Major Functional Properties Research Articles

Changes in the structure and functional properties of lactoferrin with different iron saturations before and after simulated high‐temperature short‐time heat treatments

The major functional properties of lactoferrin (LF) samples before and after high‐temperature short‐time (HTST: 72°C/15 s, 85°C/15 s and 95°C/15 s) treatment were investigated by turbiscan stability index, circular dichroism spectroscopy and other methods. The lower the LF iron saturation, the higher the iron binding, antibacterial and antioxidant capacity, but more unstable after HTST treatment. 40%‐LF had the best physical and structural stability, but lower antibacterial and antioxidant capacity. Upon HTST treatment, the physical stability, antibacterial and antioxidant properties of LF samples were significantly reduced, especially for 95°C/15 s. Of note, LF with iron saturation higher than 15% was resistant to HTST treatment.

Polypeptide composition of major oilseed proteins and functional properties of extracted protein products: A concise review

AbstractOilseeds are grown mainly for their oil content but the residues (meals) that remain after defatting are excellent sources of plant protein ingredients. However, to serve as useful ingredients, the extracted proteins must meet industry expectations in terms of functional performance. Protein functionality is influenced by structural conformation, amino acid composition, type of polypeptides, presence of non‐protein materials (carbohydrates, lipids, and polyphenols), which in turn can be modified by the extraction method. Defatted oilseed meals are extracted mostly through the pH shift method, which involves alkaline solubilization followed by acid‐induced protein precipitation at the isoelectric point. A less popular method is called the protein micellar mass whereby the oilseed meal proteins are extracted with a NaCl solution, which is later diluted to reduce the ionic strength to a level where the proteins are no longer soluble and hence precipitate. A third method utilizes carbohydrases and phytases to first digest non‐protein materials from the oilseed meal into smaller units that are then removed by membrane ultrafiltration to leave behind a protein‐rich extract. These methods produce mainly two types of isolated oilseed proteins, concentrates (60%–89% protein content) and isolates (≥90% protein content), which can differ in terms of their protein conformation, solubility, and functionality as food ingredients. Therefore, this review provides an overview of the extraction and isolation as well as structural and functional properties of soybean, peanut, canola, hemp seed, sunflower, and sesame seed proteins.

Black Bean: Composition, Protein Extraction and Functional Properties

Black beans play an essential part in the human diet due to their high protein content and nutritional value. Black beans are high in energy, dietary fiber, protein, minerals, and vitamins, and they have well-balanced essential amino acid profiles. The production of black bean protein concentrates or isolates is of growing interest to food industry because of their functional properties and ability to improve the nutritional quality of food products. Various procedures are used to obtain protein concentrates / isolates with varying properties. Because of desired functional features such as gelling and emulsifying properties, black bean proteins have grown in popularity and could be presented as a potential supplement in a wide range of food applications. This review provides an overview of the chemical composition of black bean, current and emerging techniques for producing their protein concentrates / isolates, and major functional properties.

Principles of metabolome conservation in animals

Metabolite levels shape cellular physiology and disease susceptibility, yet the general principles governing metabolome evolution are largely unknown. Here, we introduce a measure of conservation of individual metabolite levels among related species. By analyzing multispecies tissue metabolome datasets in phylogenetically diverse mammals and fruit flies, we show that conservation varies extensively across metabolites. Three major functional properties, metabolite abundance, essentiality, and association with human diseases predict conservation, highlighting a striking parallel between the evolutionary forces driving metabolome and protein sequence conservation. Metabolic network simulations recapitulated these general patterns and revealed that abundant metabolites are highly conserved due to their strong coupling to key metabolic fluxes in the network. Finally, we show that biomarkers of metabolic diseases can be distinguished from other metabolites simply based on evolutionary conservation, without requiring any prior clinical knowledge. Overall, this study uncovers simple rules that govern metabolic evolution in animals and implies that most tissue metabolome differences between species are permitted, rather than favored by natural selection. More broadly, our work paves the way toward using evolutionary information to identify biomarkers, as well as to detect pathogenic metabolome alterations in individual patients.

In Vivo Incorporation of Photoproteins into GroEL Chaperonin Retaining Major Structural and Functional Properties.

