Atomically Detailed Simulations of Concentrated Protein Solutions:  The Effects of Salt, pH, Point Mutations, and Protein Concentration in Simulations of 1000-Molecule Systems

2006 ◽  
Vol 128 (37) ◽  
pp. 12098-12110 ◽  
Author(s):  
Sean R. McGuffee ◽  
Adrian H. Elcock
Keyword(s):  
Protein Concentration ◽  
Point Mutations ◽  
Protein Solutions

scholarly journals Changes of secondary structure and surface tension of whey protein isolate dispersions upon pH and temperature

2014 ◽  
Vol 32 (No. 1) ◽  
pp. 82-89 ◽  
Author(s):  
M. Tomczyńska-Mleko ◽  
E. Kamysz ◽  
E. Sikorska ◽  
C. Puchalski ◽  
S. Mleko ◽  
...  
Keyword(s):  
Surface Tension ◽  
Secondary Structure ◽  
Whey Protein ◽  
Protein Concentration ◽  
Whey Proteins ◽  
Whey Protein Isolate ◽  
Protein Isolate ◽  
Protein Solutions ◽  
The Difference ◽  
Secondary Structure Of Proteins

The secondary structure of proteins in unheated and heated whey protein isolate dispersions and the surface tension of the solutions were investigated at different pH. Heating protein solutions at 80°C results in an increase of unordered structure. Nevertheless, the difference between the contents of unordered structure in the unheated and heated samples increases with increasing pH of the solution. At low protein concentrations the surface tension decreased with increasing protein concentration to about 5 mg/ml. For the heated solution, a similar trend was observed in the decrease in the surface tension with increasing concentrations of protein. In both cases, the curves depicting the surface tension as a function of protein concentration could be fitted to the exponential function with a negative exponent, but with the heated solutions lower values of surface tension were observed. Studies on the surface tension of whey protein isolate solutions prove that the unfolding of whey proteins, revealed by changes in the secondary structure, causes a decrease in the surface tension.

scholarly journals The Foaming Properties of Skim Milk Protein Concentrate

2019 ◽  
Vol 48 (4) ◽  
pp. 12-21
Author(s):  
Светлана Иванова ◽  
Svetlana Ivanova
Keyword(s):  
Protein Content ◽  
Protein Concentration ◽  
Milk Protein ◽  
Skim Milk ◽  
Milk Proteins ◽  
Protein Solutions ◽  
Foaming Properties ◽  
Foam Structure ◽  
Protein Concentrates ◽  
Protein Foam

Aerated products are popular all over the world, especially those with a foam structure. They are widely represented in the range of the global food market, including that of the Russian Federation. Traditionally, milk proteins are added to stabilize various foods. The present research explains how the concentration of skimmed milk proteins affects the foaming properties of concentrates. The experiment featured the influence of various protein concentrations (from 3.4 to 16.0%) on the foaming properties of reduced skim milk (9.2%) and of milk protein concentrates obtained by ultrafiltration. The research established their practical application for aerated products. The quality of protein foam was evaluated by foaming characteristics and foam stability. The distribution of protein foam bubbles by size was modelled using Erlang distribution. According to the simulation, the foams of protein solutions with a concentration of 12% were more stable. Concentrates with the highest protein content (16%) had not only a greater foaming, but also a greater stabilizing property. The protein samples density increased together with protein concentration. Similarly, the foaming characteristics of protein solutions (multiplicity and density of the foam) increased together with protein concentration. The stability of the foam structure was estimated by the half-life of the foam volume and the average diameter of the foam bubbles in the protein solutions. The most stable foams were those with the highest protein content in the concentrate. The protein concentrates from reduced skim milk were inferior in foaming characteristics to concentrates from milk that was not subjected to drying. However, the results suggest that the reduced skim milk and its protein concentrates are ideal for the production of aerated dairy products because they provide both good foaming and stability.

scholarly journals Effect of conjugated protein composed of porcine myofibril and Protaetia brevitarsis protein on protein functionality

2021 ◽  
pp. 1-10
Author(s):  
T.-K. Kim ◽  
H.-I. Yong ◽  
J.-M. Sung ◽  
H.W. Jang ◽  
Y.-S. Choi
Keyword(s):  
Protein Concentration ◽  
Partial Replacement ◽  
Protein Solutions ◽  
Protein Functionality ◽  
Emulsion Capacity ◽  
Lower Viscosity ◽  
Continuous Population ◽  
Breeding Efficiency ◽  
Protein Supply ◽  
Myofibril Protein

