Polyacrylamide Gel Research Articles

Natural lipopeptide surfactin inhibits insulin aggregation and prevents amyloid-induced cytotoxicity and inflammation

Despite the centennial of the pioneering discovery of insulin, challenges regarding insulin aggregation at the site of repeated injection, as well as during industrial production, storage, and transportation, have cast a gloom over this remarkable success story. Aggregation substantially impacts the quality, potency, and effectiveness of insulin formulation, decreasing bioavailability, intensifying the risk of immunogenicity, and endangering patient health. Herein, the suitability of Bacillus-derived amphiphilic biosurfactant surfactin was demonstrated to evade temperature-induced fibrillation of insulin. Fluorometric assessment employing thioflavin-T and intrinsic tyrosine fluorescence indicated the dose-dependent reduction in insulin unfolding and subsequent formation of fibrils. Decreased thioflavin fluorescence at the plateau stage and about a 79% increase in fibrillation lag time was observed for samples containing an equimolar ratio of insulin to surfactin. Circular dichroism analysis further indicated about a 30% increase in α-helix content in samples containing an equimolar ratio of insulin and surfactin, as compared to controls. The findings were further bolstered by dynamic light scattering, electron microscopic analysis, and native polyacrylamide gel electrophoresis. Molecular docking and simulation studies did not indicate any structural destabilization of insulin with surfactin, having major interactions at the hydrophobic and potential amyloidogenic regions of insulin B-chain: B12-B19 (VEALYLVC) and B23-B27 (GFFYT) through hydrophobic and hydrogen bonds. Notably, an almost 22% increase in cell viability was observed for cells incubated with aggregated insulin containing equimolar concentrations of SFN. Surfactin also subdued insulin amyloid-induced upregulation of the pro-inflammatory genes. Thus, surfactin may be contemplated as an additive in biopharmaceutical formulations to imbue stability and may also be evaluated as anti-amyloid therapeutics for other pathological proteinopathies.

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.

Genotyping and phenotyping of Haptoglobin gene polymorphisms and their correlation with cardiovascular disease and biochemical parameters in Iranian patients with type 2 diabetes mellitus

PurposeWe aimed to examine genotyping and phenotyping of Haptoglobin (Hp) gene polymorphisms and their correlation with cardiovascular disease and biochemical parameters in Iranian patients with type 2 diabetes mellitus. MethodsWe analyzed the phenotype (by polyacrylamide gel electrophoresis and peroxidase labeling), genotype (by extracting DNA), and biochemical characteristics to determine the relationship of Hp polymorphisms with premature CVD and its severity in 148 patients with T2DM, 150 patients with both CVD and T2DM, and 130 healthy controls at Afshar Hospital in Yazd city, Iran. ResultsAfter adjustment for age and gender, the Hp21 and Hp2–2 genotypes and phenotypes were related to an elevated risk of CVD in diabetic participants compared to the control group (OR = 10.35, 95% CI: 3.39–31.59, p = 0001and OR = 9.25, 95% CI: 2.29–28.59, p = 0001, respectively). Such an association was significantly observed in patients with diabetes compared to the control group (OR = 1.06, 95% CI: 0.25–4.20, p = 0.956); however, the frequency of Hp2–1and Hp2–2 genotypes in patients with both diabetes and CVD was not significantly different in comparison with diabetic individuals (OR = 1.65, 95% CI: 0.40–6.83, p = 0.484). After adjusting for age, sex, and disease, we also discovered that the Hp polymorphisms are correlated with low density lipoprotein cholesterol (LDL) and triglyceride (TG) levels. ConclusionBased on what we found, the genotypes and phenotypes of Hp2–2 and Hp2–1 are thought to be risk factors for type 2 diabetes. In addition, these polymorphisms might play an important role in increasing LDL and TG levels.

