Shear-induced Conformational Changes and Gelation of Soy Protein Isolate Suspensions

Ker, Yi-Chang; Chen, R.H.

doi:10.1006/fstl.1997.0306

Cited by 12 publications

(16 citation statements)

References 17 publications

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“…When comparing the intracellular and extracellular environments, some stresses that can contribute to protein unfolding are greater in the latter. This includes hydrodynamic shear stress resulting from the hydraulic force of plasma being pumped around the body (30,31); normal arterial shear stress is between 10 and 70 dynes/cm 2 (32). The extracellular environment is also more oxidizing than the cytosol (33).…”

Section: Discussionmentioning

confidence: 99%

Identification of Human Plasma Proteins as Major Clients for the Extracellular Chaperone Clusterin

Wyatt¹,

Wilson

2010

Journal of Biological Chemistry

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Clusterin (CLU) is an extracellular chaperone that is likely to play an important role in protein folding quality control. This study identified three deposition disease-associated proteins as major plasma clients for clusterin by studying CLU-client complexes formed in response to physiologically relevant stress (shear stress, ϳ36 dynes/cm 2 at 37°C). Analysis of plasma samples by size exclusion chromatography indicated that (i) relative to control plasma, stressed plasma contained proportionally more soluble protein species of high molecular weight, and (ii) high molecular weight species were far more abundant when proteins purified by anti-CLU immunoaffinity chromatography from stressed plasma were compared with those purified from control plasma. SDS-PAGE and Western blot analyses indicated that a variety of proteins co-purified with CLU from both stressed and control plasma; however, several proteins were uniquely present or much more abundant when plasma was stressed. These proteins were identified by mass spectrometry as ceruloplasmin, fibrinogen, and albumin. Immunodot blot analysis of size exclusion chromatography fractionated plasma suggested that CLU-client complexes generated in situ are very large and may reach >4 ؋ 10 7 Da. Lastly, sandwich enzymelinked immunosorbent assay detected complexes containing CLU and ceruloplasmin, fibrinogen, or albumin in stressed but not control plasma. We have previously proposed that CLUclient complexes serve as vehicles to dispose of damaged misfolded extracellular proteins in vivo via receptor-mediated endocytosis. A better understanding of these mechanisms is likely to ultimately lead to the identification of new therapies for extracellular protein deposition disorders.

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Section: Discussionmentioning

confidence: 99%

Identification of Human Plasma Proteins as Major Clients for the Extracellular Chaperone Clusterin

Wyatt¹,

Wilson

2010

Journal of Biological Chemistry

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“…Physiological factors such as macromolecular crowding and shear stress are likely to favor protein aggregation in vivo compared with low concentrations of purified proteins in simple buffers (2,29,30). Thus, like many other studies of chaperone action, we used elevated temperature to induce client proteins to unfold and interact with CLU in vitro.…”

Section: Discussionmentioning

confidence: 99%

“…Uncontrolled unfolding and the consequent accumulation of insoluble protein aggregates is implicated in the pathology of many diseases including Alzheimer disease and type II diabetes and is promoted by various stresses such as oxidative stress (1), shear stress (2), and thermal stress (3). Cells have extensive quality control mechanisms to ensure that intracellular proteins are maintained predominantly in their native conformations.…”