The replacement of conventional protein supply has been studied in the context of continuous population growth and the consequent environmental problems. Among protein substitutes, edible insects have gained relevance due to their high breeding efficiency. This study was conducted to estimate the effect of the partial replacement of porcine myofibril protein (pork protein; PP) with protein extracted from Protaetia brevitarsis (insect protein; IP) in protein-containing solutions and gels. The protein concentration was regulated at 30 and 1 mg/ml for gels and solutions, respectively, and the replacement percentages were increased by 20%. Gels containing IP showed a lower viscosity and thermal stability; the texture and surface of the gels were negatively impacted as the replacement percentage increased. Therefore, heating is not an appropriate method to induce the gelation of IP containing solutions. However, the replacement of PP with IP increased the foam capacity and emulsion capacity in solutions. In conclusion, we show that the partial replacement of PP with IP positively impacts on protein solutions but impairs their gelation.

scholarly journals Concentrated protein solutions investigated using acoustic levitation and small-angle X-ray scattering

2020 ◽  
Vol 27 (2) ◽  
pp. 396-404
Author(s):  
Pernille Sønderby ◽  
Christopher Söderberg ◽  
Christian G. Frankær ◽  
Günther Peters ◽  
Jens T. Bukrinski ◽  
...  
Keyword(s):  
Protein Concentration ◽  
Strength Parameter ◽  
Protein Solutions ◽  
Limited Sample ◽  
Saxs Data ◽  
X Ray Scattering ◽  
Levitated Droplet ◽  
Flow Through ◽  
Concentration Space ◽  
Selection Of

An acoustically levitated droplet has been used to collect synchrotron SAXS data on human serum albumin protein solutions up to a protein concentration of 400 mg ml−1. A careful selection of experiments allows for fast data collection of a large amount of data, spanning a protein concentration/solvent concentration space with limited sample consumption (down to 3 µL per experiment) and few measurements. The data analysis shows data of high quality that are reproducible and comparable with data from standard flow-through capillary-based experiments. Furthermore, using this methodology, it is possible to achieve concentrations that would not be accessible by conventional cells. The protein concentration and ionic strength parameter space diagram may be covered easily and the amount of protein sample is significantly reduced (by a factor of 100 in this work). Used in routine measurements, the benefits in terms of protein cost and time spent are very significant.

Inhibition of rat bronchiolar oxygen consumption by plasma proteins

1978 ◽  
Vol 44 (5) ◽  
pp. 659-665 ◽  
Author(s):  
R. M. Navari ◽  
J. L. Patterson
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Diffusion ◽  
Plasma Proteins ◽  
Protein Concentration ◽  
Protein Solutions ◽  
Physiological Salt Solution ◽  
Diffusion Cell ◽  
Diffusion Distance ◽  
Plasma Protein Concentration ◽  
Partial Explanation

The oxygen consumption of rat bronchioles suspended in a physiological salt solution containing plasma proteins was measured with the Cartesian diver microrespirometer. The oxygen consumption of the bronchiolar tissue 100–300 and 300–400 micrometer in diam was significantly (P greater than 0.01) reduced as the protein concentration of the suspending solution was increased from the low to the high extreme of the normal plasma physiological range and as the diffusion distance through the suspending medium was increased from 25 to 50 micrometer. The reduction in the bronchiolar oxygen consumption was significantly (P greater than 0.01) reversed by using 95% oxygen-5% nitrogen instead of air as the diffusing gas in the Cartesian diver. Measurements of the oxygen diffusivity in the protein solutions using a diaphragm diffusion cell showed a large decrease in the diffusivity as the plasma protein concentration was increased over the same concentration range used in the oxygen consumption studies. These results suggest that the reduction in oxygen consumption was secondary to a decrease in oxygen diffusion and may provide at least a partial explanation for the diffusion abnormalities which exist in noncardiogenic pulmonary edema in which there is an increase in microvascular membrane permeability to proteins.

scholarly journals Analysis of Fractal Structures in Dehydrated Films of Protein Solutions

Symmetry ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 123
Author(s):  
Maksim Baranov ◽  
Elena Velichko ◽  
Konstantin Greshnevikov
Keyword(s):  
Fractal Dimension ◽  
Protein Concentration ◽  
Dendritic Structure ◽  
Self Organization ◽  
Protein Solutions ◽  
Protein Solution ◽  
Fractal Structures ◽  
Temperature Dependences ◽  
Different Characteristics ◽  
The Relationship

The article deals with dendritic structures resulting from self-organization processes in aqueous solutions of albumin proteins. The methods for obtaining the structures and experimental results are presented. It is shown that dendrites are fractal structures that are symmetric under certain conditions of their formation and can have different characteristics depending on the isothermal dehydration of liquid samples. The fractal dimension of the structures in films of the albumin protein solution has been calculated. Dependences of the fractal dimension on the concentrations of salts and protein in the initial solutions and also on the dehydration temperature have been revealed. It has been shown that as the protein concentration in the solution grows, the salt concentration for the initiation of the dendritic structure formation increases. It has been found that the temperature dependences of the fractal dimension of the structures become smoother with increasing protein concentration in solutions. The relationship between geometric characteristics of dendrites and self-organization parameters during drying is discussed.

