Vicilin Protein Research Articles

Dynamic properties of the layers of cupin-1.1 aggregates at the air/water interface

Spread layers of amorphous aggregates of the structural domain of plant protein vicilin, cupin-1.1, at the water – air interface were studied by the surface tensiometry, dilational surface rheology, Brewster angle and atomic force microscopy. The layer properties differed strongly from the results for the layers of previously studied proteins. The dependency of the dynamic elasticity of the layer on surface pressure had two local maxima with the second peak being four times higher than the first one. In the region of the first maximum the obtained results are similar to those for dispersions of polymer microgels with a hairy corona. At the beginning of surface compression separate threads of the corona are stretched along the surface and the surface elasticity increases. The further compression results in the formation of loops and tails leading to a decrease of the elasticity. The second local maximum of the dynamic surface elasticity is presumably caused by the interactions of the rigid cores of the aggregates leading finally to the formation of multilayer structures at high surface pressures. In this case, the surface elasticity starts to decrease as a result of the segment exchange between different layers at the interface.

Improved extraction and modification of plant protein from desi chickpea variety using green technology

This study shows the effect of the ultrasound-assisted extraction (UAE) method in desi chickpea protein isolate at 50 % and 100 % amplitude i.e., 200 W – 24 kHz at various processing times. The changes occur to the functional properties of desi chickpea protein compared to the conventional extraction method. The UAE approach yielded more protein than the conventional method. The solubility also increased in the UAE method at 15 min at 200 W. The highest solubility was 91.1 %, and the lowest was in the conventional extraction method, 85.5 %. In emulsion, oil holding capacity and stability, foaming capacity, and stability were also increased according to the increase in the ultrasound than the conventional extraction method. The water-holding capacity was decreased in the UAE method. The WHC in the US-assisted extracted protein was 1.528 g, and in conventional method, 1.614 g. The digestibility in US-treated protein shows better results than the control. In FT-IR, there was a variation in the nitro and cyclic alkane compounds in the US-treated sample. According to the results from SEM, zeta, particle size, and SDS PAGE, desi chickpea protein isolate powder showed smooth surface, decrease in zeta potential along with the particle size and legumin, vicilin protein fractions are detected respectively.

Synergistic effect of pH-shift and controlled heating on improving foaming properties of pea vicilin and its adsorption behavior at the air-water interface

In this study, the impact of pH-shift (PV-pH), controlled heating (PV–H), high intensity ultrasound (PV–U), and their combinations (PV-pH-H, PV-pH-U, PV-H-U) on the structural, foaming, and surface behavior at the air-water interface of the modified pea vicilin (PV) protein fraction were comprehensively evaluated. Results showed that the foaming capacity (FC) of samples treated by either PV-pH or PV-H was significantly increased (105.26%, 105.64%) as compared to the control (73.53%). This synergistic effect was observed with the combination of pH-shift and controlled heating (PV-pH-H), which drastically improved the FC of the modified PV (153.97%). Interestingly, ultrasound treatment exhibited the least effect on the FC of PV, no matter whether it was applied individually or combined with other treatments. The improved FC of PV was mainly attributed to newly formed soluble aggregates, the transition of β-sheet to α-helix, and increased surface hydrophobicity (H0), allowing PV to exist in a more flexible structure. The dynamic adsorption behaviors of the modified PV at the air-water interface indicated that its improvement in FC was also associated with the high surface pressure with short lag time. In addition, the modified PVs formed a strong elastic interfacial film through densely packed protein molecule as evidenced by E-π slop (>1). This study demonstrated that a simple pH shift combined with controlled heating technique could be applied to improve the foaming properties of PV.

