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Effects of disulfide bridges and backbone connectivity on water sorption by protein matrices

Effects of disulfide bridges and backbone connectivity on water sorption by protein matrices

Authors :
Sang Beom Kim
Rakesh S. Singh
Prem K. C. Paul
Pablo G. Debenedetti
Source :
Scientific Reports, Vol 7, Iss 1, Pp 1-9 (2017)
Publication Year :
2017
Publisher :
Nature Portfolio, 2017.

Abstract

Abstract Understanding the water sorption behavior of protein powders is important in applications such as the preservation of protein-based pharmaceuticals. Most globular proteins exhibit a characteristic sigmoidal water adsorption isotherm at ambient conditions. However, it is not well understood how water sorption behavior is influenced by intrinsic factors that are related to structural properties of proteins. We investigate computationally how structural constraints on proteins influence the water sorption isotherms of amorphous protein powders. Specifically, we study the effects of non-local disulfide linkages and backbone connectivity using pheromone ER-23 and lysozyme as model proteins. We find that non-local disulfide linkages can significantly restrict structural changes during hydration and dehydration, and this in turn greatly reduces the extent of hysteresis between the adsorption and desorption branches. Upon removing the backbone connectivity by breaking all peptide bonds in lysozyme, we find that the hysteresis shifts towards the lower humidity regime, and the water uptake capacity is significantly enhanced. We attribute these changes to the higher aggregation propensity of the constraint-free amino acids in dehydrated condition, and the formation of a spanning water network at high hydration levels.

Subjects

Subjects :
Medicine
Science

Details

Language :
English
ISSN :
20452322
Volume :
7
Issue :
1
Database :
Directory of Open Access Journals
Journal :
Scientific Reports
Publication Type :
Academic Journal
Accession number :
edsdoj.3515ff3e8ea345ea908c4aac632319cf
Document Type :
article
Full Text :
https://doi.org/10.1038/s41598-017-08561-2