7S Components Research Articles

Soybean protein isolate affects in vitro digestion properties of fermented indica rice starch by regulating its gel characteristics

Complex gels of fermented indica rice starch (FIRS) and soybean protein isolate (SPI) (0%–12%) were prepared to investigate the relationship between gel characteristics and digestive properties. During the co-gelatinization process, adding 9% SPI increased the resistant starch content from 19.83% to 30.43%, and the glycemic index decreased from 78.05 to 67.34, meaning that the glycemic index of the system changed from high to medium. Gel characteristics showed that 3% SPI enhanced the gel strength of FIRS, concurrently impeding water absorption capacity and reducing solubility. Moreover, adding SPI improved the gelatinization stability of FIRS (pasting temperature increased and breakdown decreased significantly, P < 0.05). Analysis of rheological properties revealed that hydrophobic, hydrogen bonding, and electrostatic interactions were at play between FIRS and SPI, with the hydrophobic interaction being the most prominent. Fractionation of SPI into its 11S and 7S globulin components and subsequent testing of FIRS–globulin mixtures demonstrated that 11S contributed to hydrophobic interactions and 7S contributed to hydrogen bonding, thus affecting viscoelasticity and starch order (short-range and long-range structures). Collectively, these findings suggest that SPI hinders the digestion of FIRS through hydrophobic interactions and the inhibition of gelatinization.

Physicochemical, structural and functional properties of protein isolates and major protein fractions from common vetch (Vicia sativa L.)

Common vetch (CV), a leguminous crop cultivated for green manure and fodder rich in protein and starch, is widespread over much area of the northern hemisphere. Its seeds can be used as a protein source to human consumption. CV protein isolates (CVPI) and major protein fractions (CV albumin protein, CVAP; CV globulin protein, CVGP; CV glutelin protein, CVGTP) from 4 samples were investigated the properties to facilitate full use of protein resources. Protein comprises 27.70 %–32.14 % of the dry CV seed weight, which is mainly composed by CVAP (26.79 %–56.12 %) and CVGP (22.78 %–52.42 %). CVPI, CVAP and CVGP mainly presented 7S and 11S components. CVGTP mainly contained the 11S component. They showed difference in thermal properties and surface hydrophobicity. Circular dichroism data showed that α-helix was their major secondary structure. CVPI and major protein fractions exhibited a U-shape protein solubility. CVPI and CVAP had advantages in emulsifying and foaming properties. This study provided novel insights on unexploited sources of CV proteins with interesting characteristics in terms of potential uses as protein-based foods.

Effect of water-in-oil-in-water (W/O/W) double emulsions to encapsulate nisin on the quality and storage stability of fresh noodles.

Rock-bean protein (RP) was extracted from wild rock beans by ultrasonic treatment and microwave extraction. The RP has a high content of 7S and 11S globulin components and good heat stability. Subsequently, water-oil-water double emulsions were prepared using a water core containing nisin, momordica charantia extract (MCE), and Lactobacillus plantarum as functional additives, corn oil as the intermediate wall, and RP/gum arabic (GA) as the outer wall material. For a ratio of corn oil to water of 5:1, the maximum encapsulation efficiency was 28.22%, and RP/GA had good dispersion characteristics, where the smallest average particle size was achieved for a 1:1 ratio. Finally, the microcapsules were used to study the effect of its addition to noodles. The addition of 2wt% of the microcapsules to low-gluten flour resulted in a dough with suitable rheology, and can extend the shelf life of the fresh noodles prepared using this dough.

