Calorimetric Observations of Protein Conformation at Solid—Liquid Interfaces

Yan, Guoying; Li, J.-T.; Huang, Steve; Caldwell, Karin D.

doi:10.1021/bk-1995-0602.ch018

Cited by 12 publications

(5 citation statements)

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“…Feng and Andrade (32) have shown that several proteins adsorbed to pyrolytic carbon no longer show any release of heat at the expected transition temperatures, suggesting that pyrolytic carbon induces complete unfolding, which is consistent with the tenacious binding of proteins to this surface. However, Yan et al (24) have shown that albumin and lysozyme adsorbed to polystyrene exhibit no unfolding enthalpy, while streptavidin adsorbed to polystyrene displays an unfolding enthalpy that is very similar to that for the native protein in solution. All these results indicate that changes in the enthalpy of unfolding depend on the adsorbing surface and the protein.…”

Section: Resultsmentioning

confidence: 99%

Conformational Changes of Fibrinogen Adsorption onto Hydroxyapatite and Titanium Oxide Nanoparticles

Chen

Zhang

Gong

et al. 1999

Journal of Colloid and Interface Science

120

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Section: Resultsmentioning

confidence: 99%

Conformational Changes of Fibrinogen Adsorption onto Hydroxyapatite and Titanium Oxide Nanoparticles

Chen

Zhang

Gong

et al. 1999

Journal of Colloid and Interface Science

120

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“…It is possible that DSC measurements on finely dispersed systems of high surface-to-volume ratio could provide such information. 36…”

Section: Discussionmentioning

confidence: 99%

“…Additional support for this mechanism could come from knowledge of the hydration of PEO attached to surfaces. It is possible that DSC measurements on finely dispersed systems of high surface-to-volume ratio could provide such information …”

Section: Discussionmentioning

confidence: 99%

Protein Resistance of Surfaces Prepared by Sorption of End-Thiolated Poly(ethylene glycol) to Gold: Effect of Surface Chain Density

2005

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Nonspecific protein adsorption generally occurs at the biomaterial-tissue interface and usually has adverse consequences. Thus, surfaces that are protein-resistant are eagerly sought with the expectation that these materials will exhibit improved biocompatibility. Surfaces modified with end-tethered poly(ethylene oxide) (PEO) have been shown to be protein-resistant to some degree. Although the mechanisms are unclear, it has been suggested that chain length, chain density, and chain conformation are important factors. To investigate the effects of PEO chain density, we selected a model system based on the chemisorption of chain-end thiolated PEO to a gold substrate. Chain density was varied by varying PEO solubility (proximity to cloud point) and incubation time in the chemisorption solution. The adsorption of fibrinogen and lysozyme to these surfaces was investigated. It was found that for 750 and 2000 MW PEO layers, resistance to fibrinogen increased with chain density and was maximal at a density of approximately 0.5 chains/nm(2) (80% decrease in adsorption compared to unmodified gold). As PEO chain density increased beyond 0.5/nm(2) adsorption increased. For PEO of 5000 MW the optimal chain density was 0.27/nm(2) and gave only a 60% reduction in fibrinogen adsorption. It is suggested that, at high chain density, the chemisorbed PEO is dehydrated giving a surface that is no longer protein resistant. The PEO-modified surfaces were found also to be resistant to lysozyme adsorption with reductions similar to, if somewhat less than, those for fibrinogen. The fibrinogen to lysozyme molar ratios were within the expected range for close-packed layers of these proteins in their native conformation and were relatively insensitive to PEO chain density and MW. This may suggest that such adsorption as did occur, even at chain densities giving minimum adsorption, may have been on patches of unmodified gold.

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“…There is now some experimental evidence that "compact" globular proteins maintain their native structure when adsorbed and that only some "soft/flexible" proteins suffer some degree of denaturation upon adsorption, especially on hydrophobic surfaces. 7 The second step, therefore, involves primarily an orientation process that is thermodynamically driven and yields proteins in the most energetically favorable orientation. Independent evidence of protein orientation at interfaces has been obtained by Lee and Saavedra.…”

Section: Introductionmentioning

confidence: 99%

Imaging the Molecular Dimensions and Oligomerization of Proteins at Liquid/Solid Interfaces

et al. 1998

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Individual Concanavalin A (ConA) molecules have been imaged at the liquid/solid interface with an atomic force microscope (AFM). Three-dimensional sizing with very high resolution (<5 Å) has been obtained by a novel approach based on height distributions, which avoids the tip convolution effects which normally affect scanning probe microscopy techniques. Each height measurement correlates to a particular molecular orientation on the surface. A large number of such measurements provide a statistical ensemble of orientations. The complete height distribution reflects the three-dimensional size of the protein sample and hence its tertiary and quaternary structure. A surface adsorption and orientation model, based on a minimization of surface adsorption energy, is proposed. This model is in good agreement with the observed height distribution of Con A molecules at the liquid/solid interface. Analysis of Con A and succinylated Con A molecules on mica demonstrates that Con A dimers are the prevalent species at the liquid/solid interface. This is in contrast to the tetrameric organization of Con A normally observed in solution. The new possibilities opened by height distribution analysis on the physical characterization of biomolecules at interfaces are also discussed.

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Calorimetric Observations of Protein Conformation at Solid—Liquid Interfaces

Cited by 12 publications

References 0 publications

Conformational Changes of Fibrinogen Adsorption onto Hydroxyapatite and Titanium Oxide Nanoparticles

Conformational Changes of Fibrinogen Adsorption onto Hydroxyapatite and Titanium Oxide Nanoparticles

Protein Resistance of Surfaces Prepared by Sorption of End-Thiolated Poly(ethylene glycol) to Gold: Effect of Surface Chain Density

Imaging the Molecular Dimensions and Oligomerization of Proteins at Liquid/Solid Interfaces

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