Sodium Dodecyl Sulfate-polyacrylamide Gel Research Articles

Cysteine, sodium metabisulfite, and glutathione enhance crosslinking between proteins during high moisture meat analog extrusion processing and may improve the fibrousness of the products.

High moisture meat analog (HMMA) products processed using extrusion have become increasingly popular in the last few years. Because the formation of disulfide bonds is believed to play a critical role in the texturization mechanism, this study aimed to understand how chemical compounds capable of reducing disulfide bonds, specifically cysteine, sodium metabisulfite, and glutathione, affect the texture and the chemical interactions between the proteins. Wheat protein blended with cysteine, sodium metabisulfite, or glutathione at levels of 0, 0.5, 1.0, 2.5, 5.0, and 7.5 g kg-1 was extruded at three different temperatures (115, 140, and 165 °C) using a co-rotating twin-screw extruder. The feed rate (85 g min-1), the moisture content (600 g kg-1), and the screw speed (300 rpm) were kept constant. Unextruded and extruded material was subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis, polymeric protein fractionation, and sulfhydryl group/disulfide bond analysis. Extruded samples were further analyzed for their hardness and their anisotropic index. The inclusion of reductants significantly affected the structure of the obtained extrudates. Although reducing agents had a relatively small impact on the total amount of disulfide bonds, their action significantly enhanced crosslinking between the proteins. At select conditions, samples with high fibrousness were specifically obtained when cysteine or sodium metabisulfite was included at levels of 5.0 g kg-1. In the presence of reducing agents, it is believed that disulfide bonds are split earlier during the process without binding to them, giving the protein strands more time to unravel and align, leading to a better flow behavior and more fibrous products. © 2024 Society of Chemical Industry.

Methanol gel electrophoresis: Separation of human fast and slow myosin light chain 1 and other myofibrillar protein isoforms on a single gel format.

This report describes a novel sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) resolving gel format that consistently yields the electrophoretic separation of the fast and slow isoforms of human sarcomeric myosin light chain 1 (MLC1). The inclusion of methanol as a constituent of the resolving gel impacted the electrophoretic mobility of proteins across a broad range of molecular masses. There was greater separation of the fast and slow isoforms of human MLC1, as well as separation and high resolution of fast and slow isoforms of the three myosin heavy chain isoforms that are expressed in human skeletal muscle on the same gel format. Furthermore, the same resolving gel format substantially altered the electrophoretic mobility of at least one isoform of tropomyosin in human striated muscle. It is possible that the inclusion of methanol in SDS-PAGE resolving gels could improve the separation of other proteins that are expressed in muscle and in other tissues and cell types.

Molecular Characterization of Methicillin-resistant Staphylococcus aureus (MRSA) Isolates from Ruminants

Background: Methicillin-resistant Staphylococcus aureus (MRSA) infection is one of the leading causes of infections in animals as well as human beings and is associated with significant morbidity, mortality, length of stay and cost burden. Methods: In this study, 725 samples of nasal swabs and milk were collected randomly from cattle, buffalo, sheep and goats and these samples were inoculated on Mannitol salt agar mixed with Oxacillin Resistance Selective Supplement for the molecular characterization of MRSA isolates through sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and polymerase chain reaction (PCR) test. Result: Out of 725 samples, 171 were found positive for Oxacillin resistant S. aureus. The SDS-PAGE showed different bands of molecular weight 13, 17, 20, 24, 26, 28, 33, 36, 39, 43, 47, 59, 64, 72, 86, 97 and 121 kDa. An amplified mec A DNA fragment (137) of 533 base pairs (bp) and PCR product of fem A (133 isolates) of 510 bp were detected in isolates.