Germination and ultrafiltration modify the composition and functional properties of hemp seed protein isolates

Ultrafiltration was investigated for its ability to alter the composition of hemp seed protein isolates (HSPI) and modify its functional properties. Hemp seeds that were germinated for 0, 1, 3, and 5 days underwent alkaline extraction and protein isolation by isoelectric precipitation (IP) or ultrafiltration (UF). UF processing with a 100 nm membrane resulted in the loss of off-color pigments as well as vicilin proteins and small peptides ∼9 kDa, which changed the physicochemical properties and functionality of HSPI. We found that HSPIs from UF were lighter in color and higher in protein purity than isolates from IP, but lower in solubility. Germination paired with UF increased the water holding capacity by 2.3 times, from 1.06 to 2.46 g water/g isolate, while oil holding capacity was unaffected by germination and UF. UF resulted in protein isolates with decreased foaming capacity and increased gelation concentration compared to IP, but 5-day germinated HSPIs had statistically unchanged emulsifying activity indexes between the two processing methods. Germination and UF are thus presented as clean-label processing techniques to modify the composition and functionality of HSPIs.

β-Conglutins' Unique Mobile Arm Is a Key Structural Domain Involved in Molecular Nutraceutical Properties of Narrow-Leafed Lupin (Lupinus angustifolius L.).

Narrow-leafed lupin (NLL; Lupinus angustifolius L.) has multiple nutraceutical properties that may result from unique structural features of β-conglutin proteins, such as the mobile arm at the N-terminal, a structural domain rich in α-helices. A similar domain has not been found in other vicilin proteins of legume species. We used affinity chromatography to purify recombinant complete and truncated (without the mobile arm domain, tβ5 and tβ7) forms of NLL β5 and β7 conglutin proteins. We then used biochemical and molecular biology techniques in ex vivo and in vitro systems to evaluate their anti-inflammatory activity and antioxidant capacity. The complete β5 and β7 conglutin proteins decreased pro-inflammatory mediator levels (e.g., nitric oxide), mRNA expression levels (iNOS, TNFα, IL-1β), and the protein levels of pro-inflammatory cytokine TNF-α, interleukins (IL-1β, IL-2, IL-6, IL-8, IL-12, IL-17, IL-27), and other mediators (INFγ, MOP, S-TNF-R1/-R2, and TWEAK), and exerted a regulatory oxidative balance effect in cells as demonstrated in glutathione, catalase, and superoxide dismutase assays. The truncated tβ5 and tβ7 conglutin proteins did not have these molecular effects. These results suggest that β5 and β7 conglutins have potential as functional food components due to their anti-inflammatory and oxidative cell state regulatory properties, and that the mobile arm of NLL β-conglutin proteins is a key domain in the development of nutraceutical properties, making NLL β5 and β7 excellent innovative candidates as functional foods.

Comparisons of Structure, Stability, and IgE Cross-Reactivity among Cashew, Pistachio, Walnut, and Peanut Vicilin-Buried Peptides

Vicilin-buried peptides (VBPs) are derived from the N-terminal leader-sequence (LS) of vicilin proteins and are receiving increasing attention as novel food allergens. Characterizing the VBPs from peanuts and tree nuts may help understand comorbidity and cross-reactivity despite a distant evolutionary origin.

Water Use Efficiency, Spectral Phenotyping and Protein Composition of Two Chickpea Genotypes Grown in Mediterranean Environments under Different Water and Nitrogen Supply

Chickpea is a drought-tolerant crop and an important source of protein, relevant to its beneficial effects. The aim of this study was to assess the response to agronomic management, including water and nitrogen supply, of crop physiological and agronomic traits in relation to water use efficiency and grain protein composition. Two varieties, Pascià and Sultano, were grown at two different sites in South Italy under rainfed and irrigated conditions, with and without starter nitrogen fertilization. Crop physiological assessment was carried out by hyperspectral phenotyping at flowering and during grain filling. Increases in grain yield and grain size in relation to water supply were observed for water use up to about 400 mm. Water use efficiency increased under starter nitrogen fertilization, and Pascià showed the highest values (4.8 kg mm−1). The highest correlations of the vegetation indexes with the agronomic traits were observed in the later growth stage, especially for the optimized soil-adjusted vegetation index (OSAVI); furthermore, grain filling rate showed a strong relationship with photochemical reflectance index (PRI). Experimental factors mainly influenced protein composition rather than protein content. In particular, the 7s vicilin protein fraction showed a negative correlation with grain yield and water use, while lectin showed an opposite response. Both fractions are of interest for consumer’s health because of their allergenic and antinutritional properties, respectively. Data from spectral phenotyping will be useful for digital farming applications, in order to assess crop physiological status in modern agricultural systems.

