Aggregation peptides/proteins

Perutz, M. F., Pope, B. J., Owen, D., Wanker, E. E., and Scherzinger, E. (2002b). Aggregation of proteins with expanded glutamine and alanine repeats of the glutamine-rich and asparagine-rich domains of Sup35 and of the amyloid /1-peptide of amyloid plaques. Proc. Natl. Acad. Sci. USA 99, 5596-5600. 

In peptide/protein pharmaceuticals, the GAS process is predominantly applied for the preparation of microparticulate protein powders as an alternative to common drying processes. However, Winters et al. [69] reported an increase of P-sheet aggregates during the precipitation of lysozyme, trypsin, and insulin as a consequence of stress parameters such as organic solvent, pressure, and shear forces. One reason... 

Following successful recovery of peptide/protein molecule from the microspheres, a simple spectrophotometric method does not always allow discrimination between the monomeric protein form and its aggregates. However, HPLC might separate these species and thus provides more accurate qualitative data [96], But HPLC cannot quantify exclusively the amount of active protein antigen, as is the case with ELISA techniques [97], Nowadays, Fourier transform infrared (FTIR) spectroscopy has become a popular, noninvasive method, as it is able to characterize the secondary structure of entrapped proteins [26, 95, 98-101], Only recently, the integrity of their primary structure was evaluated, thanks to a new matrix-assisted laser... 

Prevention/Minimization of Moisture-Induced Instability Moisture- and microclimate acid pH-induced instability (typically the aggregation) of the peptide/protein... 

One of the best studied proteins is the amyloid peptide, which seems capable of inducing free radical production in Alzheimer disease [69]. Amyloid peptide can bind metals and these can produce radicals through the Fenton reaction [70,71]. Since aggregation of proteins is also promoted through metals, a spiral of aggregation steps starts... 

Valincius et al. used NR and ex situ electrochemical impedance spectroscopy to study the effect of amyloid (J-pephde insertion on supported hpid bilayers [60]. It has been speculated that the interaction between these oligomeric proteins and bilayer membranes plays an important role in the aggregation and protein misfold-ing that leads to various neurodegenerahve diseases including Alzehimer s and Parkinson s diseases [61]. Using a variety of solvent and phospholipid contrasts, including the use of perdeuterated phosphohpids, NR demonstrated that amyloid P-peptides inserted into hpid bilayers tethered to a gold-modified silicon substrate. 

Recognition (or aggregation) between proteins/peptides and the protein folding process may be viewed as two facets of the same problem. Whether the contacts are... 

Proteins are particularly susceptible to modification and degradation through a variety of pathways, leading to the formation of several types of variants. Some of the more commonly encountered pathways include deamidation, oxidation, dimerization/aggregation, peptide bond cleavage through proteolysis or hydrolysis, N- or C-terminal... 

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