The incorporation of photoproteins into proteins of interest allows the study of either their localization or intermolecular interactions in the cell. Here we demonstrate the possibility of in vivo incorporating the photoprotein Aequorea victoria enhanced green fluorescent protein (EGFP) or Gaussia princeps luciferase (GLuc) into the tetradecameric quaternary structure of GroEL chaperonin and describe some physicochemical properties of the labeled chaperonin. Using size-exclusion and affinity chromatography, electrophoresis, fluorescent and electron transmission microscopy (ETM), small-angle X-ray scattering (SAXS), and bioluminescence resonance energy transfer (BRET), we show the following: (i) The GroEL14-EGFP is evenly distributed within normally divided E. coli cells, while gigantic undivided cells are characterized by the uneven distribution of the labeled GroEL14 which is mainly localized close to the cellular periplasm; (ii) EGFP and likely GLuc are located within the inner cavity of one of the two GroEL chaperonin rings and do not essentially influence the protein oligomeric structure; (iii) GroEL14 containing either EGFP or GLuc is capable of interacting with non-native proteins and the cochaperonin GroES.

Targeting Astrocyte Signaling Alleviates Cerebrovascular and Synaptic Function Deficits in a Diet-Based Mouse Model of Small Cerebral Vessel Disease.

Despite the indispensable role that astrocytes play in the neurovascular unit, few studies have investigated the functional impact of astrocyte signaling in cognitive decline and dementia related to vascular pathology. Diet-mediated induction of hyperhomocysteinemia (HHcy) recapitulates numerous features of vascular contributions to cognitive impairment and dementia (VCID). Here, we used astrocyte targeting approaches to evaluate astrocyte Ca2+ dysregulation and the impact of aberrant astrocyte signaling on cerebrovascular dysfunction and synapse impairment in male and female HHcy diet mice. Two-photon imaging conducted in fully awake mice revealed activity-dependent Ca2+ dysregulation in barrel cortex astrocytes under HHcy. Stimulation of contralateral whiskers elicited larger Ca2+ transients in individual astrocytes of HHcy diet mice compared with control diet mice. However, evoked Ca2+ signaling across astrocyte networks was impaired in HHcy mice. HHcy also was associated with increased activation of the Ca2+/calcineurin-dependent transcription factor NFAT4, which has been linked previously to the reactive astrocyte phenotype and synapse dysfunction in amyloid and brain injury models. Targeting the NFAT inhibitor VIVIT to astrocytes, using adeno-associated virus vectors, led to reduced GFAP promoter activity in HHcy diet mice and improved functional hyperemia in arterioles and capillaries. VIVIT expression in astrocytes also preserved CA1 synaptic function and improved spontaneous alternation performance on the Y maze. Together, the results demonstrate that aberrant astrocyte signaling can impair the major functional properties of the neurovascular unit (i.e., cerebral vessel regulation and synaptic regulation) and may therefore represent a promising drug target for treating VCID and possibly Alzheimer's disease and other related dementias.SIGNIFICANCE STATEMENT The impact of reactive astrocytes in Alzheimer's disease and related dementias is poorly understood. Here, we evaluated Ca2+ responses and signaling in barrel cortex astrocytes of mice fed with a B-vitamin deficient diet that induces hyperhomocysteinemia (HHcy), cerebral vessel disease, and cognitive decline. Multiphoton imaging in awake mice with HHcy revealed augmented Ca2+ responses in individual astrocytes, but impaired signaling across astrocyte networks. Stimulation-evoked arteriole dilation and elevated red blood cell velocity in capillaries were also impaired in cortex of awake HHcy mice. Astrocyte-specific inhibition of the Ca2+-dependent transcription factor, NFAT, normalized cerebrovascular function in HHcy mice, improved synaptic properties in brain slices, and stabilized cognition. Results suggest that astrocytes are a mechanism and possible therapeutic target for vascular-related dementia.

