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Protein precipitation is widely used in downstream processing of biological products in order to concentrate proteins and purify them from various contaminants. For example, in the biotechnology industry protein precipitation is used to eliminate contaminants commonly contained in blood. [1]
The net charge of the protein, determined by the sum charge of its constituents, results in electrophoretic migration in a physiologic electric field. These effects are short-range because of the high di-electric constant of water, however, once the protein is close to a charged surface, electrostatic coupling becomes the dominant force. [8]
The presence of multiple domains in proteins gives rise to a great deal of flexibility and mobility, leading to protein domain dynamics. [1] Domain motions can be inferred by comparing different structures of a protein (as in Database of Molecular Motions ), or they can be directly observed using spectra [ 12 ] [ 13 ] measured by neutron spin ...
However, because water is a polar molecule this process of simple diffusion is relatively slow, and in tissues with high water permeability the majority of water passes through aquaporin. [ 4 ] [ 5 ] The 2003 Nobel Prize in Chemistry was awarded jointly to Peter Agre for the discovery of aquaporins [ 6 ] and Roderick MacKinnon for his work on ...
The order of the tendency of ions to make or break water structure is the basis of the Hofmeister series. Hofmeister discovered a series of salts that have consistent effects on the solubility of proteins and, as it was discovered later, on the stability of their secondary and tertiary structures.
When a protein folds, the titratable amino acids in the protein are transferred from a solution-like environment to an environment determined by the 3-dimensional structure of the protein. For example, in an unfolded protein, an aspartic acid typically is in an environment which exposes the titratable side chain to water.
As of January 2013 less than 0.1% of protein structures determined were membrane proteins despite being 20–30% of the total proteome. [14] Due to this difficulty and the importance of this class of proteins methods of protein structure prediction based on hydropathy plots, the positive inside rule and other methods have been developed. [15 ...
Thermodynamically the flow of substances from one compartment to another can occur in the direction of a concentration or electrochemical gradient or against it. If the exchange of substances occurs in the direction of the gradient, that is, in the direction of decreasing potential, there is no requirement for an input of energy from outside the system; if, however, the transport is against ...