Biomaterial systems for evaluating the influence of ECM mechanics on anti-fibrotic therapeutic efficacy

Cardiac fibrosis is characterized by excessive accumulation and deposition of ECM proteins. Cardiac fibrosis is commonly implicated in a variety of cardiovascular diseases, including post-myocardial infarction (MI). We have previously developed a dual-delivery nanogel therapeutic to deliver tissue plasminogen activator (tPA) and Y-27632 (a ROCK inhibitor) to address MI-associated coronary artery occlusion and downregulate cell-contractility mediated fibrotic responses. Initial in vitro studies were conducted on glass substrates. The study presented here employs the use of polyacrylamide (PA) gels and microgel thin films to mimic healthy and fibrotic cardiac tissue mechanics. Soft and stiff polyacrylamide substrates or high and low loss tangent microgel thin films were utilized to examine the influence of cell-substrate interactions on dual-loaded nanogel therapeutic efficacy. In the presence of Y-27632 containing nanogels, a reduction of fibrotic marker expression was noted on traditional PA gels mimicking healthy and fibrotic cardiac tissue mechanics. These findings differed on more physiologically relevant microgel thin films, where early treatment with the ROCK inhibitor intensified the fibrotic related responses.

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.

Physical and functional interaction between NHE3 and SGLT2 in the renal proximal tubule of male and female rats

Sodium-glucose cotransporter type 2 (SGLT2) and sodium/hydrogen exchanger-3 (NHE3) serve as the primary renal proximal tubule transporters responsible for the apical uptake of filtered glucose and NaHCO3/NaCl, respectively. Our previous studies demonstrated that chronic treatment with the selective SGLT2 inhibitor empagliflozin reduces NHE3 activity in the proximal tubule. Furthermore, we observed that the non-specific SGLT1/SGLT2 inhibitor, phlorizin, acutely inhibits NHE3 in the absence of luminal glucose, suggesting that the impact of SGLT inhibition on NHE3 may not be attributed to high tubular glucose concentrations. Additionally, our investigations revealed that SGLT2, but not SGLT1, colocalizes with NHE3 in the renal proximal tubule. This study aimed to gain insights into the functional and physical association of NHE3 and SGLT2 in the renal proximal tubule. In vivo microperfusion was conducted in male and female Wistar rats using glucose-free perfusates containing vehicle or empagliflozin (1 μM). Empagliflozin treatment significantly decreased the flow rate of bicarbonate reabsorption (JHCO3−) in both male (2.109±0.091 vs. 1.119±0.096 nmol/cm2∙s) and female rats (1.750±0.037 vs. 1.128±0.062 nmol/cm2∙s), indicating that SGLT2 inhibitors inhibit NHE3 activity through glucose-independent mechanisms. By employing nondenaturant detergents, we utilized blue native polyacrylamide gel electrophoresis (BN-PAGE) to preserve native protein-protein interactions. Double staining with antibodies against specific partner candidates revealed that bands attributed to NHE3, MAP17, PDZK1, and SGLT2 migrate similarly at ~480 kDa in samples from rat renal cortex, as supported by independent experiments. Rigorous controls were implemented to address concerns related to autofluorescence, antibody cross-reactivity, and signal specificity, confirming the validity of our results. Furthermore, complexes involving SGLT2 and NHE3 at an apparent ~480 kDa molecular weight were observed in male and female rats. Unlike SGLT2, SGLT1 bands in BN-PAGE did not overlap with the NHE3 signal, which is consistent with our earlier immunofluorescence experiments. Collectively, our data suggest that NHE3 and SGLT2 are functionally and physically associated with the renal proximal tubule. Future experiments will be undertaken to further characterize the physical association between NHE3 and SGLT2 and to determine whether the inhibition of NHE3 by SGLT2 inhibitors is mediated through the disruption of the NHE3-PDZK1-MAP17-SGLT2 multiprotein complex. Funding: São Paulo Research Foundation (FAPESP). 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.