An overview of the functional properties of egg white proteins and their application in the food industry

Egg white proteins (EWPs), in addition to their nutritional values, possess excellent functional properties that facilitate their use in the food industry. This review collates the published information concerning the major functional properties of EWPs such as gelling, foaming, and emulsifying. Gelation of EWPs has several applications in various food products such as puddings and desserts. Foaming is an important element in the manufacture of the foods such as cakes, bread, meringues, and cookies. However, the application of EWPs as an emulsifier in food products is limited, and thus, various techniques and methods for improving the emulsifying ability of these proteins have been investigated. The effect of various parameters on the functional properties of EWPs and possible correlations between structure and function, with a focus on practical performance in food systems, are discussed in this paper. These findings can lead to enriching the research systems on the functional properties of EWPs and providing information for the development of new EWPs -derived/enriched food products. • Environmental conditions change hydrophilic/hydrophobic ratio of egg white proteins. • Heat treatments potentially denature egg white proteins (EWPs) and change their structure. • Emulsifying stability of egg white proteins under neutral and alkaline conditions is poor. • Electrostatic and hydrophobic interactions are important during gel formation of EWPs. • EWPs have considerable applications in foods such as meringues and cake batters.

Asynchronous glutamate release is enhanced in low release efficacy synapses and dispersed across the active zone

The balance between fast synchronous and delayed asynchronous release of neurotransmitters has a major role in defining computational properties of neuronal synapses and regulation of neuronal network activity. However, how it is tuned at the single synapse level remains poorly understood. Here, using the fluorescent glutamate sensor SF-iGluSnFR, we image quantal vesicular release in tens to hundreds of individual synaptic outputs from single pyramidal cells with 4 millisecond temporal and 75 nm spatial resolution. We find that the ratio between synchronous and asynchronous synaptic vesicle exocytosis varies extensively among synapses supplied by the same axon, and that the synchronicity of release is reduced at low release probability synapses. We further demonstrate that asynchronous exocytosis sites are more widely distributed within the release area than synchronous sites. Together, our results reveal a universal relationship between the two major functional properties of synapses – the timing and the overall efficacy of neurotransmitter release.

Cryo-electron Microscopy Imaging of Alzheimer's Amyloid-beta 42 Oligomer Displayed on a Functionally and Structurally Relevant Scaffold.

Amyloid‐β peptide (Aβ) oligomers are pathogenic species of amyloid aggregates in Alzheimer's disease. Like certain protein toxins, Aβ oligomers permeabilize cellular membranes, presumably through a pore formation mechanism. Owing to their structural and stoichiometric heterogeneity, the structure of these pores remains to be characterized. We studied a functional Aβ42‐pore equivalent, created by fusing Aβ42 to the oligomerizing, soluble domain of the α‐hemolysin (αHL) toxin. Our data reveal Aβ42‐αHL oligomers to share major structural, functional, and biological properties with wild‐type Aβ42‐pores. Single‐particle cryo‐EM analysis of Aβ42‐αHL oligomers (with an overall 3.3 Å resolution) reveals the Aβ42‐pore region to be intrinsically flexible. The Aβ42‐αHL oligomers will allow many of the features of the wild‐type amyloid oligomers to be studied that cannot be otherwise, and may be a highly specific antigen for the development of immuno‐base diagnostics and therapies.

Cryo‐electron Microscopy Imaging of Alzheimer's Amyloid‐beta 42 Oligomer Displayed on a Functionally and Structurally Relevant Scaffold

AbstractAmyloid‐β peptide (Aβ) oligomers are pathogenic species of amyloid aggregates in Alzheimer's disease. Like certain protein toxins, Aβ oligomers permeabilize cellular membranes, presumably through a pore formation mechanism. Owing to their structural and stoichiometric heterogeneity, the structure of these pores remains to be characterized. We studied a functional Aβ42‐pore equivalent, created by fusing Aβ42 to the oligomerizing, soluble domain of the α‐hemolysin (αHL) toxin. Our data reveal Aβ42‐αHL oligomers to share major structural, functional, and biological properties with wild‐type Aβ42‐pores. Single‐particle cryo‐EM analysis of Aβ42‐αHL oligomers (with an overall 3.3 Å resolution) reveals the Aβ42‐pore region to be intrinsically flexible. The Aβ42‐αHL oligomers will allow many of the features of the wild‐type amyloid oligomers to be studied that cannot be otherwise, and may be a highly specific antigen for the development of immuno‐base diagnostics and therapies.