Investigation of cytogenetic, electrophoretic, histopathological and biochemical effects of walnut (juglans regia l.) Leaf extract in rats experimentally induced diabetes by streptozotocin

In this study, the effects of Juglans regia L. (JR) leaf extract on histological damage and cytogenetic, electrophoretic, and biochemical parameters in the liver and kidney tissues of diabetic rats were investigated. In the study, 60 male rats (Sprague-Dawley) were separated into six groups. According to sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) data, it was determined that there were increases and decreases in different serum protein expressions because of the treatment of JR leaf extract in the diabetes group. In the kidney tissue of the diabetes group, an increase in volume in the glomeruli and narrowing of the Bowman's space as well as thickening of the walls of tubules were detected. Vacuolization and shedding were observed in the epithelial cells of tubules in the cortical regions in kidney. In diabetic + JR extract groups administered JR leaf extract at doses of 250 mg/kg and 500 mg/kg, serum AST and ALT levels were reduced compared to the diabetic group. Diabetic rats' livers showed spotted necrosis and fibrosis in the portal area, biliary tract proliferation, mild inflammation, increased vascularization, unicellular necrosis in hepatocytes, and sinusoidal dilatation. The JR leaf extract group did not exhibit these problems. JR leaf extract influences reducing hepatotoxic and oxidative damage due to diabetes and increasing the level of antioxidant enzymes. As a result, it was concluded that the application of JR leaf extract may have a protective effect against damage caused by diabetes.

Cold plasma for enhancing covalent conjugation of ovalbumin-gallic acid and its functional properties

The utilization of cold plasma (CP) treatment to promote covalent conjugation of ovalbumin (OVA) and gallic acid (GA), as well as its functionality, were investigated. Results demonstrated that CP significantly enhanced the covalent grafting of OVA and GA. The maximum conjugation of GA, 24.33 ± 2.24 mg/g, was achieved following 45 s of CP treatment. Covalent conjugation between GA and OVA were confirmed through analyses of total sulfhydryl (-SH) group, Fourier transform infrared (FTIR) spectroscopy, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Unfolding of the OVA molecule occurred upon conjugation with GA, as evidenced by multiple spectroscopy analyses. Additionally, conjugation with GA resulted in significant improvements in the antioxidant activity and emulsifying properties of OVA. This study demonstrated that CP is a robust and sustainable technique for promoting the covalent conjugate of polyphenols and proteins, offering a novel approach to enhance the functional properties of proteins.

High internal phase emulsions stabilized by physically modified mung bean protein isolates under different pHs

This research explored the impact of modified mung bean protein isolates (MBPIs) on the physicochemical, rheological, and structural properties of 70% oil-containing high internal phase emulsions (HIPEs). MBPIs (4% protein concentration) were subjected to heating (90 °C for 2 h) or sequential heating/ultrasonication (20 kHz, 120 W for 10 min) at different pHs (2, 7, and 10). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of modified MBPIs confirmed heat treatment at pH 2 hydrolyzed MBPI, unlike MBPIs heated at pH 7 and 10. Sequential heating/ultrasonication significantly reduced particle size, improved solubility and surface hydrophobicity of MBPIs, resulting in smaller droplet size and enhanced gel-like properties of HIPEs. Transmission electron microscopy revealed that sequentially heated/ultrasonicated MBPIs in the oil–water interface existed in a fibrillar or randomly aggregated structure at pH 2, a randomly aggregated structure at pH 7, and a particulate aggregated structure at pH 10. Overall, these structural modifications at varied pH conditions influenced MBPI adsorption at the HIPE droplet interface, impacting rheological features and promoting the potential use of protein-stabilized HIPEs across diverse applications.

Development of Drying Methodology for Intact Whole Buffalo Liver, Its Characterization, Shelf Life, and Evaluation of Palatability as Pet Treat

