrogen... 

Zhou et al (2003) developed a new residue-based protein-surface interaction potential model to explore the adsorption and orientation of two antibodies, IgGl and IgG2a. The Monte Carlo simulation results showed that when electrostatic interactions dominate, there are preferred... 

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