Multi‐functional magnetic hydrogel: Design strategies and applications

AbstractHydrogel is one of the hottest biomaterials in recent years. Especially, magnetic hydrogels (MHs) prepared by combining unique magnetic nanoparticles (MNPs) with hydrogels have attracted wide attention due to their excellent biocompatibility, mechanical properties, absorbability and rich magnetic properties (magnetocaloric, magnetic resonance imaging and intelligent response, etc.). However, the current literature mainly focuses on the application of MHs, without fully understanding the relationship between the design strategies and applications of each function in MHs. This review highlights six major functional properties of MHs, including mechanical properties, adsorption, magnetocaloric effect, magnetic resonance (MR) imaging, intelligent response and biocompatibility. Principles and design strategies of each performance are thoroughly analyzed. Furthermore, the latest applications of MHs in biomedicine, soft actuators, environmental protection, chemistry and engineering in recent 5 years are introduced from the perspective of each function. In the carefully selected representative cases, the design strategies and application principle of multi‐functional MHs are detailed, respectively. The classical fabrication processing of MHs is summarized. At last, we discuss the unmet needs and potential future challenges in MHs development and highlight its emerging strategies.

Characteristics and Functional Properties of collagen extracted from Nile tilapia (Oreochromis niloticus) skin

: Tilapia skin might be used as a new source of collagen, therefore collagen extracted from Nile tilapia skin can be utilized as food products because of its good functional properties. Two extraction methods were used to obtain acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) from Nile tilapia skin. In this study, collagen was characterized in terms of FT-IR Spectrum, amino acid analysis, SDS-PAGE and Thermal denaturation temperatures (Td). Also, some major functional properties including solubility, oil and water absorption, emulsifying activity and stability, foaming ability, foam stability, and gelation properties were determined. The results showed that the yields of ASC and PSC were 4.30% and 1.84 % (on a wet weight basis), respectively. Amino acid composition analysis indicated that the imino acid content of ASC and PSC were found to be 172.10 and 164.18 residues per 1000 residues, respectively. SDS-PAGE results indicated that ASC and PSC were type I collagen. The FTIR Spectrum confirmed that the presence of a triple-helical structure characteristic of ASC and PSC. The denaturation temperature of ASC and PSC were 26⁰C and 25⁰C respectively. The solubility of ASC and PSC were highly solubilized in the pH range of 2–3. ASC and PSC had good water and oil absorption capacity. Gelation studies revealed that ASC and PSC have good gelation properties. Consequently, Nile tilapia skin could be used as a good source to extract ASC and PSC which can be used to add high value in the food industries.

Lupin protein: Isolation and techno-functional properties, a review

Plant proteins are rapidly becoming more of a prime interest to food manufactures as consumers are shifting away from meat-based diets. Therefore, food manufactures need to incorporate functional plant proteins as ingredients into their products. Lupin has a high protein (~40%) and fibre (~40%) content, is low in starch and gluten free hence, it can have an important role. Despite its nutritional and proven health benefits, lupin is underutilised and still does not play a major role in the human diet. Concentrating its protein and producing lupin protein isolate with suitable properties would make it attractive as a high protein and functional ingredient for food manufacturing.Over the recent years the industry has shown interest in large scale production of lupin protein isolate and improving its techno-functional properties. This paper reviews the literature on different lupin protein isolation techniques and conditions. The impact of protein isolation technique on chemical composition, yield and physiochemical properties including solubility, water holding capacity, molecular weight and particle size distribution, of the resultant protein isolates, are compared and contrasted. Moreover, major functional properties such as viscosity, gelling, emulsification, and thermal properties of the isolated proteins are reviewed.Varied extraction yields and largely different properties and functionalities are achieved for different lupin protein extraction techniques. In the light of the unique composition and nutritional properties of lupin seed and its protein component, future research for improving the protein isolation process for lupin and improving its physical functionalities using innovative technologies are discussed.

The many faces of thyroxine.

