Comparative Study of the Structural and Functional Properties of Membrane-Isolated and Isoelectric pH Precipitated Green Lentil Seed Protein Isolates

The demand for isolated seed proteins continues to increase but functionality in food systems can be greatly dependent on the extraction method. In this work, we report the physicochemical and functional properties of lentil seed proteins isolated using various protocols. Lentil flour was defatted followed by protein extraction using isoelectric pH precipitation (ISO) as well as NaOH (MEM_NaOH) and NaCl (MEM_NaCl) extractions coupled with membrane ultrafiltration. The MEM_NaCl had significantly (p < 0.05) higher protein content (90.28%) than the ISO (86.13%) and MEM_NaOH (82.55%). At pH 3–5, the ISO was less soluble (2.26–11.84%) when compared to the MEM_NaOH (25.74–27.22%) and MEM_NaCl (27.78–40.98%). However, the ISO had higher yield and protein digestibility (48.45% and 89.82%) than MEM_NaOH (35.05% and 77.87%) and MEM_NaCl (13.35% and 77.61%), respectively. Near-UV circular dichroism spectra showed that the MEM_NaOH had loose tertiary conformation at pH 3, 5, 7 and 9 while ISO and MEM_NaCl had more compact structures at pH 7 and 9. The three protein isolates formed better emulsions (lower oil droplet sizes) at pH 7 and 9 when compared to pH 3 and 5. In contrast, foaming capacity was better at pH 5 than pH 3, 7, and 9.

Isolation and Characterization of Red Bean and Green Bean Protein using the Extraction Method and Isoelectric pH

Stunting children need food intake with higher protein and essential amino acids such as lysine and leucine than normal children. Red Beans (Phaseolus Vulgaris L.) and Green Beans (Phaseolus Radiatus L.) have protein content, respectively 22.07 ± 0.13% and 19.99 ± 0.07%, and are rich in essential amino acids lysine and leucine needed by a stunting child. The Development of food products with high protein concentrations (high protein food) such as isolates/protein concentrates is an important subject that must be done. This study aims to determine the technique of isolating red bean and green bean protein through extraction and deposition methods at isoelectric pH. The research method used is an experimental method with descriptive data analysis. Identification of isoelectric pH of red bean and green bean protein is done through electrophoretic mobility (cm2/Vs) testing on samples that have been conditioned at 3 different depositional pHs namely pH 3.00, 4.00, and 5.00. The results showed the isoelectric pH value of red bean and green bean protein, namely pH 4.56 and pH 4.81 respectively, where the pH had electrophoretic mobility values equal to zero. The process of isolating red bean and green bean protein produces protein powder with a protein content of 79.22 ± 0.06% and 80.69 ± 0.06%, respectively. Based on the weight yield, red bean and green bean protein concentrate powder had a yield of 14.88% and 16.75%, respectively.

Unravelling the fibrillation mechanism of ovalbumin in the presence of mercury at its isoelectric pH

Mercuric chloride triggered ovalbumin aggregation pathway and its resemblance to Nephila clavipes.

The Investigation of Alpha-Tubulin Differential Expression in Oligodendroglioma Brain Tumor Aiming MALDI-TOF-TOF

Background: Tubulin is known as a heterodimer protein, which includes alpha and beta tubulin subunits. This structural protein plays important roles in pathogenesis and healing different diseases. Biomarkers help in fast and accurate detection of cancer. Proteomic studies can be useful both in biological and clinical research, also help obtain protein expression profiles by using twodimensional electrophoresis, mass spectrometry, and bioinformatics tools. Finding candidate proteins as cancer biomarkers is an interesting area in proteomic investigations. Methods: In the present study, the total protein content of healthy cells of the brain and brain tumor cells were extracted, purified and quantified by Bradford assay. Two-dimensional electrophoresis used for protein separation followed by statistical analysis. Primary protein detection was performed based on the differences in isoelectric pH, the molecular weight of proteins and protein data banks, which was further confirmed by Matrix Assisted Laser Desorption Ionisation-Time-of-Flight (MALDITOF-TOF). Results: In this study, an alpha-tubulin expression found changed (overexpression) in Oligodendroglioma tumors comparing control identified by proteomics analysis. Also, alphatubulin position showed in the oligodendroglioma tumors cluster diagram. Conclusion: Proteome analysis approach has allowed biology and medical studies. Alpha-tubulin introduced as a candidate biomarker for the diagnosis and prediction of oligodendroglioma tumors.