Biologically Synthesized Peptides Show Remarkable Inhibition Activity against Angiotensin-Converting Enzyme: A Promising Approach for Peptide Development against Autoimmune Diseases.

Angiotensin-converting enzyme (ACE) regulates several biological functions besides its vital role in immune functions. ACE is elevated in immune cells in inflammatory diseases including atherosclerosis, granuloma, chronic kidney disease, and also autoimmune diseases, like multiple sclerosis, rheumatoid arthritis, and type I diabetes. No significant information prevails in the literature regarding the isolation, identification, and profiling of potential ACE inhibitory peptides. In the present study, indigenous crop varieties like seeds (peanut, corn, oat, sunflower, chickpea, parsley, cottonseed, papaya, sesame, and flaxseed) were used to evaluate their ACE inhibition activity. Variables including hydrolysis time, enzyme-to-substrate ratio (E/S), pH, and temperature were standardized to acquire the most suitable and optimum ACE inhibition activity. Seeds of cotton, chickpea, and peanuts displayed remarkably maximum ACE inhibition activity than other plants. The study disclosed that maximum ACE inhibitory activity (86%) was evaluated from cottonseed at pH 8.0, temperature of 45°C, hydrolysis time of 2 hrs, and enzyme to the substrate (E/S) ratio of 1 : 5 followed by peanuts (76%) and chickpea (55%). SDS-PAGE confirmed that vicilin protein is present in cottonseed and peanut seed while cruciferin and napin proteins are present in chickpeas. LC-MS/MS analysis disclosed potential novel peptides in hydrolyzed cottonseed that can be ascribed as potential ACE inhibitors which have never been reported and studied earlier. The current study further showed that cottonseed peptides due to their promising ACE inhibitory activity can be a valuable source in the field of ACE inhibitor development.

The Aggregates of Vicilin Protein Are Found in the Roots and Nodules of Pisum sativum L.

Amyloids are unbranched protein fibrils with a characteristic spatial structure and unusual features including high resistance to detergent or protease treatment. Numerous investigations of amyloids are of the top interest due to the increasing incidence of amyloid-associated disorders, for instance, Alzheimer's disease, Parkinson's disease, type II diabetes, and also due to functional roles of amyloids in prokaryotes and eukaryotes. Previously, for the first time, we have found that 47 kDa Vicilin, belonging to the 7S globulin storage protein group, form amyloids in plant seeds (Antonets et al., PLOS Biology, 2020). In this work, using previously obtained polyclonal antibody, we studied the production of the Vicilin protein in various parts of the garden pea (Pisum sativum L.) plants. According to the results of western blot hybridization, Vicilin was found in all observed organs of the pea (leaves, tendrils, shoots, roots and nodules), but its amount was much higher in the roots and nodules, and there was also found an aggregated fraction of this protein. In vivo, histological analysis of pea plant organs cryosections showed the presence of Vicilin in roots as well as in nodules, which, combined with western blot results allows us to presume that all or some of it is in an aggregate form. These findings let us hypothesize that aggregated Vicilin is involved in the supra-organismal interactions between P. sativum L. and symbiotic bacteria.

Optimization of Cowpea Dry Grain Yield through the Stimulation of the RNA Synthetic Activity of NADH-Glutamate Dehydrogenase

