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The Cumulative Effect of Surface Adsorption and Excluded Volume in 2D and 3D on Protein Fibrillation.

ABSTRACT: A refined mesoscopic model for the cumulative effect of repulsive excluded volume protein-protein interaction and attractive protein-surface interaction upon the properties of a trace protein capable of fiber formation is presented. The model predicts that very small changes in the magnitude of bulk volume occupancy or the strength of protein-surface attraction may result in very large changes in the extent of trace protein fibrillation and the distribution of trace protein between bulk and adsorbed phases.

SUBMITTER: Minton AP

PROVIDER: S-EPMC6838961 | biostudies-literature | 2019 Nov

REPOSITORIES: biostudies-literature

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The Cumulative Effect of Surface Adsorption and Excluded Volume in 2D and 3D on Protein Fibrillation.

Minton Allen P AP

Biophysical journal 20191001 9

A refined mesoscopic model for the cumulative effect of repulsive excluded volume protein-protein interaction and attractive protein-surface interaction upon the properties of a trace protein capable of fiber formation is presented. The model predicts that very small changes in the magnitude of bulk volume occupancy or the strength of protein-surface attraction may result in very large changes in the extent of trace protein fibrillation and the distribution of trace protein between bulk and adso ...[more]

PMID: 31629480

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Project description:Changes in excluded volume and contact interaction with the surface of a protein have been suggested as mechanisms for the changes in stability induced by cosolvents. The aim of the present paper is to present an analysis that combines both effects in a quantitative manner. The result is that both processes are present in both stabilizing and destabilizing interactions and neither can be ignored. Excluded volume was estimated using accessible surface area calculations of the kind introduced by Lee and Richards. The change in excluded volume on unfolding, deltaX, is quite large. For example, deltaX for ribonuclease is 6.7 L in urea and approximately 16 L in sucrose. The latter number is greater than the molar volume of the protein. Direct interaction with the protein is represented as the solvent exchange mechanism, which differs from ordinary association theory because of the weakness of the interaction and the high concentrations of cosolvents. The balance between the two effects and their contribution to overall stability are most simply presented as bar diagrams as in Fig. 3. Our finding for five proteins is that excluded volume contributes to the stabilization of the native structure and that contact interaction contributes to destabilization. This is true for five proteins and four cosolvents including both denaturants and osmolytes. Whether a substance stabilizes a protein or destabilizes it depends on the relative size of these two contributions. The constant for the cosolvent contact with the protein is remarkably uniform for four of the proteins, indicating a similarity of groups exposed during unfolding. One protein, staphylococcus nuclease, is anomalous in almost all respects. In general, the strength of the interaction with guanidinium is about twice that of urea, which is about twice that of trimethylamine-N-oxide and sucrose. Arguments are presented for the use of volume fractions in equilibrium equations and the ignoring of activity coefficients of the cosolvent. It is shown in the Appendix that both the excluded volume and the direct interaction can be extracted in a unified way from the McMillan-Mayer formula for the second virial coefficient.

Dataset Information

The Cumulative Effect of Surface Adsorption and Excluded Volume in 2D and 3D on Protein Fibrillation.

Publications

The Cumulative Effect of Surface Adsorption and Excluded Volume in 2D and 3D on Protein Fibrillation.

Similar Datasets

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