Ceramides as Mediators of Mitochondrial Dysfunction Driving Kidney Injury

Objective. Perturbations in proximal tubule mitochondrial function and lipid metabolism potentiate acute kidney injury and failed repair. Sphingolipids such as ceramides are recognized as lipotoxic drivers of metabolic dysfunction and cell death. We hypothesized that ceramides drive mitochondrial dysfunction and tubular insult and that lowering ceramides would prevent acute kidney injury in a mouse model of bilateral ischemia reperfusion injury (IRI). Methods. We examined acute effects of ceramide treatment on primary mouse proximal tubule epithelial cell (PTEC) mitochondrial oxygen consumption and mitochondrial supercomplex assembly by Seahorse respirometry and blue native PAGE, respectively. In vivo, we profiled accumulation of ceramides via HPLC-MS/MS in kidney cortex tissue of mice challenged with warm bilateral IRI. We lowered whole-body ceramides via Degs1 inducible global knockout ( Degs1iGKO) in male C57Bl/6J mice prior to challenge with IRI. Clinical, transcriptional, and histopathological renal outcomes were compared to sham-operated and Degs1fl/fl controls 24 hours after kidney reperfusion. Results. Treatment of PTECs with 5-50uM C2-ceramide resulted in acute and dose-dependent decreases in mitochondrial ATP production rates (15-65% decrease from baseline, respectively, p&lt;0.05), as well as disruption of electron transport chain supercomplex structures (i.e., III2+IV and I+III2+IV). In mice, IRI led to a 25% increase in total cortex ceramides (sham: 995±110 vs IRI: 1239±185 pmol lipid/mg protein, p&lt;0.05). Lipid species within the de novo ceramide synthesis pathway were elevated as early as 5 minutes after IRI (e.g., 34% increase in Cer(d18:0/16:0), sham: 2.38±0.27 vs 5 minutes: 3.20±0.81 pmol lipid/mg protein, p&lt;0.05) and continued to accumulate throughout the progression of the AKI up to 24 hours after reperfusion (e.g., 122% increase in Cer(d18:0/16:0), sham: 2.38±0.27 vs 24 hours: 5.29±1.71 pmol lipid/mg protein, p&lt;0.001). Cortex ceramides, particularly deleterious long-chain (e.g., Cer(d18:1/16:0)) species, correlated positively with kidney injury biomarkers (plasma creatinine, Pearson r=0.57; BUN, r=0.74; and cortex expression of Lcn2, r=0.60 , and Havcr1, r=0.62 , p&lt;0.05). Degs1 global knockout decreased cortex ceramide levels by 56% (fl/fl: 995±110 vs KO: 435±174 pmol lipid/mg protein, p&lt;0.001). Degs1iGKO animals had improved cortex histopathology, blood urea nitrogen (fl/fl: 81.02±2.13 vs KO: 49.82±6.34 mg/dL, p &lt;0.001), plasma creatinine (fl/fl: 1.28±0.4 vs KO: 0.32±0.11 mg/dL, p&lt;0.001), and cortex Lcn2 expression (fl/fl: 36.36±21.50 vs KO: 5.31±4.61, p&lt;0.01) following IRI. Conclusions. Renal ceramides are implicated as drivers of kidney injury and mitochondrial dysfunction. Global Degs1 knockout prevented AKI induced by ischemia reperfusion injury. Thus, ceramide-lowering interventions may be an effective strategy to prevent AKI. This work was supported by funding from the National Institutes of Health [R01KD130296 (SAS, WLH), R01DK131609 (SAS), U01CA272529 (SAS), R44DK116450 (SAS), R01DK112826 (WLH), T32DK091317 (RJN), F31DK134088 (RJN)]. 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.