Globally, large quantity of animal byproducts is generated from the slaughter of food animals, but there is lack of research articles related to drying of these byproducts and its use as pet food. Therefore, this study was conducted with the aim of utilization of intact whole buffalo liver by drying for pet treat, evaluating its shelf life and palatability. The intact liver surface was superficially sliced, and the surface was pierced. Thereafter, the livers were pretreated in 3% sugar and 4% salt solution (1 : 3 w/v) for 3 h followed by microwaving for 4 min and hot air drying at 60°C for 40 h (designated as T2L). The livers which were dried the same as T2L except surface piercing were referred as T1L, whereas the livers dried only using hot air oven were referred as control (CL). The moisture and protein contents of the dried CL and T2L were found to be 28.46% and 14.29% and 43.85% and 52.76%, respectively. Sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS-PAGE) image of T2L revealed the presence of few low as well as high molecular weight protein bands which were absent in CL and T1L indicating a comparatively lower level of protein degradation in T2L. The shelf life of T1L and T2L samples based on microbiological and lipid oxidation analyses was found to be more than 60 days at 25 and 4°C. Palatability studies using dogs showed that all dried samples were highly palatable. Thus, it could be concluded that intact buffalo liver could be dried using surface slicing, with/without piercing followed by salt and sugar pretreatment, 4 min microwaving, and hot air drying at 60°C for 40 h. Future study should focus on the sensory properties such as aroma, texture, and flavor and sensory analysis of the dried liver by human.

Development of PCR-based markers for identification of wheat HMW glutenin Glu-1Bx and Glu-1By alleles

BackgroundIn common wheat (Triticum aestivum L.), allelic variations in the high-molecular-weight glutenin subunits Glu-B1 locus have important effects on grain end-use quality. The Glu-B1 locus consists of two tightly linked genes encoding x- and y-type subunits that exhibit highly variable frequencies. However, studies on the discriminating markers of the alleles that have been reported are limited. Here, we developed 11 agarose gel-based PCR markers for detecting Glu-1Bx and Glu-1By alleles.ResultsBy integrating the newly developed markers with previously published PCR markers, nine Glu-1Bx locus alleles (Glu-1Bx6, Glu-1Bx7, Glu-1Bx7*, Glu-1Bx7OE, Glu-1Bx13, Glu-1Bx14(−), Glu-1Bx14(+)/Bx20, and Glu-1Bx17) and seven Glu-1By locus alleles (Glu-1By8, Glu-1By8*, Glu-1By9, Glu-1By15/By20, Glu-1By16, and Glu-1By18) were distinguished in 25 wheat cultivars. Glu-1Bx6, Glu-1Bx13, Glu-1Bx14(+)/Bx20, Glu-1By16, and Glu-1By18 were distinguished using the newly developed PCR markers. Additionally, the Glu-1Bx13 and Glu-1Bx14(+)/Bx20 were distinguished by insertions and deletions in their promoter regions. The Glu-1Bx6, Glu-1Bx7, Glu-1By9, Glu-1Bx14(−), and Glu-1By15/By20 alleles were distinguished by using insertions and deletions in the gene-coding region. Glu-1By13, Glu-1By16, and Glu-1By18 were dominantly identified in the gene-coding region. We also developed a marker to distinguish between the two Glu-1Bx14 alleles. However, the Glu-1Bx14(+) + Glu-1By15 and Glu-1Bx20 + Glu-1By20 allele combinations could not be distinguished using PCR markers. The high-molecular-weight glutenin subunits of wheat varieties were analyzed by ultra-performance liquid chromatography and sodium dodecyl sulfate–polyacrylamide gel electrophoresis, and the findings were compared with the results of PCR analysis.ConclusionsSeven Glu-1Bx and four Glu-1By allele detection markers were developed to detect nine Glu-1Bx and seven Glu-1By locus alleles, respectively. Integrating previously reported markers and 11 newly developed PCR markers improves allelic identification of the Glu-B1 locus and facilitates more effective analysis of Glu-B1 alleles molecular variations, which may improve the end-use quality of wheat.