Abstract A47: The immunoproteosome mediates resistance to natural killer cell killing

Abstract We identified the immunoproteosome as a mediator of resistance to natural killer (NK) cell killing through a genome-wide activation CRISPR screen. The immunoproteosome is a modified proteolytic complex composed of a catalytic 20S core and a regulatory 11S component. An essential function of the immunoproteosome is to degrade intracellular proteins that are eventually presented as antigens on the cell surface by the major histocompatibility complex (MHC) I. We validated several subunits that play a critical role in regulating responses to NK cells, specifically, PSMA1, PSMB6 and PSME1, which encode the alpha subunit of the 20S catalytic proteosome, the beta subunit of the 20S proteosome, and the alpha subunit of the 11S regulator, respectively. While several studies have reported that proteasome inhibitors sensitize cancer cells to NK cell killing, the exact mechanisms of these inhibitors are not well understood. Our data indicate that these proteasome components may be attractive targets to improve cancer cell response to NK cell-based therapies. Note: This abstract was not presented at the conference. Citation Format: Joyce Pasion, Hans Guido Wendel. The immunoproteosome mediates resistance to natural killer cell killing [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr A47.

Biochemical characteristics of soybean seeds for selection of food varieties

The aim and tasks of the study.The research purpose was to study biochemical characteristics that determine seed quality, including peculiarities of changes in total protein and isoflavone contents, component composition and level of 7S and 11S globulins, their ratio in soybean seed protein of varieties, F2 - F8 hybrids of different genetic origin for development of criteria for selection of food soybean genotypes.Material and methods. The investigation was conducted on soybean (Glycine max L.) varieties, F2 – F8 hybrid populations bred in Ukraine or other countries and their parents as well as on genotypes with known status of glicinine and β-conglicinine genes from the National Plant Germplasm System. Protein content was determined by Kjeldal method on a Kjltec Auto-1030. 7S and 11S globulins were extracted and identified by a method developed in the Laboratory of Plant Biochemistry (Patent 42181).Total isoflavones were determined by spectrophotometrically.Results and discussion. It was shown that the test soybean varieties considerably differed by the total protein and isoflavone contents as well as by 7S and 11S globulin fractions. Intervarietal polymorphism of component composition of 7S and 11S globulins was shown electrophoretically. Peculiarities of 7S and 11S globulin component composition and contents as well as their ratios were described for genotypes of different phylogenetic origin, F3 - F8 hybrids and their parents. An express method for extraction and identification of 7S and 11S globulins from soybean seeds was developed for estimation of breeding material by these characteristics.Conclusions. We observed considerable variations in the studied biochemical indices, which determine nutritional value of soybean seeds. We conclude that these results can be used for selection of food soybean varieties

Correlation Between Protein Hydrolysates and Color During Fermentation of Mucor-Type Douchi

The correlations between the color of douchi and different protein hydrolysates from the post-fermentation period were analyzed. The results showed that peptides had the highest correlation with the color change, while free amino acids were second, which indicated that peptides and free amino acids were more involved in the Maillard reaction. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the 7S component may be more involved in the Maillard reaction during the pre-fermentation of douchi, and that 11S subunits may be more involved in the formation of melanin in the initial stage of post-fermentation. The water-soluble extracts of two douchi samples in the most rapid formation stage of melanin were analyzed by reversed phase-high performance liquid chromatography. The results showed that the hydrophilicity of hydrolysates decreased depending on color. Meanwhile, the amino acid analyses demonstrated that the four amino acids with the maximum loss ratios were all hydrophilic in this stage, which indicated a loss in the hydrophilic components due to their involvement in the Maillard reaction.

The Native Structure and Composition of the Cruciferin Complex in Brassica napus

Globulins are an important group of seed storage proteins in dicotyledonous plants. They are synthesized during seed development, assembled into very compact protein complexes, and finally stored in protein storage vacuoles (PSVs). Here, we report a proteomic investigation on the native composition and structure of cruciferin, the 12 S globulin of Brassica napus. PSVs were directly purified from mature seeds by differential centrifugations. Upon analyses by blue native (BN) PAGE, two major types of cruciferin complexes of ∼ 300-390 kDa and of ∼470 kDa are resolved. Analyses by two-dimensional BN/SDS-PAGE revealed that both types of complexes are composed of several copies of the cruciferin α and β polypeptide chains, which are present in various isoforms. Protein analyses by two-dimensional isoelectric focusing (IEF)/SDS-PAGE not only revealed different α and β isoforms but also several further versions of the two polypeptide chains that most likely differ with respect to posttranslational modifications. Overall, more than 30 distinct forms of cruciferin were identified by mass spectrometry. To obtain insights into the structure of the cruciferin holocomplex, a native PSV fraction was analyzed by single particle electron microscopy. More than 20,000 images were collected, classified, and used for the calculation of detailed projection maps of the complex. In contrast to previous reports on globulin structure in other plant species, the cruciferin complex of Brassica napus has an octameric barrel-like structure, which represents a very compact building block optimized for maximal storage of amino acids within minimal space.