Several potentially practical biochemical processes in plant systems still remain hidden, especially the NADH-glutamate dehydrogenase (GDH) synthesis of nongenetic code-based RNA that optimizes crop nutritious yield by degrading superfluous genetic code-based RNA. In continued characterization of the biochemistry of cowpea grain yield, GDH was purified by electrophoresis from seeds of cowpea treated with solutions of stoichiometric mixes of mineral salts. The GDH was made to synthesize RNAs in the amination (α-KG/NADH/) and then in the deamination (L-Glu/NAD+) direction. The initial product RNAs were captured and sequenced. The grand challenge was to discover the specific molecular roles of the redox enzyme in the optimization of cowpea grain yields. In the amination direction, the GDH hexamers synthesized plus-RNA, but in the deamination direction, they synthesized minus-RNA. The plus-RNAs and minus-RNAs were homologous to about the same numbers of different mRNAs encoding the key enzymes that regulate photosynthesis; saccharide biochemistry and glycolysis; phenylpropanoid biosynthesis; nodulation nitrogen fixing processes; dehydrin drought and glutathione environmental stress resistance processes; purine, pyrimidine, DNA, RNA and essential amino acid biosynthesis; storage protein vicilin accumulation; isoflavone earliness of cowpea maturity; peroxidase synthesis of lignin and sequestration of CO2 to enrich soil organic carbon contents; triglyceride physiology in the biosynthesis of bioactive compounds that render cowpea resistant to insects and fungi; etc., all of which constitute the GDH chemical pathways for discrimination of biochemical, physiological, metabolic, genetic reactions; and optimization of cowpea dry grain yields. Each stoichiometric mix of mineral salts produced optimally yielding biochemical variant of purple hull cowpea; the K + K + K mix was spectacular because it increased the grain yield to 7598 kg from the 3644 kg·ha-1 in the control cowpea. Optimized nutritious staple crop yield buttresses food security. The synthesis of plus-RNA in amination and minus-RNA in deamination is an economic tactical plan in biochemistry for the selection of superfluous mRNAs that would be degraded to assure the survival of cowpea growing under unfavorable environmental conditions.

Composition and some functional properties of Bambara groundnuts vicilin fraction

Bambara groundnut is a drought tolerant pulse grain and an alternative source of protein. In this study, Bambara vicilin (7S) protein fraction was extracted and characterised in comparison to the storage protein. The proline content of vicilin fraction (4.3 g/100 g protein) was almost four times that of the storage protein. Fluorescence and hydrophobicity data suggested a less folded structure for the vicilin fraction when compared to the storage protein. Gel electrophoresis indicated three major polypeptides (50, 70 and 80 kDa) in the vicilin fraction with the presence of disulfide bond(s) in one of the strands. In contrast to the storage protein, which had <40% protein solubility at pH 2–9, vicilin had a significantly (p < 0.05) higher solubility with a minimum of 50% at pH 5 and maximum of 82% at pH 3. Emulsifying stability of the proteins significantly differed (p < 0.05) at pH 7. Foaming capacity of the vicilin fraction was significantly (p < 0.05) higher than that of the storage protein at pH 3, 7, and 9. It could be concluded that Bambara vicilin fraction could serve as a potential ingredient in the formulation of food products at acidic pH.

Narrow‐leafed lupin (Lupinus angustifolius L.) β‐conglutin: A multifunctional family of proteins with roles in plant defence, human health benefits, and potential uses as functional food

AbstractLupinus angustifolius or narrow‐leafed lupin (NLL) is an important Pulse world‐wide and an outstanding alternative source of high quality proteins. NLL β‐conglutin (vicilin or 7S acid globulin), a multigene family of proteins, is the main representative protein in NLL seeds exhibiting multifunctional properties and benefits recently discovered. These functions may result from specific structural features of NLL β‐conglutins in comparison with most legume vicilin proteins. From the agricultural side, NLL β‐conglutin proteins (1a) exert antifungal properties promoting enhanced plant resistance to necrotrophic oomycete pathogens and (1b) displaying functional interplay between storage protein mobilization and seed oxidative metabolism as a functional regulatory and signalling crossroad for the control of physiological underlying processes of the seed dormancy breakage and release, during germination, and seedling growth. NLL β‐conglutins benefits go beyond nutritional properties because displayed nutraceutical functions make them an outstanding source of innovative ingredients for functional food. They have antioxidant activity and anti‐inflammatory properties, which are able to improve inflammatory‐related diseases such as type 2 diabetes through (a) regulation of insulin signalling pathway, (b) improving insulin sensitivity, (c) facilitating glucose uptake by cells, (d) together with their capacity for balancing the oxidative homeostasis, metabolic, and signalling pathways (e) while reducing reactive oxygen specie production and increase cellular oxidative defence capacity. Interestingly, NLL β‐conglutins also display anti‐nutritional properties as proteins capable to elicit allergic responses in sensitized individuals. This review outlines newly discovered knowledge of the narrow‐leafed lupin β‐conglutin proteins drawing on information gained from structure‐functional properties, agriculture benefits, as well as nutraceutics and molecular allergy point of views.