Effect of limited proteolysis and CaCl2 on the rheology, microstructure and in vitro digestibility of pea protein-carboxymethyl cellulose mixed gel

Limited proteolysis, CaCl2 and carboxymethyl cellulose (CMC) have individually demonstrated ability to increase the gel strength of laboratory-extracted plant proteins. However, the syneresis effects of their combination on the gelling capacity of commercial plant protein remains unclear. This was investigated by measuring the rheological property, microstructure and protein–protein interactions of gels formed from Alcalase hydrolyzed or intact pea proteins in the presence of 0.1 % CMC and 0–25 mM CaCl2. Sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed the molecular weight of pea protein in the mixture were < 15 kDa after hydrolysis. The hydrolysates showed higher intrinsic fluorescence intensity and lower surface hydrophobicity than the intact proteins. Rheology showed that the storage modulus (G') of hydrolyzed pea protein (PPH)-based gels sightly decreased compared to those of native proteins. 5–15 mM CaCl2 increased the G’ for both PP and PPH-based gels and decreased the strain in the creep-recovery test. Scanning electron microscopy (SEM) showed the presence of smaller protein aggregates in the PPH-based gels compared to PP gels and the gel network became denser, and more compact and heterogenous in the presence of 15 and 25 mM CaCl2. The gel dissociation assay revealed that hydrophobic interactions and hydrogen bonds were the dominant forces to maintain the gel structure. In vitro digestion showed that the soluble protein content in PPH-based gels was 10 ∼ 30 % higher compared to those of the PP counterpart. CaCl2 addition reduced protein digestibility with a concentration dependent behavior. The results obtained show contrasting effects of limited proteolysis and CaCl2 on the gelling capacity and digestibility of commercial pea proteins. These findings offer practical guidelines for developing pea protein-based food products with a balanced texture and protein nutrition through formulation and enzymatic pre-treatment.

Enzymatic and Algebraic Methodology to Determine the Contents of Kunitz and Bowman-Birk Inhibitors and Their Contributions to Total Trypsin or Chymotrypsin Inhibition in Soybeans.

Soybeans are the number one source of plant proteins for food and feed, but the natural presence of protein protease inhibitors (PIs), namely, the Kunitz trypsin inhibitor (KTI) and the Bowman-Birk inhibitor (BBI), exerts antinutritional effects. This communication describes a new methodology for simultaneously quantitating all parameters of PIs in soybeans. It consists of seven steps and featured enzymatically measuring trypsin and chymotrypsin inhibitory activities, respectively, and subsequently determining the contents of reactive KTI and BBI and the contributions of each toward total PI mass and total trypsin or chymotrypsin inhibition by solving a proposed system of linear equations with two variables (C = dB + eK and T = xB + yK). This enzymatic and algebraic (EA) methodology was based on differential inhibitions of KTI and BBI toward trypsin and chymotrypsin and validated by applications to a series of mixtures of purified KTI and BBI, two KTI-null and two conventional soybeans, and by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The EA methodology allowed calculations of PI composition and the contributions of individual inhibitors toward total inhibition with ease. It was first found that although BBI constituted only about 30% of the total PI mass in conventional raw soybeans, it contributed about 80% toward total chymotrypsin inhibitor activity and about 45% toward trypsin inhibitor activity. Therefore, BBI caused more total protease inhibitions than those of KTI. Furthermore, the so-called KTI-null soybean mutants still contained measurable KTI content and thus should be named KTI-low soybeans.

Isolation and characterization of rabies monoclonal antibody charge variants.

Current postexposure prophylaxis of rabies includes vaccines, human rabies immunoglobulin (RIG), equine RIG, and recombinant monoclonal antibodies (mAb). In the manufacturing of rabies recombinant mAb, charge variants are the most common source of heterogeneity. Charge variants of rabies mAb were isolated by salt gradient cation exchange chromatography (CEX) to separate acidic and basic and main charge variants. Separated variants were further extensively characterized using orthogonal analytical techniques, which include secondary and tertiary structure determination by far and near ultraviolet circular dichroism spectroscopy. Charge and size heterogeneity were evaluated using CEX, isoelectric focusing (IEF), capillary-IEF, size exclusion chromatography, sodium dodecyl sulfate polyacrylamide gel electrophoresis, and western blotting. Antigen binding affinity was assessed by enzyme linked immuno-sorbent assay and rapid florescence foci inhibition test. Results from structural and physicochemical characterizations concluded that charge variants are formed due to posttranslational modification demonstrating that the charge heterogeneity, these charge variants did neither show any considerable physicochemical change nor affect its biological function. This study shows that charge variants are effective components of mAb and there is no need of deliberate removal, until biological functions of rabies mAb will get affected.

