Proteins aggregate formation

Hydrophobic interaction chromatograph (HIC), while very attractive in principle, has proved difficult to scale up for processing. A recent series of articles explores some of the unique problems associated with process-scale HIC. Load sample preparation20 must be carefully examined to prevent protein aggregate formation in the presence of the relatively high salt concentrations used in this technique. Successful scale-up also requires the setting of wide specifications to accomodate routine variations in the feed.21 The effect of the salt concentration on capacity may be somewhat more... 

The problem of in vitro protein folding has become a major barrier to the successful use of bacterial systems for protein production. Bacterial hosts often produce inactive protein in the form of inclusion bodies. The refolding of this inactive protein results in the recovery of the native molecules as well as misfolded and aggregated proteins. Aggregate formation reduces the yield of... 

Fig. 7 Enzyme activity, proteasomal degradation, and protein aggregate formation are de-...

Figure 7.3 Characteristics of stationary phases used for gel filtration and GPC columns. (a) Graphs indicating the mass ranges for two phases in gel filtration and for three phases in gel permeation (b) Calibration curves (logM = /(V)) for these different phases obtained with proteins for gel filtration and with polystyrene standards for the others (known molecular weights). A weak slope from the linear section reveals a better resolution between neighbouring masses. This is the case when the pores are of regular dimension. The curves logM = f[K), more rarely studied, reveal the same aspect (reproduced courtesy of Tosohaas and Polymer Lab.). To avoid protein aggregate formation, denaturing compounds are sometimes introduced to the aqueous mobile phase.

P Amyloid protein aggregation, leading to formation of plaques / Hyperphosphorylation of tau protein, leading to intracellular NFT development and collapse of microtubules / Inflammatory processes—levels of multiple cytokines and chemokines are elevated in AD brains / Neurovasculature dysfunction / Oxidative stress / Mitochondrial dysfunction... 

Fig. 3. Solubility of silk proteins in solution as a function of time. Low solubility corresponds to protein aggregation. The fast and slow aggregations are observed in vitro (Dicko et al., 2004a), whereas the stable helical conformation (storage structure) is observed in vivo (Dicko et al., 2004b,d). This illustrates the inherent instability of silk protein in solution and shows the /(-sheet polymorph structure as the most stable form. In other words, the spiders actively control and modulate the unavoidable silk protein aggregation prior to fiber formation.

Proteins in their native form are the globules, the structures of which (the so called tertiary structure) strongly differ for different proteins. At the same time, on the level of secondary structure only three major forms are realized, namely a-helix, p-sheet, and random coil. As the two first mentioned forms are periodical, they could possibly serve as the templates for the J-aggregate formation. Nevertheless, there are only a few reports about the dye aggregates formed on proteins. 

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