PROBING FIBRINOGEN STRUCTURE: INSIGHTS FROM LIMITED PROTEOLYSIS, PEPTIDES, AND MONOCLONAL ANTIBODIES

Aim. The aim of this study was to analyze the prospects of using antibodyes, peptides and proteases in investigating fibrinogen structure and function. Methods. Polyacrylamide gel electrophoresis, western blotting, turbidimetry, electron microscopy. Results. Since antibodies are specific to a small sequence of amino acid residues, monoclonal antibodies can be used to investigate the importance of a specific site on fibrinogen. For example, using the 1-5A antibodies, which are specific to the C-terminal region of the Aα-chain of fibrinogen, the importance of these regions in the lateral association of protofibrils was established. The study indicates that the presence of various antibodies, each specific to a relatively small region of the fibrinogen molecule, can cause different effects on the functioning of the molecule. It has been demonstrated that synthetic peptide Аα195-205 inhibits the stage of fibrin protofibril formation, while peptide γ69-77 inhibits the lateral association of protofibrils. Another approach in the study of proteins is limited proteolysis. For example, using proteases from the culture medium of B. thuringiensis and the venom of G. halys we separated the functional role of different parts of fibrin(ogen) αС-region in its functioning. Conclusions. Thus, it is important to acknowledge that the described approaches in protein research each have their own advantages and disadvantages, and scientists may choose them based on specific research objectives. Funding. The work was carried out within the framework of scientific research works projects of young scientists of the National Academy of Sciences of Ukraine: «The influence of agonists and antagonists of integrin receptors on the functional effects of platelets» (2023–2024, State registration number 0123U103023).

Study on a Strong Polymer Gel by the Addition of Micron Graphite Oxide Powder and Its Plugging of Fracture.

It is difficult to plug the fracture water channeling of a fractured low-permeability reservoir during water flooding by using the conventional acrylamide polymer gel due to its weak mechanical properties. For this problem, micron graphite powder is added to enhance the comprehensive properties of the acrylamide polymer gel, which can improve the plugging effect of fracture water channeling. The chemical principle of this process is that the hydroxyl and carboxyl groups of the layered micron graphite powder can undergo physicochemical interactions with the amide groups of the polyacrylamide molecule chain. As a rigid structure, the graphite powder can support the flexible skeleton of the original polyacrylamide molecule chain. Through the synergy of the rigid and flexible structures, the viscoelasticity, thermal stability, tensile performance, and plugging ability of the new-type gel can be significantly enhanced. Compared with a single acrylamide gel, after adding 3000 mg/L of micrometer-sized graphite powder, the elastic modulus, the viscous modulus, the phase transition temperature, the breakthrough pressure gradient, the elongation at break, and the tensile stress of the acrylamide gel are all greatly improved. After adding the graphite powder to the polyacrylamide gel, the fracture water channeling can be effectively plugged. The characteristics of the networked water flow channel are obvious during the injected water break through the gel in the fracture. The breakthrough pressure of water flooding is high. The experimental results are an attempt to develop a new gel material for the water plugging of a fractured low-permeability reservoir.

Purification and characterization of glutamate dehydrogenase from rainbow trout (Oncorhynchus mykiss) liver and molecular docking studies.

Glutamate dehydrogenase (GDH) participates in the energy metabolism of proteins and the synthesis of metabolites important for the organism. In this study, GDH enzyme was purified from the liver of rainbow trout (Oncorhynchus mykiss) by 2',5'-ADP Sepharose 4B affinity chromatography in one step. As a result of this purification process, GDH enzyme was purified 171-fold with 5.83U/mg protein-specific activity. The characterization experiments presented that the storage stability of the purified GDH enzyme was determined as -80°C; optimum temperature 40°C; it was determined that the optimum ionic strength was 100mM phosphate buffer and the optimum pH was 8.00. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and PAGE studies showed that the natural molar mass of the purified GDH enzyme was 346.74kDa, and the molar mass of its subunits was 53.71kDa. Km and Vmax values for substrates and coenzymes of GDH enzyme purified from rainbow trout liver were calculated, and the lowest Km value was found in NAD+ (1.86mM) and the highest Vmax value in NH4 + (1.79U/mL). The effects of some metal ions, vitamins, and solvents on the activity of the purified GDH enzyme were investigated and also IC50 values and inhibition types. The metal ion with the lowest IC50 value is Ag+ (8.65 ± 1.68μM), and the vitamin is B6 (0.77 ± 0.04mM). The binding affinities of inhibitors were investigated with molecular docking, based on the conformational state of GDH.