Effect of Surface Modification on Protein Deposition in Desiccated Droplets

2014 ◽  
Author(s):  
Michael J. Schertzer ◽  
Peter Lea ◽  
Ridha Ben-Mrad ◽  
Pierre E. Sullivan
Keyword(s):  
Fluorescence Intensity ◽  
Protein Concentration ◽  
Fluorescent Protein ◽  
Local Maximum ◽  
Protein Detection ◽  
Protein Solutions ◽  
Fluorescent Light ◽  
Hydrophobic Coatings ◽  
Protein Deposition ◽  
Physical Deposition

Detection of fluorescent signals from desiccated droplets is a useful tool for the analysis of microarray devices. This investigation presents an optical method for the observation of physical structures and protein deposition in desiccated droplets. Greyscale images of droplets containing red fluorescent protein solutions in water were recorded after desiccation. Images were obtained under both white and fluorescent light for droplets desiccated on glass and Teflon. Spots desiccated on glass were twice the size of those desiccated on Teflon. As such, average physical deposition and protein concentration was higher for Teflon spots. The average fluorescence intensity for spots desiccated on Teflon were four times greater than those desiccated on glass. For spots desiccated on glass, physical deposition and protein concentration increased with radial position, consistent with a coffee-ring pattern. The local maximum fluorescence intensity was highest at the center of the droplet. Protein deposition then decreased with increasing radius before increasing again toward the edge of the spot. These results suggest that desiccation of protein laden droplets on hydrophobic coatings, such as Teflon, may increase sensitivity of fluorescent protein detection while improving the uniformity of the fluorescent signal measured from the droplet.

scholarly journals THE EFFECT OF PURE PROTEIN SOLUTIONS AND OF BLOOD SERUM ON THE DIFFUSIBILITY OF CALCIUM

1926 ◽  
Vol 8 (5) ◽  
pp. 451-461 ◽  
Author(s):  
Robert F. Loeb ◽  
Keyword(s):  
Comparative Study ◽  
Blood Serum ◽  
Human Blood ◽  
Protein Concentration ◽  
Protein Solutions ◽  
Serum Globulin ◽  
Egg Albumin ◽  
Protein Ions ◽  
Isoelectric Points ◽  
Pure Protein

1. A comparative study has been made of the diffusibility of calcium in solutions of crystalline egg albumin, serum globulin, and human blood serum. 2. In all three of these solutions, at pH 7.4, molal Ca concentrations within the membrane are greater than the calcium concentrations in the outside solutions, quite in accordance with the Donnan theory. 3. At pH 7.4, the ratio of See PDF for Structure varies directly with the protein concentration whether the solution be one of egg albumin, serum globulin, or blood serum. This is also in accordance with the Donnan theory. 4. On the acid side of the isoelectric point of the proteins, the concentration of Ca outside becomes greater than the concentration in the solution of blood serum or pure protein, as is demanded by the Donnan theory. 5. The magnitude of the Ca ratios on the alkaline and acid sides of the isoelectric points is probably the resultant of the Donnan equilibrium and the formation of complex Ca-protein ions. Northrop and Kunitz have shown the probability of the existence of such ions in the case of Zn++, K+, and Li+, where satisfactory electrodes have been developed for E.M.F. measurements.

Salt and Acid-Induced Soft Tofu-Type Gels: Rheology, Structure and Fractal Analysis of Viscoelastic Properties as a Function of Coagulant Concentration

2014 ◽  
Vol 10 (4) ◽  
pp. 595-611 ◽  
Author(s):  
Murekatete Nicole ◽  
Zhang Caimeng ◽  
Karangwa Eric ◽  
Hua Yufei
Keyword(s):  
Soy Protein ◽  
Viscoelastic Properties ◽  
Protein Concentration ◽  
Gelation Time ◽  
Fractal Model ◽  
Angular Frequency ◽  
Protein Solutions ◽  
Transition Regime ◽  
Power Law Model ◽  
Dynamic Moduli

Abstract The coagulant concentration dependence on the rheological properties of acid and salt-induced soft tofu-type gels formed with heated soy protein solutions was investigated. All gels showed a clear gel-like behavior, with acid-induced gels having the highest storage modulus (G′). Increase in coagulant concentration resulted in higher G′ and shorter gelation time (tgel). The dependence of tgel on the coagulant concentration could be scaled with a power law model with R2 varying between 0.9535 and 0.9787. Also the dynamic moduli change over angular frequency fitted well the models: $${G^\prime}\sim{\rm{}}G_0^\prime {\omega^{n^\prime}}$$and $${G''}\sim {G^{\prime\prime}_0}^{\omega^{n}}$$. The increase in shear deformation at fracture and shear stress yielding was directly proportional to the increase in coagulant concentration. Both gels were found in the transition regime with varying protein concentration, when experimental data were scaled with a fractal model. Salt-induced gels had more uniform network pore size, finer and smoother surface texture than acid-induced gels. Dynamic moduli analysis of the gels was significantly affected by coagulant type and concentration (p<0.05).

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