Composition of high-molecular-weight glutenin subunits and gluten quality in wheat lines with alien genetic material

Background. High-molecular-weight glutenin subunits (HMW-GSs) make the greatest contribution to the formation of baking properties in bread wheat (Triticum aestivum L.). Glutenin polymorphism of bread wheat relatives is significantly richer than in cultivated varieties. The objective of this work was to identify the HMW-GS composition and assess the gluten quality of bread wheat lines with introgressions of alien genetic material.Materials and methods. We studied the parental varieties of spring bread wheat, accessions of the tetraploid and hexaploid Triticum L. species, and 19 introgressive lines produced with their participation. Glutenins were separated using sodium dodecyl sulfate polyacrylamide gel electrophoresis and HMW-GSs were identified using the Payne nomenclature system. Gluten quality was determined in accordance with GOST 13586.1-68 (the 2017–2019 and 2021–2022 growing seasons). Data processing was performed using the Statistica 10.0 and MS Excel software packages.Results and conclusion. HMW-GSs uncharacteristic of T. aestivum cultivars were identified in the studied accessions of T. dicoccoides (Körn. ex Aschers. et Graebn.) Schweinf., T. spelta L., and T. kiharae Dorof. et Migusch. These HMW-GSs are of interest for enriching the wheat gene pool. HMW-GSs of related species were found in 10 out of 19 introgressive lines. A five-year observation period revealed that wheat relatives on average significantly exceeded common wheat cultivars in gluten quality, and introgressive lines did not differ significantly from the parental genotypes. Lines with high rheological properties of gluten had, as a rule, HMW-GSs of related species in their composition.

Heat Treatment and Homogenization Influence the Gastric Digestion of Bovine Milk Protein in Growing Pigs as an Adult Human Model

BackgroundBovine milk processing influences the structure of the curd formed during gastric digestion, which may alter gastric protein hydrolysis and impact amino acid (AA) release into the small intestine. ObjectivesThis study aimed to determine the influence of heat treatment and homogenization on the gastric protein digestion and AA emptying of bovine milk. MethodsNine-wk-old pigs (n = 144) consumed either raw, pasteurized nonhomogenized (PNH), pasteurized homogenized (PH), or ultra-high-temperature homogenized (UHT) bovine milk for 10 d. On day 11, fasted pigs received the milk treatment (500 mL) before gastric contents were collected at 0, 20, 60, 120, 180, and 300 min postprandially. The apparent degree of gastric protein hydrolysis (based on the release of free amino groups), apparent gastric disappearance of individual proteins [based on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) gel band intensity], and the gastric emptying of digested protein and AA were determined. ResultsDuring the first 60 min, the rate of apparent gastric protein hydrolysis was fastest in pigs fed UHT milk (0.29%/min compared with on average 0.07%/min in pigs fed raw, PNH, and PH milk). Differences in the apparent degree of gastric protein hydrolysis and emptying were reflected in the rate of digested protein entering the small intestine. The AA gastric emptying half-time was generally shorter in pigs fed PH and UHT milk than in pigs fed raw and PNH milk. For example, the gastric release of total essential AA was >2-fold faster (P < 0.01) in pigs fed PH or UHT milk than that in pigs fed raw or PNH milk (i.e., homogenized compared with nonhomogenized milk). ConclusionsHeat treatment and homogenization increased the apparent gastric degree of protein hydrolysis and the release of digested protein into the small intestine. However, the rate of AA entering the small intestine was mainly increased by homogenization.