SYNERGISTIC ANTI-TUMOUR EFFECT OF DOXORUBICIN-HYDROCHLORIDE WITH CRM197, AN INHIBITOR OF HB-EGF, IN SQUAMOUS-CELL CARCINOMA

Recent studies have shown that cross reacting material (CRM197), a nontoxic variant of diphtheria toxin, may play an important role in treating cancers with poor prognoses. Doxorubicin-hydrochloride (DOX) is an antineoplastic prescription medicine for the treatment of certain types of cancer. Considering that CRM197 is a known carrier in targeted delivery, CRM197-DOX complexes might be a step towards targeted therapy and reduced overall toxicity. Aim. This study aims to explore the potential to inhibit the growth of tumour cells. To achieve that goal, we evaluated the usage of CRM197-DOX complexes in squamous carcinoma cell line A431 and compared it with the effect on other immortalised cell lines. The methods used in this research include derivation and purification of recombinant CRM197 through immobilized-metal affinity chromatography and electrophoresis in a denaturing polyacrylamide gel. DOX-loaded CRM197 complexes were formed by the addition of a 5 μM solution of doxorubicin to 0.5 μg of protein with further dialysis in PBS. The cell viability assay was conducted using free CRM197 at different concentrations, DOX, CRM197 with DOX, as well as DOX-loaded CRM197. DOX-loaded CRM197 along with CRM197 with the addition of DOX showed significant differences in cell viability compared to control wells. CRM197- Results. DOX complexes have an evident inhibitory effect on epidermoid carcinoma cell growth and can be used as treatment against epithelial tumours, with CRM197 as a promising carrier for targeted drug delivery. Conclusions. CRM197-DOX complexes show evident inhibition of epidermoid carcinoma cell growth and can be used as treatment against epithelial tumours, especially those overexpressing the proHB-EGF and its receptors, EGFR1 and EGFR4, with CRM197 as a promising carrier for targeted drug delivery.

ASSESSMENT OF HIGH MOLECULAR WEIGHT PROTEINS IN SELECTED INDIGENOUS BREAD WHEAT VARIETIES OF PAKISTAN

Higher molecular weight gluten subunits (HMW-GS) articulate variation in allelic frequency, reflecting a strong correlation with bread quality. In order to determine this quality trait, 23 different Pakistani indigenous wheat varieties were screened that may be used as selection criteria in a breeding program. For detecting variations in HMW-GS, sodium dodecyl sulfate acrylamide gel electrophoresis was used. In all, 77 Glu-1 were identified including 25 at Glu-A1, 26 at Glu-B1 and 26 at Glu-D1. Alleles at Glu-1 were 2* with a frequency of 53.3% and N with 60% frequency at Glu-A1, 6+8 with 60%, 17+18 with 45 % at Glu-B1 and 5+10 with 60% and 72% at Glu-D1. The highest frequency of subunits 20 and 5+10 were found at Glu-B1-e and Glu-D1 (a), followed by a frequency of 2* and Null at Glu-A1 (b, c), which is then followed by 2+12 at GluD-1 (a). The lowest frequency of 13+16, 17+18 and 6+8 were observed at Glu-B1 (f, i, d), respectively. Glu-A1, Glu-B1, and Glu-D1 alleles showed genetic index (i.e. 0.587, 0.54), (0.587. 0.065 and 0.48, 0.39, respectively) with an average of 0.55 and 0.37. The glu-D1 locus has a lower genetic index comparatively. The composition N, 20, 5+10 was found in maximum number (4) in Fakhr-e-Sarhad, Pasban, Pirsabak-2004 and Tatara genotypes, followed by the composition of 2*, 20, 2+12 in one check (Marvi-2000) and two varieties i.e. Chakwal-97 and Bakhtawar-92. The results describing the allelic frequency and composition of bread wheat would benefit further breeding plans for wheat to select good quality parameters.

Development of the 12-Base Short Dimeric Myogenetic Oligodeoxynucleotide That Induces Myogenic Differentiation.