Functional Properties of Proteins from Lima Bean (Phaseolus lunatus L.) Seeds

Functional properties were identified for the total globulin (TG), 7S and 11S fractions of Lima bean (Phaseolus lunatus L.) seeds. The 11S component accounted for 58.3% of TGs and the 7S for 41.7%. Solubility was higher in the 7S fraction, especially at alkaline pHs. Water-holding capacity was similar (3 g water/g sample) in both globulin fractions. Oil-holding capacity was higher in the 11S fraction, which also exhibited better foaming capacity and foam stability than the 7S and TG fractions at alkaline pHs. The TG and 7S fractions exhibited low emulsifying capacity and emulsion stability at different pHs (5, 7 and 9), but the 11S fraction had relatively higher values. In suspension at low concentrations, all fractions exhibited shear-thinning (pseudoplastic) behavior. The studied Lima bean globulin fractions exhibit functional properties which make them potentially apt for use in some industrial food systems.

Epidermal Growth Factor Receptor vIII Expression in U87 Glioblastoma Cells Alters Their Proteasome Composition, Function, and Response to Irradiation

Little is known about the factors that influence the proteasome structures in cells and their activity, although this could be highly relevant to cancer therapy. We have previously shown that, within minutes, irradiation inhibits substrate degradation by the 26S proteasome in most cell types. Here, we report an exception in U87 glioblastoma cells transduced to express the epidermal growth factor receptor vIII (EGFRvIII) mutant (U87EGFRvIII), which does not respond to irradiation with 26S proteasome inhibition. This was assessed using either a fluorogenic substrate or a reporter gene, the ornithine decarboxylase degron fused to ZsGreen (cODCZsGreen), which targets the protein to the 26S proteasome. To elucidate whether this was due to alterations in proteasome composition, we used quantitative reverse transcription-PCR to quantify the constitutive (X, Y, Z) and inducible 20S subunits (Lmp7, Lmp2, Mecl1), and 11S (PA28alpha and beta) and 19S components (PSMC1 and PSMD4). U87 and U87EGFRvIII significantly differed in expression of proteasome subunits, and in particular immunosubunits. Interestingly, 2 Gy irradiation of U87 increased subunit expression levels by 16% to 324% at 6 hours, with a coincident 30% decrease in levels of the proteasome substrate c-myc, whereas they changed little in U87EGFRvIII. Responses similar to 2 Gy were seen in U87 treated with a proteasome inhibitor, NPI0052, suggesting that proteasome inhibition induced replacement of subunits independent of the means of inhibition. Our data clearly indicate that the composition and function of the 26S proteasome can be changed by expression of the EGFRvIII. How this relates to the increased radioresistance associated with this cell line remains to be established.

Effect of succinylation on the functional and physicochemical properties of alpha-globulin, the major protein fraction from Sesamum indicum L.