Loss and gain of ceftazidime-avibactam susceptibility in a non-carbapenemase-producing K1-ST23 hypervirulent Klebsiella pneumoniae

ABSTRACT Objectives This study aimed at revealing the underlying mechanisms of the loss and gain of ceftazidime-avibactam susceptibility in a non-carbapenemase-producing hypervirulent Klebsiella pneumoniae (hvKp). Methods Here we longitudinally recovered 3 non-carbapenemase-producing K1-ST23 hvKp strains at a one-month interval (KP29105, KP29499 and KP30086) from an elderly male. Antimicrobial susceptibility testing, whole genome sequencing, transcriptomic sequencing, gene cloning, plasmid conjugation, quantitative real-time PCR (qRT-PCR), and SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis) were conducted. Results Among the 3 hvKp strains, KP29105 was resistant to the third- and fourth-generation cephalosporins, KP29499 acquired resistance to both ceftazidime-avibactam and carbapenems, while KP30086 restored its susceptibility to ceftazidime-avibactam, imipenem and meropenem but retained low-level resistance to ertapenem. KP29105 and KP29499 carried plasmid-encoded genes bla CTX-M-15 and bla CTX-M-71, respectively, but KP30086 lost both. Cloning of gene bla CTX-M-71 and conjugation experiment of bla CTX-M-71-carrying plasmid showed that the transformant and transconjugant were susceptible to ceftazidime-avibactam but had a more than 8-fold increase in MICs. Supplementation with an outer membrane permeabilizer could reduce the MIC of ceftazidime-avibactam by 32 folds, indicating that porins play a key role in ceftazidime-avibactam resistance. The OmpK35 of the 3 isolates was not expressed, and the OmpK36 of KP29499 and KP30086 had a novel amino acid substitution (L359R). SDS-PAGE and qRT-PCR showed that the expression of porin OmpK36 of KP29499 and KP30086 was significantly down-regulated compared with KP29105. Conclusions In summary, we reported the rare ceftazidime-avibactam resistance in a non-carbapenemase-producing hvKp strain. Resistance plasmid carrying bla CTX-M-71 and mutated OmpK36 had a synergetic effect on the resistance.

Effect of Keratin Waste on Poly(ε-Caprolactone) Films: Structural Characterization, Thermal Properties, and Keratinocytes Viability and Proliferation Studies

Keratin extracted (KE) from chicken feathers was used for the production of composite films comprising poly(ε-caprolactone) (PCL) and keratin (PCL/KE films). The process involved the extraction of keratin from chicken feathers using a 0.1 M NaOH solution, followed by characterization via sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The PCL was synthesized through the ring-opening polymerization (ROP) of ε-caprolactone (ԑ-CL) with Sn(Oct)2 as a catalyst. Films were prepared via solvent casting, including pure PCL films and those enriched with different weight percentages of KE (10%, 15%, 25%, and 30%). The films were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TG), and scanning electron microscopy (SEM). SEM analysis revealed a more uniform incorporation of KE within the PCL matrix in the case of the 15% keratin-enriched film (PCL/KE15) as compared to other keratin percentages. The thermal analysis showed a positive influence of keratin on the thermal stability of the films. Keratinocytes viability and proliferation tests on the PCL/KE15 film demonstrated compatibility with cells. Collectively, these results hold relevance for potential biomedical applications of PCL/KE films.

Predicting Myosin Heavy Chain Isoform Through Muscle Fiber Length in Older Adults

