Aggregated protein

Water-soluble polymers and polyelectrolytes (e.g., polyethylene glycol, polyethylene imine polyacrylic acid) have been used success-hilly in protein precipitations, and there has been some success in affinity precipitations wherein appropriate ligands attached to polymers can couple with the target proteins to enhance their aggregation. Protein precipitation can also be achieved using pH adjustment, since proteins generally exhibit their lowest solubility at their isoelectric point. Temperature variations at constant salt concentration allow for frac tional precipitation of proteins. 

Another important protein of the Clp family is ClpB which possesses ATPase activity. In a clpB mutation, 45% of the denatured and aggregated protein arising transiently after the transfer of an E. coli culture from 30 to 45 °C is stabilized [14]. ClpB seems to play an important role in the renaturation or proteolysis of the aggregated proteins, but the mechanism of action of ClpB is not yet known. One can suppose that it might participate in the resolubilization of aggregated proteins. 

They bind to predominantly hydrophobic regions of unfolded and aggregated proteins... 

Marushchak, D. and Johansson, L. B. (2005). On the quantitative treatment of donor-donor energy migration in regularly aggregated proteins. J. Fluoresc. 15, 797-803. 

Keywords Biomembrane DNA Fluorescent detection J-aggregate Protein... 

Cells have developed a sophisticated system of molecular chaperones and proteases to reduce the amount of unfolded or aggregated proteins (Wickner et al. 1999). Chaperones recognize hydrophobic stretches of polypeptides that become surface exposed as a consequence of misfolding or unfolding. If refolding attempts fail, irreversibly damaged polypeptides are removed by proteases. 

Polishing. This last process step prepares the product for final formulation or for actual sale. It is designed to remove any aggregated protein, remove residual chromatographic eluent(s), and place the product into a specific solvent. These requirements are admirably served by gel filtration. At this point, the sample volume is small and the product fraction to be applied is fairly clean. The gel and column equipment requirements are now within reason and, the clean samples result in much longer gel life. 

Phagocytosis Aggregated proteins and macromolecules with MW > 300kDa Does not play a role... 

Proteins can degrade via the physical processes of interfacial adsorption and aggregation. Proteins are surface-active molecules, i.e., they tend to adsorb at liquid solid, liquid air, and liquid-liquid interfaces. It is well established that proteins fold into their unique three-dimensional structures, which consist of a hydrophobic core... 

If preparative or instrumental artifact is ruled out, the universal occurrence of red-shifted Cotton effects with a-helical character in all the membranes studied points to a common property of the proteins in biological membranes. The ORD results from lipid-free mitochondrial structural protein and erythrocyte ghost protein are consistent with assigning the red shift in these membranes to aggregated protein. It is, therefore, reasonable that similar protein-protein association may occur in all membranes. Ionic requirements for membrane stability could then reflect in part the requirements for protein-protein association. To some extent the molecular associations which stabilize membranes, therefore, may be protein-protein as well as lipid-lipid in nature. 

Parker, T. G. and Dalgleish, D. G. 1977A. The use of light-scattering and turbidity measurements to study the kinetics of extensively aggregating protein as-Casein. Biopolymers 16, 2533-2547. 

Pool all the fractions contained within the main antibody peak, 1 e, corresponding to an Mr of 150,000 relative to protein standards. Discard any flanking fractions that may contain aggregated protein or contaminants of lower molecular weight... 

Lonsdale-Eccles, J. D., Teller, D. C., and Dale, B. A. (1982). Characterization of a phosphorylated form of the intermediate filament-aggregating protein filaggrin. Biochemistry 21, 5940-5948. 

Aggregation. Protein aggregation has two forms non-covalent (involving the interaction of two or more denatured proteins) and covalent (e.g., disulfide bond formation and/or peptide condensation reactions). 

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