Modulating Weak Protein-Protein Cross-Interactions by the Addition of Free Amino Acids at Millimolar Concentrations.

In this paper, we quantify weak protein-protein interactions in solution using cross-interaction chromatography (CIC) and surface plasmon resonance (SPR) and demonstrate that they can be modulated by the addition of millimolar concentrations of free amino acids. With CIC, we determined the second osmotic virial cross-interaction coefficient () as a proxy for the interaction strength between two different proteins. We perform SPR experiments to establish the binding affinity between the same proteins.

Effect of extraction method on the calcium binding capacity of faba bean globulin fractions at various pH.

Faba bean ingredients are rich in proteins and good sources of calcium (Ca), although containing phytic acid (PA) molecules. PA, a polyphosphate compound, can affect the bioavailability of minerals/proteins through complex formation. This study evaluates the impact of two extraction processes, Alkaline Extraction-IsoElectric Precipitation (AE-IEP) and Sequential Extraction (SE), on the ability of faba bean globulin systems to bind added calcium ions.

Heat-induced gelation of mixtures of micellar caseins and plant proteins in aqueous solution.

The aim of this work was to investigate how the heat-induced gelation of micellar casein (MC)-plant protein mixtures in aqueous solution is affected by protein composition (MC/plant proteins = 100/0 to 0/100) and total protein content (4%, 6% and 8% w/w) at pH 5.8 and 6.0.

Specific effect of calcium ions on thermal gelation of aqueous micellar casein suspensions.

Aqueous suspensions of micellar casein (MC) gel when heated above a critical temperature that depends on the pH. The effect of adding CaCl and EDTA on thermal gelation was studied in order to assess the effect of increasing or decreasing the amount of bound Ca on the process. The effect of adding NaCl was investigated in order to distinguish the effect of Ca binding from the effect of screening of electrostatic interactions.

How High Concentrations of Proteins Stabilize the Amorphous State of Calcium Orthophosphate: A Solid-State Nuclear Magnetic Resonance (NMR) Study of the Casein Case.

Understanding how proteins stabilize amorphous calcium ortho-phosphate (ACP) phases is of great importance in biology and for pharmaceutical or food applications. Until now, most of the former investigations about ACP-protein stability and equilibrium were performed under conditions where ACP colloidal nanoclusters are surrounded by low to moderate concentrations of peptides or proteins (15-30 g L). As a result, the question of ACP-protein interactions in highly concentrated protein systems has clearly been overlooked, whereas it corresponds to actual industrial conditions such as drying or membrane filtration in the dairy industry for instance.

The influence of cheese composition and microstructure on the diffusion of macromolecules: A study using Fluorescence Recovery After Photobleaching (FRAP).

In cheese technology, the diffusion phenomena are crucial during ripening. The technique of Fluorescence Recovery After Photobleaching was applied for the first time on real cheese, in order to investigate the relationships between molecular diffusion and the cheese composition and/or its microstructure. Measured effective diffusion coefficients in soft and hard cheese of a group of dextrans (10-500 kDa) were found to be in the same order of magnitude with values observed when using a comparable non-fat model cheese (∼ 0.

Flexibility and Charge of Solutes as Factors That Determine Their Diffusion in Casein Suspensions and Gels.

This work explores the influence of both the physicochemical characteristics of solutes and the solute-matrix interactions on diffusion in casein systems. Diffusion coefficients of three solute groups (dextrans, proteins, and peptides) presenting different physicochemical characteristics, such as molecular flexibility and charge, were measured using the technique of fluorescence recovery after photobleaching (FRAP). The casein systems had the same casein concentration, but different microstructures (suspension or gel), and/or a different pH (5.

Diffusion of solutes inside bacterial colonies immobilized in model cheese depends on their physicochemical properties: a time-lapse microscopy study.

During cheese processing and ripening, bacteria develop as colonies. Substrates and metabolites must then diffuse either from or into the colonies. Exploring how the inner cells of the colony access the substrates or get rid of the products leads to study the diffusion of solutes inside bacterial colonies immobilized in cheese.