Myosin heavy chain (MHC) isoforms directly impact muscle cellular contractile characteristics and are closely associated with other cellular functions (substrate metabolism, calcium handling, etc.). As such, MHC isoform has come to define muscle “fiber type” (MHC I = slow/oxidative and MHC II = fast/glycolytic). Due to the heterogeneity of MHC isoforms expressed within human skeletal muscle tissue, it is essential to determine MHC isoform to allow proper interpretation of tissue level outcomes that may arise from variations within or between fiber types. A priori estimation of fiber type would be a useful tool for ensuring even distribution of fiber type when considering cellular assays in which MHC isoform can only be determined after the fact. Based on the assumption that fibers of various MHC isoform would differently resist mechanical strain, we’ve demonstrated that MHC I fibers can be distinguished from MHC II fibers based on the ratio of fiber to bundle length (degree of stretch) during mechanical dissection. However, our approach used samples from healthy young adults and has not been tested in tissue from older adults, where cellular stiffness is likely elevated. Therefore, our objective is to test our ability to predict MHC isoform in older adults. We hypothesize that muscle fiber strain following dissection will predict MHC isoform in older adults. Methods: Muscle biopsies from the vastus lateralis muscle were obtained from two older adults (one male, one female). A total of 129 muscle fibers were dissected and measured. Fibers were then stored individually and MHC isoform was subsequently identified via sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-Page). Receiver Operating Characteristics (ROC) and confusion matrix were used to assess the predictive capacity for fiber stretch on activation as an index of fiber type. Data: An ROC area under curve (AUC) of 0.634 which indicates that there is a relatively low predictive capacity. Summary: This study aimed to test the feasibility of an approach for predicting muscle fiber type through changes in fiber length upon mechanical dissection. Established in young adults, this study tested samples obtained from older adults to explore the potential effects of age. Preliminary data show that muscle fiber length can predict muscle fiber type in older adults, though the accuracy may be limited when compared with the same approach in younger adults. This lack of accuracy may be attributed to the increase in stiffness that occurs with age, limiting the capacity for strain and thus fiber type variability. A new threshold may need to be determined to increase the accuracy of fiber type prediction. Conclusion: Preliminary data shows that fiber length can provide a prediction for MHC isoform in older adults. NIH National Institute on Aging (1R21AG077125-01A1) and Achievement Rewards for College Scientists (ARCS) Oregon. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effects of high-intensity ultrasound on physicochemical and gel properties of myofibrillar proteins from the bay scallop (Argopecten irradians)

Myofibrillar proteins (MPs) have a notable impact on the firmness and flexibility of gel-based products. Therefore, enhancing the gelation and emulsification properties of scallop MPs is of paramount significance for producing high-quality scallop surimi products. In this study, we investigated the effects of high-intensity ultrasound on the physicochemical and gelation properties of MPs from bay scallops (Argopecten irradians). The carbonyl content of MPs significantly increased with an increase in ultrasound power (150, 350, and 550 W), indicating ultrasound-induced MP oxidation. Meanwhile, high-intensity ultrasound treatment (550 W) enhanced the emulsifying capacity and the short-term stability of MPs (up to 72.05 m2/g and 153.05 min, respectively). As the ultrasound power increased, the disulfide bond content and surface hydrophobicity of MPs exhibited a notable increase, indicating conformational changes in MPs. Moreover, in the secondary structure of MPs, the α-helix content significantly decreased, whereas the β-sheet content increased, thereby suggesting the ultrasound-induced stretching and flexibility of MP molecules. Sodium-dodecyl sulfate–polyacrylamide gel electrophoresis and scanning electron microscopy analysis further elucidated that high-intensity ultrasound induced MP oxidation, leading to modification of amino acid side chains, intra- and intermolecular cross-linking, and MP aggregation. Consequently, high-intensity ultrasound treatment was found to augment the viscoelasticity, gel strength, and water-holding capacity of MP gels, because ultrasound treatment facilitated the formation of a stable network structure in protein gels. Thus, this study offers theoretical insights into the functional modification of bay scallop MPs and the processing of its surimi products.

Structural and functional properties of whey protein isolate-inulin conjugates prepared with ultrasound or wet heating method.

Whey protein isolate (WPI) generally represents poor functional properties such as thermal stability, emulsifying activity and antioxidant activity near its isoelectric point or high temperatures, which limit its application in the food industry. The preparation of WPI-polysaccharide covalent conjugates based on Maillard reaction is a promising method to improve the physical and chemical stability and functional properties of WPI. In this research, WPI-inulin conjugates were prepared through wet heating method and ultrasound method and their structural and functional properties were examined. In conjugates, the free amino acid content was reduced, the high molecular bands were emerged at sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), new C-N bonds were formed in Fourier-transform infrared (FTIR) spectroscopy, and fluorescence intensity was reduced compared with WPI. Furthermore, the result of circular dichroism (CD) spectroscopy also showed that the secondary structure of conjugates was changed. Conjugates with ultrasound treatment had better structural properties compared with those prepared by wet heating treatment. The functional properties such as thermal stability, emulsifying activity index (EAI), emulsion stability (ES) and antioxidant activity of conjugates with wet heating treatment were significantly improved compared with WPI. The EAI and ES of conjugates with ultrasound treatment were the highest, but the thermal stability and antioxidant activity were only close to that of the conjugates with wet heating treatment for 2 h. This study revealed that WPI-inulin conjugates prepared with ultrasound or wet heating method not only changed the structural characteristics of WPI but also could promote its functional properties including thermal stability, EAI, ES and antioxidant activity. © 2024 Society of Chemical Industry.