alpha-Globulin the major protein fraction from Sesamum indicum was succinylated to different levels and the effect of the chemical modification was evaluated both on the functional and physicochemical properties. The results suggest that the pH of minimum solubility shifted to the more acidic side (pH approximately 4.5-5.5) for the succinylated alpha-globulin whereas for control alpha-globulin the pH of minimum solubility was 6.5. Succinylation also increased emulsion activity and emulsion stability of the protein. The emulsion stability increased from a control value of 53 +/- 3 s to a value of 122 +/- 5 s. Bulk density, water absorption capacity, oil absorption capacity, foam capacity and foam stability were evaluated in phosphate buffer (pH 7.0) containing 0.5 M sodium chloride and all these properties showed increased values as a result of succinylation. Ultracentrifugation studies showed that the % composition of 7S component increases with concomitant decrease in that of 11S fraction with the increase in percentage of succinylation. Further increase in succinylation resulted in only 2S component which is a dissociated form of 11S and/or 7S protein fractions. The fluorescence emission studies showed a decrease in the fluorescence emission intensity of alpha-globulin as a result of succinylation. The thermal stability of the protein molecule decreased due to progressive succinylation as indicated by decrease in the apparent thermal denaturation temperature from a control value of 84 to 62 degrees C at a succinylation level of 40%. These results suggest that succinylation improves the functional characteristics of alpha-globulin. Such changes in the functional properties have been attributed partly to the dissociation of the protein molecule at higher levels of succinylation and the increase in the net negative charge on the protein.

High Spin Mn Molecular Clusters: Spin State Effects On the Outer Core-Level Multiplet Structures

AbstractOxo-bridged manganese polynuclear complexes have applications in a variety of technologies, such as single-molecule nanomagnets, catalysis and photosynthetic redox chemistry. The reason that these types of compounds are capable of such important and varied technologies is thought to be because they possess ground states with large spin values. However, the electronic, structural and magnetochemical relationships are not well understood and need to be thoroughly investigated to adequately explain why Mn is such an integral part of so many useful processes. X-ray photoemission spectroscopy was used to study the Mn 3p, 3s and valence band electronic behavior as a function of Mn cluster structural properties, where the cluster size and nuclearity are systematically varied. Results show a chemical shift of the Mn 3p3/2,1/2 spin-orbit pair related to the cluster size and nuclearity. Also, the Mn 3s 7S and 5S final state multiplet components shift since they involve the binding energy of a ligand valence electron. In addition, the branching ratio of the 7S:5S states is related to the 3s–3d electron correlation. Specifically, in the 7S state, the remaining 3s electron is well correlated with 3d electrons of parallel spin, while in the 5S state the two spins are antiparallel. Changes in this electron correlation are clearly observed in the 7S:5S branching ratio as a function of cluster size and ligand electronegativity.

Thermal Behavior and Nonfreezing Water of Soybean Protein Components

ABSTRACTThermal denaturation and hydration of two soybean protein components were studied using differential scanning calorimetry (DSC). Results showed that temperature of denaturation (Td) of both 11S and 7S globulins decreased sharply with an increase in water content. Enthalpy of denaturation (ΔHd) of 11S increased with increasing water content at first, and then leveled off at high water content. However, ΔHd of both 7S and 11S components in 7S samples first increased and then decreased at high water content. The preparation method of samples influenced the ΔHd value significantly but had little effect on the Td. Nonfreezing water was determined from the DSC results. It increased in both 11S and 7S as water content increased but was more abundant in 7S, probably because of different compositions and structures. Threshold value of water content for the appearance of freezing water was 0.30–0.32 h (g of water/g of protein, mass ratio) for 11S. The water absorbed by both 11S and 7S during denaturation increased quickly at low water contents and remained almost constant at high water contents. The results were attributed to different structure and conformation of proteins before and after denaturation.

Soybean Protein Products as Regulators of Liver Low-Density Lipoprotein Receptors. I. Identification of Active β-Conglycinin Subunits

The ability of the different soy globulins to upregulate low-density lipoprotein (LDL) uptake and metabolism in human hepatoma cells (Hep G2) was investigated, in an attempt to identify peptide components responsible for the upregulation of the LDL receptor. In parallel, the metabolism of soy globulins, added to the culture medium, was investigated by two-dimensional electrophoresis. After addition of soy globulins, there were no marked changes in the cell protein pattern, as evaluated by general protein staining. By immunodetection, intact 7S components were observed both free in the culture medium and bound to plasma membranes. Inside cells, α + α‘ subunits in their native forms were not detectable, whereas most of the β chain was found unchanged. Largely unmodified soybean proteins were detected in a lysate of 11S-treated cells. Incubation of Hep G2 cell with purified α + α‘ from 7S sharply increased uptake and degradation of 125I-LDL added to the culture medium, whereas the β chains were ineffective; ...