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confidence: 99%

Structural Characterization of Clusterin-Chaperone Client Protein Complexes

Wyatt

Yerbury

Wilson

2009

Journal of Biological Chemistry

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Clusterin (CLU) is a potent extracellular chaperone that inhibits protein aggregation and precipitation otherwise caused by physical or chemical stresses (e.g. heat, reduction). This action involves CLU forming soluble high molecular weight (HMW) complexes with the client protein. Other than their unquantified large size, the physical characteristics of these complexes were previously unknown. In this study, HMW CLUcitrate synthase (CS), HMW CLU-fibrinogen (FGN), and HMW CLU-glutathione S-transferase (GST) complexes were generated in vitro, and their structures studied using size exclusion chromatography (SEC), ELISA, SDS-PAGE, dynamic light scattering (DLS), bisANS fluorescence, and circular dichroism spectrophotometry (CD). Densitometry of Coomassie Blue-stained SDS-PAGE gels indicated that all three HMW CLU-client protein complexes had an approximate mass ratio of 1:2 (CLU:client protein). SEC indicated that all three clients formed complexes with CLU > 4 ؋ 10 7 Da; however, DLS estimated HMW CLU-FGN to have a diameter of 108.57 ؎ 18.09 nm, while HMW CLU-CS and HMW CLU-GST were smaller with estimated diameters of 51.06 ؎ 6.87 nm and 52.61 ؎ 7.71 nm, respectively. Measurements of bisANS fluorescence suggest that the chaperone action of CLU involves preventing the exposure to aqueous solvent of hydrophobic regions that are normally exposed by the client protein during heat-induced unfolding. CD analysis indicated that, depending on the individual client protein, CLU may interact with a variety of intermediates on protein unfolding pathways with different amounts of native secondary structure. In vivo, soluble complexes like those studied here are likely to serve as vehicles to dispose of otherwise dangerous aggregationprone misfolded extracellular proteins.Controlled unfolding is important in many biological processes including protein translocation, degradation by proteases, and regulation of enzyme activity. Uncontrolled unfolding and the consequent accumulation of insoluble protein aggregates is implicated in the pathology of many diseases including Alzheimer disease and type II diabetes and is promoted by various stresses such as oxidative stress (1), shear stress (2), and thermal stress (3). Cells have extensive quality control mechanisms to ensure that intracellular proteins are maintained predominantly in their native conformations. Molecular chaperones are known to play a central role in these systems by targeting unfolded proteins for refolding or degradation (4 -7). However, little is known about the existence of corresponding systems for protein folding quality control in the extracellular environment (8).A large number of alternative functions have been proposed for clusterin (CLU), 4 nevertheless, the potent chaperone activity of this protein (9 -13) and its constitutive presence in many biological fluids suggests that it is likely to be important in extracellular protein folding quality control. Recently haptoglobin (14) and ␣ 2 -macroglobulin (15, 16) have also been identified as extracellular ch...

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“…The effects of shear on conformation and properties of different globular protein have been extensively investigated. At low pH, the protein is highly charged and the application of shear stress promotes the formation of fibrillar structure in globular proteins such as whey protein isolate (Akkermans et al ., ), Bovine serum albumin (Bekard et al ., ), lysozyme (Ow & Dunstan, ), β‐lactoglobulin (Akkermans et al ., ; Hill et al ., ; Dunstan et al ., ), amyloid‐β (Hamilton‐Brown et al ., ; Dunstan et al ., ) and soy proteins (Ker & Chen, ; Akkermans et al ., ).…”

Section: Introductionmentioning

confidence: 99%

The effect of shear on the rheology and structure of heat‐induced whey protein gels

Badii

Atri

Dunstan

2016

Int J of Food Sci Tech

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The influence of mechanical shearing on the small deformation properties and microstructure of heat-induced whey protein gel has been studied. The viscoelastic properties of these gels at different concentrations of 10% and 20% (w/w) exposed to different shear rates of 0, 50, 100, 200 and 500 s À1 during gelation were measured using dynamic oscillatory rheometry. The structure of both the shear treated and unsheared gels was then investigated using light microscopy. The results showed that the storage modulus of the gels at both concentrations was increased by increasing the shear rate exposure during gelation while the shear-treated gels were more elastic and showed frequency-independent behaviour. As the total protein concentration of the gel increased, the viscoelastic properties of the gels also increased significantly and the gels showed greater elasticity. The gels obtained from the higher shear rate exposure were stronger with higher elastic moduli at both protein concentrations. Images of the gels obtained using light microscopy showed that shearing resulted in phase separation and some aggregation in the structure of the gels at both concentrations. However, the shearing rates applied in this study were not enough to cause aggregation breakdown in the gel network.

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Shear-induced Conformational Changes and Gelation of Soy Protein Isolate Suspensions

Cited by 12 publications

References 17 publications

Identification of Human Plasma Proteins as Major Clients for the Extracellular Chaperone Clusterin

Identification of Human Plasma Proteins as Major Clients for the Extracellular Chaperone Clusterin

Structural Characterization of Clusterin-Chaperone Client Protein Complexes

The effect of shear on the rheology and structure of heat‐induced whey protein gels

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