Analytical Methods and Effects of Bioactive Peptides Derived from Animal Products: A Mini-Review.

Peptides with bioactive effects are being researched for various purposes. However, there is a lack of overall research on pork-derived peptides. In this study, we reviewed the process of obtaining bioactive peptides, available analytical methods, and the study of bioactive peptides derived from pork. Pepsin and trypsin, two representative protein digestive enzymes in the body, are hydrolyzed by other cofactors to produce peptides. Bicinchoninic acid assay, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, chromatography, and in vitro digestion simulation systems are utilized to analyze bioactive peptides for protein digestibility and molecular weight distribution. Pork-derived peptides mainly exhibit antioxidant and antihypertensive activities. The antioxidant activity of bioactive peptides increases the accessibility of amino acid residues by disrupting the three-dimensional structure of proteins, affecting free radical scavenging, reactive oxygen species inactivation, and metal ion chelating. In addition, the antihypertensive activity decreases angiotensin II production by inhibiting angiotensin converting enzyme and suppresses blood pressure by blocking the AT1 receptor. Pork-derived bioactive peptides, primarily obtained using papain and pepsin, exhibit significant antioxidant and antihypertensive activities, with most having low molecular weights below 1 kDa. This study may aid in the future development of bioactive peptides and serve as a valuable reference for pork-derived peptides.

Small ubiquitin-like modifier-tag and modified protein purification significantly increase the quality and quantity of recombinant African swine fever virus p30 protein.

African swine fever (ASF) is a highly virulent and contagious viral disease caused by the ASF virus (ASFV). It has a significant impact on swine production throughout the world, while existing vaccines and specific treatments remain ineffective. ASFV p30 is a potent antigenic protein that induces protective antibodies immediately after infection; however, most recombinant p30 is insoluble. This study aimed to improve the solubility, yield, and purity of recombinant p30 by tagging it with a small ubiquitin-like modifier (SUMO) and modifying the protein purification process. SUMO fused with ASFV p30 (SUMO-p30) and p30 alone were cloned and expressed in Escherichia coli. SUMO-p30 and p30 solubility and expression levels were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Protein purification was modified by combining ammonium sulfate precipitation method with affinity chromatography. In addition, large-scale production of all versions of p30 were compared using SDS-PAGE and western blotting, and the purified p30 was used to develop the indirect enzyme-linked immunosorbent assay (ELISA). The solubility and expression levels of SUMO-p30 were dramatically enhanced compared with that of p30. Modification of the purification process significantly increased purified and soluble SUMO-p30 and p30 yields by 6.59 and 1.02 μg/mL, respectively. Large-scale production confirmed that this procedure increased the quantity of recombinant p30 while maintaining protein purity and immunogenicity. The p30-based indirect ELISA was able to discriminate between positive and negative serum samples with statistically significant differences in mean optical density 450 values (p < 0.001). This study demonstrates the enhancement of solubility, purity, and yield of ASFV p30 expressed in E.coli by SUMO fusion tagging and combining ammonium sulfate precipitation with affinity chromatography for protein purification. These positive effects were sustained in large-scale production. Cleavage and removal of hexahistidine-SUMO tag from the fusion protein by protease may not be suitable when handling a large amount of the protein. However, the SUMO-fused p30 retained strong immunoreactivity to convalescent swine serum, indicating its application in immunization and diagnostic purposes. The expression and purification procedures in this study could be applied to increase solubility, quality, and quantity of other recombinant proteins as well.