Hönes et al. have recently shown that in vivo interference with the apparatus of the nuclear receptor-mediated, gene-driven mechanism of triiodothyronine (T3) actions fails to eliminate all actions of T3. However, the investigators conducting that study provided little information regarding the mechanisms that might be responsible for conferring those implied gene-independent effects. Dratman has long ago suggested a system wherein such gene-free mechanisms might operate. Therefore, since news of that discovery was originally published in 1974, it seems appropriate to describe the progress made since then. We propose that thyroxine and triiodothyronine have many different structural properties that may confer a series of different capabilities on their functions. These conform with our proposal that a series of catecholamine analogs and their conversion to iodothyronamines, allows them to perform many of the functions that previously were attributed to nuclear receptors regulating gene expression. The actions of deiodinases and the differential distribution of iodine substituents are among the critical factors that allow catecholamine analogs to change their effects into ones that either activate their targets or block them. They do this by using two different deiodinases to vary the position of an iodide ion on the diphenylether backbones of thyroxine metabolites. A panoply of these structural features imparts major unique functional properties on the behavior of vertebrates in general and possibly on Homo sapiens in particular.

Physiologically Distributed Loading Patterns Drive the Formation of Zonally Organized Collagen Structures in Tissue-Engineered Meniscus.

The meniscus is a dense fibrocartilage tissue that withstands the complex loads of the knee via a unique organization of collagen fibers. Attempts to condition engineered menisci with compression or tensile loading alone have failed to reproduce complex structure on the microscale or anatomic scale. Here we show that axial loading of anatomically shaped tissue-engineered meniscus constructs produced spatial distributions of local strain similar to those seen in the meniscus when the knee is loaded at full extension. Such loading drove formation of tissue with large organized collagen fibers, levels of mechanical anisotropy, and compressive moduli that match native tissue. Loading accelerated the development of native-sized and aligned circumferential and radial collagen fibers. These loading patterns contained both tensile and compressive components that enhanced the major biochemical and functional properties of the meniscus, with loading significantly improved glycosaminoglycan (GAG) accumulation 200-250%, collagen accumulation 40-55%, equilibrium modulus 1000-1800%, and tensile moduli 500-1200% (radial and circumferential). Furthermore, this study demonstrates local changes in mechanical environment drive heterogeneous tissue development and organization within individual constructs, highlighting the importance of recapitulating native loading environments. Loaded menisci developed cartilage-like tissue with rounded cells, a dense collagen matrix, and increased GAG accumulation in the more compressively loaded horns, and fibrous collagen-rich tissue in the more tensile loaded outer 2/3, similar to native menisci. Loaded constructs reached a level of organization not seen in any previous engineered menisci and demonstrate great promise as meniscal replacements.

Experimental investigation of effect of roller burnishing process parameters on surface roughness and surface hardness of C40E steel

Surface finish and dimensional accuracy are ever in demand because of strong influence of these characteristics on major functional properties like friction, fatigue strength, wear resistance, load carrying capacity, and corrosion resistance of any materials. In the present work the effect of burnishing process parameters like burnishing condition, burnishing speed, feed, depth of penetration, number of passes is investigated on the surface roughness and hardness of C40E steel. Taguchi design of experiment is used for present experimentation. Taguchi's L18 mixed orthogonal array is used for optimisation of input parameters and analysis of variance (ANOVA) is employed for concluding vital and fruitful results. Investigation reveals that minimum surface roughness value of .129 µm at wet burnishing condition .557 rpm speed, .06 mm/rev feed, 1.5 mm depth of penetration and double pass of tool and optimised surface hardness 94 HRB at dry burnishing condition, 371 rpm speed, 0.11 mm/rev feed, 1.5 mm depth of penetration and third pass of tool is obtained.

Legume: composition, protein extraction and functional properties. A review

Because of the high protein content and beneficial nutritional value, legumes (lupin, peas, beans, and soybeans) play an important role in human diet. Legumes provide energy, dietary fibre, protein, minerals and vitamins required for human health and endue well-balanced essential amino acid profiles when consumed with cereals and other foods rich in sulphur-containing amino acids and tryptophan. Some antinutritional compounds, found in legumes, can be toxic, unpalatable or indigestible, but their elimination can be achieved by selection of plant genotypes or through post-harvest processing. The production of legume protein concentrates or isolates is of growing interest to food industry because of their functional properties and ability to improve the nutritional quality of food products. For that, various techniques are used to extract protein concentrates / isolates with different features. Legume proteins have gained increasing importance because of desired functional properties, including gelling and emulsifying properties, and could be proposed as a potential supplement in a great number of food applications. This review provides an overview of the chemical composition of legumes (lupin, peas, beans, and soybeans), their antinutritional compounds, current and emerging techniques for producing their protein concentrates / isolates, and major functional properties. DOI: http://dx.doi.org/10.5755/j01.ct.66.1.12355