Binding of benzoic acid and anions within the cupin domains of the vicilin protein canavalin from jack bean (Canavalia ensiformis): Crystal structures

X-ray intensities extending to 1.4 Å resolution were collected on the P63 hexagonal crystal form of canavalin, and extended to 1.9 Å for the orthorhombic C2221 crystals. Structure determination of a new crystal form of canavalin having space group P212121 is reported as well. Both the N and C terminal cupin domains contained identifiable ligands. For hexagonal crystals, in the cavity of the C terminal cupin, a molecule of benzoic acid was found, bound through carboxyl oxygens to Histidine 297, asparagine 284 and Arginine 376. The benzene ring was immersed in a cluster of at least 8 hydrophobic amino acid side chains. The N terminal cupin contained a molecule of citrate. Benzoic acid was also found to be present in the C terminal cupins of in the C2221 and P212121 crystal forms. In rhombohedral crystals, the C terminal cupin domain appeared to be occupied by a phosphate ion, but this was ambiguous. In cubic crystals, both domains were vacant. The N terminal cupin domains of canavalin in the P212121 and rhombohedral crystals were also vacant, but the N terminal cupin domain of the C2221 crystals contained a ligand whose identity is uncertain, but which has been modeled as HEPES buffer. A possible physiological role for the ligands and their complexes with canavalin is considered.

DIA (Data Independent Acquisition) proteomic based study on maize filling-kernel stage drought stress-responsive proteins and metabolic pathways

Drought is one of the most severe environmental stressors hampering maize (Zea mays L.) production worldwide. Therefore, revealing the molecular mechanisms underpinning maize drought tolerance is critical for guiding drought resistance breeding and ensuring global food security. Herein, we performed a data-independent acquisition (DIA) proteomics-based comparative analysis of the proteome responses of two contrasting maize hybrids (drought-tolerant NongDan 476 and drought-sensitive ZhongXin 978) exposed to 12 days of water-deficit (drought) treatment at the kernel filling stage. Resultantly, our DIA-based analysis approach identified a total of 826 differentially abundant proteins (DAPs), among which 7 DAPs were specifically accumulated in tolerant genotype ND 476 under drought treatment conditions. Moreover, our results showed that there were significant differences in drought stress responses between the two hybrids at the proteomic level. Predominantly, our analysis revealed that maize drought tolerance is attributed to some key proteins such as chaperones, DNA replication related enzymes, vicilin and ABA-responsive RAB17 protein, participating in several metabolic networks including starch and sucrose metabolism, terpenoid backbone biosynthesis, cyanoamino acid metabolism and carbon metabolism pathways. Our findings provide further insights into the drought stress tolerance mechanisms in maize at the grain filling period, in addition to useful reference data for maize drought resistance breeding.

Extraction, gelation and microstructure of Bambara groundnut vicilins

Nowadays there is a growing interest in exploiting new sources of plant proteins as functional ingredients in food products. In recent years, Bambara groundnut (Vigna subterranea (L.) Verdc.) [BGN] has been explored as such a potential plant protein source, as a means of value-addition to this leguminous crop. To elucidate on the macroscopic functionality of BGN protein isolates, the focus of our study was on the extraction and characterisation of the vicilin protein fraction as the known major storage protein present in legume seeds. BGN vicilin had a high protein content (91%) and formed the largest component in relation to the other protein fractions. Together with molecular weight profiles obtained with gel electrophoresis and size-exclusion chromatography coupled with light scattering, the purity of vicilin and its presence as the predominant protein fraction in BGN black-eye seeds were confirmed. The isoelectric point (pH 5.3), solubility profile (highest solubility 86% at NaCl concentrations above 200 mM) and thermal denaturation temperature (92 °C) of BGN vicilin correspond to the range reported for other legume vicilins. Furthermore, the gelation behaviour of BGN vicilin gels was investigated using dynamic oscillatory measurements. These data were further analysed with scaling models, which revealed that fractal scaling was best suited for description of the BGN vicilin gel networks. The gel microstructures were visualised with confocal laser scanning and scanning electron microscopy.