A myogenetic oligodeoxynucleotide (myoDN), iSN04 (5'-AGA TTA GGG TGA GGG TGA-3'), is a single-stranded 18-base telomeric DNA that serves as an anti-nucleolin aptamer and induces myogenic differentiation, which is expected to be a nucleic acid drug for the prevention of disease-associated muscle wasting. To improve the drug efficacy and synthesis cost of myoDN, shortening the sequence while maintaining its structure-based function is a major challenge. Here, we report the novel 12-base non-telomeric myoDN, iMyo01 (5'-TTG GGT GGG GAA-3'), which has comparable myogenic activity to iSN04. iMyo01 as well as iSN04 promoted myotube formation of primary-cultured human myoblasts with upregulation of myogenic gene expression. Both iMyo01 and iSN04 interacted with nucleolin, but iMyo01 did not bind to berberine, the isoquinoline alkaloid that stabilizes iSN04. Nuclear magnetic resonance revealed that iMyo01 forms a G-quadruplex structure despite its short sequence. Native polyacrylamide gel electrophoresis and a computational molecular dynamics simulation indicated that iMyo01 forms a homodimer to generate a G-quadruplex. These results provide new insights into the aptamer truncation technology that preserves aptamer conformation and bioactivity for the development of efficient nucleic acid drugs.

Single-cell SERS imaging of dual cell membrane receptors expression influenced by extracellular matrix stiffness

Membrane receptors perform a diverse range of cellular functions, accounting for more than half of all drug targets. The mechanical microenvironment regulates cell behaviors and phenotype. However, conventional analysis methods of membrane receptors often ignore the effects of the extracellular matrix stiffness, failing to reveal the heterogeneity of cell membrane receptors expression. Herein, we developed an in-situ surface-enhanced Raman scattering (SERS) imaging method to visualize single-cell membrane receptors on substrates with different stiffness. Two SERS substrates, Au@4-mercaptobenzonitrile@Ag@Sgc8c and Au@4-pethynylaniline@Ag@SYL3c, were employed to specifically target protein tyrosine kinase-7 (PTK7) and epithelial cell adhesion molecule (EpCAM), respectively. The polyacrylamide (PA) gels with tunable stiffness (2.5–25 kPa) were constructed to mimic extracellular matrix. The simultaneous SERS imaging of dual membrane receptors on single cancer cells on substrates with different stiffness was achieved. Our findings reveal decreased expression of PTK7 and EpCAM on cells cultured on stiffer substrates and higher migration ability of the cells. The results elucidate the heterogeneity of membrane receptors expression of cells cultured on the substrates with different stiffness. This single-cell analysis method offers an in-situ platform for investigating the impacts of extracellular matrix stiffness on the expression of membrane receptors, providing insights into the role of cell membrane receptors in cancer metastasis.

Proteomics reveals the mechanism of protein degradation and its relationship to sensorial and texture characteristics in dry-cured squid during processing

Proteolysis in dry-cured squid contributes to the development of sensory and textural attributes. In this study, label-free quantitative proteomics was conducted to study the mechanism of proteolysis and its correlation with quality changes. The results showed that the protein profile of dry-cured squid changed markedly during processing, which was confirmed by the quantification of myofibrillar protein, amino nitrogen and total free acids, and sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) analysis. Thirty-two key differentially abundant proteins were found to be correlated with sensory and texture characteristics, including myofibrillar protein, tubulin beta chain, collagens, heat shock proteins and cytochrome c. The correlation analysis indicated that myosin regulatory light chain and tubulin beta chain played the most important role in the development of texture and sensory attributes in squid samples during the dry-curing process. The results offered novel insights into proteolysis in dry-cured squid and its relationship to quality changes.

'Gel-Stacks' gently confine or reversibly immobilize arrays of single DNA molecules for manipulation and study.

Large DNA molecules (>20kb) are difficult analytes prone to breakage during serial manipulations and cannot be 'rescued' as full-length amplicons. Accordingly, to present, modify and analyze arrays of large, single DNA molecules, we created an easily realizable approach offering gentle confinement conditions or immobilization via spermidine condensation for controlled delivery of reagents that support live imaging by epifluorescence microscopy termed 'Gel-Stacks.' Molecules are locally confined between two hydrogel surfaces without covalent tethering to support time-lapse imaging and multistep workflows that accommodate large DNA molecules. With a thin polyacrylamide gel layer covalently bound to a glass surface as the base and swappable, reagent-infused, agarose slabs on top, DNA molecules are stably presented for imaging during reagent delivery by passive diffusion.