Functional Properties of Lupinus angustifolius Seed Protein Isolates

Protein isolates prepared by alkaline solubilization followed by isoelectric precipitation and freeze-drying from six varieties of Lupinus angustifolius (Haags Blaue, Sonate, Probor, Borlu, Boregine, and Boruta) grown in Mexico were evaluated for functional properties: nitrogen solubility, water-holding capacity (WHC), oil holding capacity (OHC), emulsion activity index (EAI), emulsion stability index (ESI), foaming capacity (FC), foam stability (FS), and gelling minimum concentration (GMC). The nitrogen solubility values, WHC, OHC, and FC did not show significant differences between the protein isolates. The solubility of the isolates was minimal at pH of 4.0 and 5.0 while the regions of maximum solubility were found at pH of 2.0 and 10.0. There were significant differences in EAI and ESI depending on the varieties used. The isolates of the Boregine and Borlu varieties showed the highest EAI with 29.3 and 28.3 m2 g−1, respectively, while the lowest index was recorded in the isolate obtained from the Sonate variety (24.6 m2 g−1). Like solubility, these indices also increased at both extremes of pH evaluated; both properties were minimal in the isoelectric pH range (4.0 to 5.0).

The adsorption behaviour of lysozyme as a potential antibiofouling agent

Introduction: Biofilms can be problematic or beneficial. Reports on the underlying adsorption in such context-dependent fouling phenomena have been extensive. However, the mechanisms involved is scarce and appears adsorbate or foulant-specific. Methods: In this study, attenuated total reflection infrared spectroscopy was used to probe the solid-liquid interfacial phenomena involving lysozyme for assessing its surface antibacterial actions. Results: Lysozyme preferentially adsorbed more on to the hydrophilic coated ZnSe IR prism than to an uncoated ZnSe IR prism. Data on discrete adsorption rates suggested that lysozyme was adsorbing as multi-layer aggregates on to the ZnSe prism, and showed faster adsorptiondesorption patterns on an uncoated compared to a TiO2-coated ZnSe IR prism. A novel phosphate-modified TiO2 coating material for ZnSe IR prism was prepared as adsorbate which increased the negative charge on the TiO2 surface via P-O-Ti coordinated linkages, increasing the initial rate of lysozyme adsorption. Enhanced adsorption of lysozyme was achieved by increasing both the solution pH and NaCl concentration. Maximum adsorption occurred at pH 11 which corresponded to the protein’s isoelectric pH. Conclusions: ATR-IR spectroscopy has proved to be a useful method to study surface adsorption of antibacterial agents such as lysozyme for further explorations into approaches to control biofouled surfaces.

Highly Active and Stable Large Catalase Isolated from a Hydrocarbon Degrading Aspergillus terreus MTCC 6324