Vicilin-A major storage protein of mungbean exhibits antioxidative potential, antiproliferative effects and ACE inhibitory activity.

Enzymatic hydrolysates of different food proteins demonstrate health benefits. Search for diet related food protein hydrolysates is therefore of interest within the scope of functional foods. Mungbean is one of the popular foods in India because of rich protein source. In this study, mungbean vicilin protein (MBVP) was enzymatically hydrolysed by alcalase and trypsin under optimal conditions. We have studied the antioxidant, antiproliferative and angiotensin-converting enzyme (ACE) inhibitory activities of mungbean vicilin protein hydrolysate (MBVPH) vis-a-vis alcalase-generated mungbean vicilin protein hydrolysate (AMBVPH) and trypsin-generated mungbean vicilin protein hydrolysate (TMBVPH). The results showed that MBVPH exhibited higher antioxidant potential, ACE inhibitory and antiproliferative activities than MBVP. The alcalase treated hydrolysate displayed highest ACE inhibitory activity with IC50 value of 0.32 mg protein/ml. The MBVP showed significant antiproliferative activity against both MCF-7 and MDA-MB-231 breast cancer cells at the doses between 0.2–1.0 mg/ml. The data suggested that MBVPH can be utilized as physiologically active functional foods with sufficient antihypertensive activity. The results indicate that mungbean can be utilized as a rich resource of functional foods.

The Vicilin protein (Vigna radiata L.) of mung bean as a functional food

PurposeThe hypocholesterolemic activity of legume vicilins and the structural homology among mung bean, soybean and adzuki bean vicilins (8S) suggest that this protein may play a role in lipid metabolism. Thus, in the present study, the authors aim to isolate the mung bean vicilin and assess its in vitro effect on 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMG CoAr), the enzyme responsible for endogenous cholesterol synthesis.Design/methodology/approachChromatographic and electrophoretic characterization identified the molecular mass and polypeptide composition of mung bean vicilin. The hydrolysate of this globulin was obtained by sequential hydrolysis with pepsin-pancreatin and the fragments were characterized by molecular filtration, SDS PAGE and HPLC.FindingsThe molecular mass of vicilin was estimated as 158.23 at ± 10 kDa and SDS-PAGE revealed that the 8S globulin protein comprises four bands corresponding to polypeptides of 61, 48, 29 and 26 kDa. Fractions 10, 12, 14, 22 and 32 of the eluate from Sephadex G-25 exhibited significant inhibition of HMG CoAr.Originality/valueThe correspondence of the chromatographic profile of the peptide fractions with hypocholesterolemic activity suggests that the composition and chemical structure of these peptides are essential to their physiological effectiveness. The beneficial effects of mung bean vicilin identified in this study will support the characterization of this protein as a functional compound.

Biochemical fate of vicilin storage protein during fermentation and drying of cocoa beans

Key cocoa-specific aroma precursors are generated during the fermentation of cocoa beans via the proteolysis of the vicilin-like globulin. Previous studies had shown that degradation of this particular 566 amino acid-long storage protein leads to three distinct subunits with different molecular masses. Although oligopeptides generated from the proteolysis of vicilin-like globulin have been studied previously, changes occurring to vicilin at different stages of fermentation have not yet been explored in detail. The aim of this study was to investigate the fate of vicilin protein from the non-fermented stage up to the dried cocoa beans. Our results showed a remarkable shift in the electrophoretic mobility of vicilin towards higher pI during the onset of fermentation. The pI-shifted subunit was found susceptible to further degradation into a lower-molecular-weight vicilin subunit. The observed pI shift correlated with, but did not depend on protein phosphorylation. Glycosylation of some but not all vicilin subunits occurred at different stages of the fermentation process. Peptides generated from vicilin throughout fermentation were analyzed by UHPLC-ESI-MS/MS revealing an initial increase and subsequent decrease in the diversity of peptides with an increasing degree of fermentation. We furthermore describe the rate of degradation of different vicilin subunits. The detected diversity and dynamics of vicilin peptides will help to define biochemical markers of distinct steps of the fermentation process.