Stress-relaxation behaviour of spread films and coalescence stability of o/w emulsions formed by succinylated legumin from faba beans (Vicia faba L.)

The influence of succinylation on film-forming properties of 11S globulin (legumin) from faba beans was studied on planar films and o/w emulsions. The stress-relaxation behaviour of films spread at the air/water interface was investigated by means of the pendent drop technique in combination with axial symmetric drop shape analysis. Using analytical ultracentrifugation, changes in the sedimentational behaviour of the protein and coalescence pressure of protein-stabilised o/w emulsions after modification were measured. The 11S protein molecule dissociates into 7S and 3S components with progressive succinylation. At the highest degree of succinylation (95%), only the monomeric 3S subunits could be detected. Succinylation leads to a decrease of surface dilation elasticity, to an increase of the corresponding viscosity and to higher relaxation times which characterise the stress relaxation process. These effects, which are maximised in the range of 65% succinylation, clearly point to the formation of a very viscous film-structure at the interface. The marked increase in the coalescence pressure of emulsions (more than 40-fold) after succinylation of the legumin also confirms the formation of strong interfacial films at o/w interfaces after emulsification.

Partial Purification and Characterization of the 15S Globulin of Soybeans, a Dimer of Glycinin

During preparative gel filtration of crude glycinin (11S ultracentrifugal component of soybean proteins), the second fraction that eluted just before the major peak (glycinin) was found to be enriched in the 15S component. Gel electrophoresis under denaturing conditions indicated that this fraction was identical to glycinin, suggesting that the 15S component is an aggregate of glycinin. Upon rechromatography of pooled, freeze-dried, 15S-enriched (50% 15S prior to freeze-drying) fractions the purity of 15S was only 39%, apparently because of partial dissociation of the 15S fraction into 11S component as a result of dialysis and freeze-drying. When freeze-drying was avoided, two successive rechromatographies yielded 15S preparations of 63−66% purity. However, on storage in solution, the purified 15S fraction slowly dissociated into 11S component; after 20 days, the composition was 47% 15S and 31% 11S. Gel electrophoresis and amino acid analysis confirmed the identity of the 15S fraction with glycinin. Molec...

Hydrodynamic Characterization of Lupin Proteins: Solubility, Intrinsic Viscosity, and Molar Mass

The solubility, intrinsic viscosity ([η]), and sedimentation behavior of a lupin protein system extracted from Lupinus luteus seeds have been determined. The results were compared with those published in the literature for soy proteins. The relationship between solubility and pH for the lupin protein isolate was similar to that reported in literature for soy isolates. The [η] of the lupin protein isolate was ∼7 mL/g. These values are comparable to those obtained by other authors for soy proteins. Sedimentation velocity studies suggested that there are three main globulins in lupin protein with sedimentation coefficients of 13, 7, and 2 S. The molar mass of the major lupin globulin (390 000 g/mol) was slightly higher than reported for the soy 11S globulin (340 000 g/mol), but the lupin 7S component gave a much smaller value (105 000 g/mol) than the soy 7S (180 000 g/mol). The consequences in thickening and thermal gelation properties of the lupin protein system are discussed. Keywords: Lupin proteins; solubility; intrinsic viscosity; molar mass

Expression of Sporophytic Storage Proteins in the Corm of the Quillwort (Isoetes echinospora Dur.).