A hydrocarbon degrading Aspergillus terreus MTCC 6324 produces a high level of extremely active and stable cellular large catalase (CAT) during growth on n-hexadecane to combat the oxidative stress caused by the hydrocarbon degrading metabolic machinery inside the cell. A 160-fold purification with specific activity of around 66 × 105 U mg−1 protein was achieved. The native protein molecular mass was 368 ± 5 kDa with subunit molecular mass of nearly 90 kDa, which indicates that the native CAT protein is a homotetramer. The isoelectric pH (pI) of the purified CAT was 4.2. BLAST aligned peptide mass fragments of CAT protein showed its highest similarity with the catalase B protein from other fungal sources. CAT was active in a broad range of pH 4 to 12 and temperature 25°C to 90°C. The catalytic efficiency (Kcat/Km) of 4.7 × 108 M−1 s−1 within the studied substrate range and alkaline pH stability (half-life, t1/2 at pH 12~15 months) of CAT are considerably higher than most of the extensively studied catalases from different sources. The storage stability (t1/2) of CAT at physiological pH 7.5 and 4°C was nearly 30 months. The haem was identified as haem b by electrospray ionization tandem mass spectroscopy (ESI-MS/MS).

Polymorphism and Bioinformatics Analysis of Growth Differentiation Factor 9 Gene in Lori Sheep

Growth differentiation factor 9 (GDF9) is a fecundity major gene affecting prolificacy in sheep. In the present study, genetic variation of a 380-bp fragment in GDF9 gene exon 1 was investigated in 100 Lori ewes. Single-strand conformational polymorphism (SSCP) and DNA sequencing methods were used to detect single nucleotide polymorphism (SNP) of the studied fragment. A SNP (g.306G>A), known as G1 mutation, with two genotypes (GG and AG) was found in two different SSCP patterns of GDF9 gene exon 1, deducing an amino acid (AA) exchange (p.Arg87His). Frequencies of the AG and GG genotypes were 37.65% and 62.35%, respectively. Also, the estimated allelic frequencies for the A and G alleles were 18.825% and 81.175%, respectively. The observed nucleotide sequences were subjected to alignment analysis and it was found that the studied fragment had more than 99.7% similarity with some sequences reported for other breeds of sheep. Two different secondary and 3D protein structures were predicted for A and G alleles. Moreover, the A and G alleles had different isoelectric pH values (8.7 and 9, respectively). The observed genotypes tended to have a significant association with litter size (P<0.10) where average litter size of GG ewes was slightly (20%) higher than for AG animals. With respect to the results of the present study, it seems that more studies are needed to evaluate the mutations in other fragments of this gene or other genes in Lori sheep.

The influence of individual clay minerals on formation damage of reservoir sandstones: a critical review with some new insights

The influence of individual clay minerals on formation damage of reservoir sandstones is reviewed, mainly through the mechanism of fine particle dispersion and migration leading to the accumulation and blockage of pore throats and significant reduction of permeability. The minerals discussed belong to the smectite, kaolinite, illite and chlorite groups respectively. These minerals usually occur in an aggregate form in reservoir sandstones and the physicochemical properties of these aggregates are reviewed in order to reach a better understanding of the factors that lead to their dispersion in aqueous pore fluids. Particularly significant properties include the surface charge on both basal and edge faces of the clay minerals and how this varies with pH, external surface area of both swelling and non-swelling clays, porosity and pore size distribution in the micro- and meso-pore size range and overall aggregate morphology. For non-swelling clays, and perhaps even for swelling clays, dispersion is thought to be initiated at the micro- or meso-pore level, where the interaction between the pore solution and the charged clay surfaces exposed on adjacent sides of slit- or wedge-shaped pores brings about expansion of the diffuse double electric layer (DDL) and an increase in hydration pressure. Such expansion occurs only in dilute electrolyte solutions in contrast to the effect of concentrated solutions which would shrink the thickness of the DDL and so inhibit dispersion. Stable dispersions are formed, particularly where the solution pH exceeds the isoelectric pH of the mineral, which is often at alkali pH values, so that both basal face and edge surfaces are negatively charged and the particles repel each other. The osmotic swelling of smectitic clays to a gel-like form, so effectively blocking pores in situ, is often invoked as an explanation of formation damage in reservoir sandstones. Such swelling certainly occurs in dilute aqueous solutions under earth surface conditions but it is uncertain that stable smectitic gels could form at the temperatures and pressures associated with deeply buried reservoir sandstones.