Effect of genotype and environment on the surface characteristics and functionality of air-classified faba bean protein concentrates

The overall goal of this research was to examine the effect of genotype and environment on the ratio of legumin to vicilin proteins (L/V), the surface characteristics and the functionality of air-classified faba bean protein concentrates. Seeds of five faba bean (Vicia faba) genotypes (CDC-Fatima, Taboar, SSNS-1, FB9-4 and FB18-20) grown in 2012 at two field plot locations, Melita and Morden (Manitoba, Canada), were used. L/V ratios ranged from 3.76 to 5.40 depending on the genotype and the environment, as only the effect of environment was found to be significant (p < 0.05). The L/V ratio for concentrates produced from seeds grown in Melita was greater than those grown in Morden. The effect of genotype and the interaction effect between genotype and environment on the surface charge were also found to be significant (p < 0.05). The protein concentrates’ surface charge ranged between −19.4 and −31.8 mV (at pH 7.0). The effect of environment on the interfacial tension was significant (p < 0.001), as the values for protein concentrates were found to be lower for those produced from seeds grown in Melita (7.9 mN/m) than those grown in Morden (10.2 mN/m). No significant effects were found for the surface tension and foaming capacity in response to either genotype or environment. The foam stability was influenced by the environment and by the interaction between genotype and environment (p < 0.05). The effects of genotype and environment on the emulsion stability, oil-holding capacity and water hydration capacity were insignificant. As for the protein concentrates’ solubility, the effect of genotype and the interaction between genotype and environment were significant, with values of solubility ranging between 82.3 and 88.0 %.

Antimicrobial Activity of a Cys-Rich Peptide Derived from a &amp;lt;i&amp;gt;Centrosema virginianum&amp;lt;/i&amp;gt; Vicilin

Many antimicrobial peptides (AMPs) have been identified in plants. These peptides are highly divergent at the primary sequence level and vary in their hierarchical structures. Some common biochemical features include the ability to form disulfide bonds, tandemly repeated amino acid sequences and a net charge at pH 7. Unusual Cysteine containing repeats has been identified in several plant seed storage proteins that may act as AMPs. We identified a Cys repeat within a vicilin (seed storage protein) of a wild legume, Centrosema virginianum. Cleavage of the vicilin protein during germination would generate a vicilin derived Cys peptide (VDCP). We investigated the antimicrobial properties of this VDCP and compared its efficacy as an antimicrobial agent to VDCPs from other species. We developed transgenic tobacco plants that expressed cloned sequences encoding the Cysteine repeat unit from C. virginianum, Theobroma cacao and Gossypium hirsutum. Extracts from fully expanded leaves were tested for antimicrobial activity against a fungal pathogen, Botrytis cinerea. The Cys motif from C. virginianum was also expressed in two E. coli cell lines (reducing or oxidizing cytoplasm) and peptide fusion protein fractions were tested for antimicrobial activity against a battery of fungal strains. The unique Cysteine repeat single unit from C. virginianum exhibited antimicrobial properties greater than or equal to the antimicrobial activity associated with expression of the multiple Cys-repeat VDCPs from G. hirsutum or T. cacao in transgenic tobacco. When expressed in bacteria, a C. virginianum VDCP fusion protein exhibited antifungal activity against 3 of the 4 fungi tested. Although the primary role of seed storage proteins is to provide a pool of amino acids and nitrogen for germinating seeds and developing plantlets, it is likely that seed storage protein proteolytic products also provide beneficial antimicrobial properties during germination and young plantlet development.