Parenchyma cells from the corm tissue of the aquatic lycopod Isoetes echinospora Dur. were shown by electron microscopy to be packed with amyloplasts, lipid bodies, and protein bodies. The protein bodies are morphologically similar to those identified in seeds and certain vegetative tissues of higher plants. Globoid-containing protein bodies (1-10 [mu]m) isolated in a sucrose gradient possessed a buoyant density of 1.28 g/mL and contained globulin (salt-soluble) proteins. Sucrose gradient centrifugation of crude globulins revealed only two components with mean sedimentation coefficients of approximately 2S and 11S. The 2S component, designated VSP-IsA, was composed of a 15.7-kD polypeptide. The 11S component, designated VSP-IsB, had a molecular mass of 215 kD as estimated by gel filtration and was composed of 39- to 42-kD polypeptides. Two-dimensional gel electrophoresis showed constituent polypeptides distinguished by differences in net charge and molecular mass. Affinity-purified antibodies against VSP-IsA and VSP-IsB prepared and used as probes on immunoblots cross-react only with their specific antigens, suggesting that the proteins are not immunologically related. Indirect immunolocalization studies confirmed that VSP-IsB is deposited in protein bodies. These globulin proteins, like those from some seeds, form the principal storage reserves of the corm tissue.

Effect of γ‐irradiation on soya bean proteins

AbstractThe properties of soya bean proteins following γ‐irradiation (5–20 kGy) were investigated in connection with protein denaturation. Irradiation doses above 10 kGy caused a decrease in 7S and 11S components and an increase in 2S and 15S components (P &lt; 0.05). However, subunit patterns determined by electrophoresis were not changed appreciably over the entire irradiation dose range. In the differential scanning calorimetry thermogram, the denaturation temperatures of 11S and 7S components were not affected by γ‐irradiation, while increased irradiation dose caused a decrease in the enthalpy values of 11S and 7S components due to protein denaturation. Changes in the circular dichroism spectra and tryptophan fluorescence intensity (P &lt; 0.05) were observed only at 20 kGy.

Total proteins and 11S protein fraction (Helianthinin) of sunflower seed (Helianthus annuus L.) — Effect of acetylation and succinylation

AbstractThe total proteins and helianthinin (11S) from sunflower seeds were chemically modified by acetylation and succinylation. The extent of acetylation of the total proteins and helianthinin were 12%, 51%, 52%, 56% and 12%, 36%, 69%, 71%, respectively, while the extent of succinylation were 8%, 21%, 33%, 49% and 10%, 30%, 44%, 61%, respectively. The extent of modification was monitored by the availability of free lysyl residues in the proteins. The ultraviolet absorption maximum shifted to higher wavelengths in total proteins and in helianthinin; there was also an increase in absorbance in the 260 nm wavelength, as a function of increased chemical modification. The sedimentation velocity profile indicated the dissociation of the proteins to low molecular weight fraction (2S) through a 7S component. The dissociation occurred at low modification levels in both total proteins and in helianthinin. There was a gradual red shift and quenching in the fluorescence emission maximum at higher modification levels indicating the denaturation of the proteins as a result of this chemical modification. The change in absorbance as a function of temperature indicates minor changes suggesting that the conformation of the proteins is already altered to significant extents due to the chemical modification.

Analytical Evaluation of the Globulin Proteins of Cottonseed Meals

Abstract A method for the analytical evaluation of the globulin (saltsoluble) fraction of cottonseed meals has been developed. Cottonseed of 14% moisture content is stored for 6 and 9 weeks at 50°C. Meals obtained after seeds are defatted with pet ether are analyzed for nitrogen content, and then extracted with water. Residues are then extracted with 10% NaCI to isolate the globulin fraction. This fraction is characterized by liquid chromatography (LC) and gel electrophoresis (LDS-PAGE). Kjeldahl analyses showed no loss of nitrogen in meals from stored seed compared with those from unstored seeds. However, a large decrease in NaCI extractable nitrogen was noted in meals from stored cottonseed. LC and LDS-PAGE showed that an alteration of the globulin proteins occurred during storage, and the method demonstrated a progressive change in the 11S and 7S components of the globulin fraction.