Wood density, but not leaf hydraulic architecture, is associated with drought tolerance in clones of Coffea canephora

Key message This study highlights that wood density integrates the xylem structural changes and plays a key role in drought tolerance at the intraspecific level in clones of robusta coffee. Robusta coffee (Coffea canephora) is largely cropped in regions where drought stress is the major bottleneck limiting crop yields. We hypothesized that clonal differences in wood density (D w) would be reflected in xylem anatomical differences with associated consequences for hydraulic functioning and ultimately drought tolerance. We assessed the major functional properties of water conduction systems at both the leaf and stem levels in 8-year-old clones of robusta coffee with varying degrees of drought tolerance. The plants were grown outdoors in 24-L pots and either irrigated or subjected to a 4-month water deficit. Upon drought imposition, increased D w, primarily associated with a rearrangement of the fiber matrix and secondarily associated with narrower vessels (although more numerous per cross-sectional area), was correlated with tolerance to hydraulic dysfunctions. Some coordination at the leaf level concerning hydraulic and stomatal anatomical patterns, with stem structural properties, was observed under ample irrigation, but this coordination was decoupled by the imposed drought stress. In conclusion, our data suggest a role for D w in drought tolerance in coffee; however, drought tolerance implies that clones that successfully thrive under low water supply might have compromised fitness under ample irrigation, suggesting a trade-off between D w and the conduction capacity in coffee.

A comprehensive study on enhanced characteristics of modified polylactic acid based versatile biopolymer

Now a days, polylactic acid (PLA) and its derivatives are receiving significant attention due to its versatile applications. The present study provides a deep insight on major structural and functional properties of novel PLA–HA polymer synthesized by incorporating humic acid (HA) in PLA. Topographical features of both pure and modified PLA have been studied using SEM and AFM to analyze their comparative surface microstructures. Incorporation of HA was found to enhance slightly the thermal stability profile of the polymer. However, reduction of Tg, Tm and degree of crystallinity has also been noticed, which in turn resulted in enhanced ductility and higher elongation at break. Moreover, improvement in radical scavenging properties, total available phenolics (0.075 μmole GAE/g film) and water absorption capacity (90.65%) has been observed which essentially suggested introduction as well as enhancement of several utility features, originally absent in pure PLA. The study thus predicts multifaceted applications of PLA–HA polymer, from industrial packaging to fabrication of biomedical devices depending on its superior characteristics as compared to pure PLA.

Transcriptional and posttranscriptional regulations of the HLA-G gene.

HLA-G has a relevant role in immune response regulation. The overall structure of the HLA-G coding region has been maintained during the evolution process, in which most of its variable sites are synonymous mutations or coincide with introns, preserving major functional HLA-G properties. The HLA-G promoter region is different from the classical class I promoters, mainly because (i) it lacks regulatory responsive elements for IFN-γ and NF-κB, (ii) the proximal promoter region (within 200 bases from the first translated ATG) does not mediate transactivation by the principal HLA class I transactivation mechanisms, and (iii) the presence of identified alternative regulatory elements (heat shock, progesterone and hypoxia-responsive elements) and unidentified responsive elements for IL-10, glucocorticoids, and other transcription factors is evident. At least three variable sites in the 3′ untranslated region have been studied that may influence HLA-G expression by modifying mRNA stability or microRNA binding sites, including the 14-base pair insertion/deletion, +3142C/G and +3187A/G polymorphisms. Other polymorphic sites have been described, but there are no functional studies on them. The HLA-G coding region polymorphisms might influence isoform production and at least two null alleles with premature stop codons have been described. We reviewed the structure of the HLA-G promoter region and its implication in transcriptional gene control, the structure of the HLA-G 3′UTR and the major actors of the posttranscriptional gene control, and, finally, the presence of regulatory elements in the coding region.