Formation of rice protein fibrils is highly sensitive to the different types of metal ions: Aggregation behavior and possible mechanisms

Serum protein albumin and chromium: Mechanistic insights into the interaction between ions, nanoparticles, and protein

The interaction of human proteins and metal species, both ions and nanoparticles, is poorly understood despite their growing importance. These materials are the by-products of corrosion processes and are of relevance for food and drug manufacturing, nanomedicine, and biomedical implant corrosion. Here, we study the interaction of Cr(III) ions and chromium oxide nanoparticles with bovine serum albumin in physiological conditions. This study combined electrophoretic mobility measurements, spectroscopy, and time-of-flight secondary ion mass spectrometry with principal component analysis. It was determined that neither metal species resulted in global albumin unfolding. The Cr(III) ions interacted strongly with amino acids found in previously discovered metal binding sites, but also were most strongly implicated in the interaction with negatively charged acid residues, suggesting an electrostatic interaction. Bovine serum albumin (BSA) was found to bind to the Cr2O3 nanoparticles in a preferential orientation, due to electrostatic interactions between the positive amino acid residues and the negative chromium oxide nanoparticle surface. These findings ameliorate our understanding of the interaction between trivalent chromium ions and nanoparticles, and biological macromolecules.

Fibrillation of soy protein isolate in the presence of metal ions: Structure and gelation behavior

The structure and functional properties of protein fibrils are closely related to environmental factors in fibrillation. Herein, soy protein isolate fibrils (SPIFs, 22 mg/mL) were prepared under acid-heating conditions in the presence of 100 mM metal ions (K+, Na+, Ca2+, Mg2+, and Fe3+). Except for Fe3+, fibrillation and subsequent larger fibril aggregates were promoted, ultimately leading to gel formation. Compared with K+ or Na+, the addition of Ca2+ or Mg2+ resulted in more organized SPIF structures with increased β-sheet contents and higher ThT fluorescence intensities. Furthermore, both of them resulted in longer fibrils with an average contour length of 700-800 nm, which significantly enhanced the storage modulus. However, the presence of Fe3+ accelerated protein hydrolysis and inhibited SPIF formation, resulting in samples consistently exhibited liquid behavior. These findings provide a foundation for understanding the influence of metal ions on regulating the fibrillation and gelling properties of SPIFs.

Preparation and Formation Mechanism Study of Antibiofilm Coating Based on Phase Transition of Glutenin

The surface of food processing equipment is easily affected by biofilm-forming bacteria, leading to cross-contamination and food safety hazards. The critical issue is how to endow the surface of contact materials with antibacterial and antibiofilm abilities. A sustainable, stable, and antibiofilm coating was prepared by phase transition of glutenin. The disulfide bonds in glutenin were reduced by tris(2-carboxyethyl)phosphine, triggering the phase transition of glutenin. Hydrophobic interactions and intermolecular disulfide bonds may be the primary forces. Furthermore, the phase-transited products formed a nanoscale coating on the surface of stainless steel and glass under their own adhesion force and gravity. The coating exhibited good stability in harsh environments. More importantly, after 3 h of direct contact, the colony of Escherichia coli and Staphylococcus aureus decreased by one logarithm. The amount of biofilm was observed to be significantly decreased through optical microscopy and scanning electron microscopy. This article provides a foundational module for developing novel coatings.

Specific ions effect on aggregation behaviors and structural changes of amyloid fibrils from rice glutelin

Metal ions have been considered as an important factor on fibrils assembly. Herein, a comprehensive analysis of specific ions effect on fibril formation and structural changes was investigated. The addition of ions (except Zn2+) accelerated the aggregation kinetics of rice glutelin fibrils (RGFs) from 0.93 to 1.28-2.19 h-1. In addition, the fibrillization rate followed the order of NH4+ > Li+ > Na+ > K+ > Cu2+ > Mg2+ > Ca2+ > Zn2+. The highest yield and length of fibrils were observed with Ca2+, probably due to the ionic bridging effect and hydrated capacity of Ca2+. However, Cu2+ reduced the fibrils yield, which was attributable to the fact that Cu2+ disrupted β-sheet structure and inhibited the transition of monomer to fibrils. The polymorphism of fibrils was observed with different salts, and the light metals presented a superior effect on fibrils formation than heavy metals. Overall, this work will provide a further information into how to tune the structure of RGFs using various ions.