Explore the activation mechanism of alcalase activity with pulsed electric field treatment: Effects on enzyme activity, spatial conformation, molecular dynamics simulation and molecular docking parameters

Sustainable extraction of proteins from lime peels using ultrasound, deep eutectic solvents, and pressurized liquids, as a source of bioactive peptides

The aim of this work was to develop, for the first time, sustainable strategies, based on the use of Ultrasound-Assisted Extraction, Natural Deep Eutectic Solvents, and Pressurized Liquid Extraction, to extract proteins from lime (Citrus x latifolia) peels and to evaluate their potential to release bioactive peptides. PLE showed the largest extraction of proteins (66-69%), which were hydrolysed using three different enzymes (Alcalase 2.4 L FG, Alcalase®PURE 2.4 L, and Thermolysin). The in vitro antioxidant and antihypertensive activities of released peptides were evaluated. Although all hydrolysates showed antioxidant and antihypertensive activity, the hydrolysate obtained with Thermolysin showed the most significant values. Since the Total Phenolic Content in all hydrolysates was low, peptides were likely the main contributors to these bioactivities. Hydrolysates were analyzed by UHPLC-QTOF-MS and a total of 98 different peptides were identified. Most of these peptides were rich in amino acids associated with antioxidant activity.

Unraveling the binding mechanisms of transglutaminase and substrate subjected to microwaves: Molecular docking and molecular dynamic simulations

Previous studies showed that transglutaminase (TGase) and microwaves acted synergistically to improve the functional properties of proteins. The mechanism behind this has yet to be elucidated. In this study, the phenomenon of microwaves enhancing TGase activity was experimentally validated. Molecular docking and molecular dynamics simulations revealed that moderate microwaves (105 and 108 V/m) increased the structural flexibility of TGase and promoted the orientation of the side chain carboxylate anion group on Asp255, driving the reaction forward. Also, TGase underwent partial transformation from α-helix to turns or coils at 105 and 108 V/m, exposing more residues in the active site and facilitating the binding of the substrate (CBZ-Gln-Gly) to TGase. However, 109 V/m microwaves completely destroyed the TGase structure, inactivating the enzyme. This study provides insights into the molecular mechanisms underlying the interactions between TGase and substrate subjected to microwaves, promoting the future applications of TGase and microwaves in food processing.

Non-animal protein hydrolysates from agro-industrial wastes: A prospect of alternative inputs for cultured meat

In light of the growing demand for alternative protein sources, laboratory-grown meat has been proposed as a potential solution to the challenges posed by conventional meat production. Cultured meat does not require animal slaughter and uses sustainable production methods, contributing to animal welfare, human health, and environmental sustainability. However, some challenges still need to be addressed in cultured meat production, such as the use of fetal bovine serum for medium supplementation. This ingredient has limited availability, increases production costs, and raises ethical concerns. This review explores the potential of non-animal protein hydrolysates derived from agro-industrial wastes as substitutes for critical components of fetal bovine serum in cultured meat production. Despite the lack of standardization of hydrolysate composition, the potential benefits of this alternative protein source may outweigh its disadvantages. Future research holds promise for increasing the accessibility of cultured meat.

MD simulation to comprehend polygalacturonase inactivation mechanism during thermal and non-thermal effects of infrared processing

Food quality is greatly impacted by traditional heat methods for polygalacturonase (PG) inactivation; therefore, it's imperative to develop a novel infrared (IR) inactivation approach and identify its mechanism. Utilizing molecular dynamics (MD) simulation, this study verified the PG's activity, structure, active sites, and substrate channel under the single thermal and non-thermal effects of IR. PG activity was significantly reduced by IR, and structure was unfolded by increasing random coils (65.62 %) and decreasing β-sheets (29.11 %). MD data indicated that the relative locations of PG's active sites were altered by both IR effects, and the enzyme-substrate channel was shortened (10.53 % at 18 μm and 15.79 % at 80 °C). The thermal effect of IR on the inactivation of PG was significantly more pronounced than its non-thermal effect. This study unveiled the mechanism by which the infrared disrupted PG's activity, active sites, and substrate channels; thus, it expanded the infrared technique's efficacy in enzyme control.

Elucidating the mechanisms of ultrasound treatment combined with κ-carrageenan addition enhancing the gelling properties of heat-induced myofibrillar protein gel

This work investigated the effect of ultrasound (US) treatment synergized with κ-carrageenan (KC) on the gel properties, structural characteristics and microstructures of myofibrillar protein (MP) gel. The results demonstrated that simply adding KC enhanced the gel strength and water holding capacity (WHC) of MP gels. Moreover, the gel strength and WHC of MP gels were increased by 56.67 % and 76.19 % via 20 min US treatment synergized with KC, which was mainly attributed to the changes in sulfhydryl content, surface hydrophobicity, and fluorescence intensity of MP gels. Based on the results of molecular docking and secondary structure, it can be hypothesized that the synergistic effect resulted in the rearrangement of the proteins, which altered the interaction site between MP gels and KC, accompanied by stronger binding. Furthermore, the microstructural results indicated that moderate US treatment (20 min) facilitated the production of a more compact and denser MP gels matrix with uniformly sized and distributed pores. However, excessive US treatment (40 and 50 min) caused the MP gels to form looser and disordered gel structure, which reduced the gel strength and WHC. This study suggested that combining of US and KC was a potential tactic to enhance the gelling properties of heat-induced MP gels.

Exploring novel Kokumi peptides in Agaricus bisporus: selection, identification, and tasting mechanism investigation through sensory evaluation and computer simulation analysis

Agaricus bisporus contains amino acids associated with thickness and full-mouthfeel, making it a potential candidate for salt substitutes and flavor enhancers in various food applications. Kokumi peptides were isolated from the enzymatic digest of Agaricus bisporus using ultrafiltration nanofiltration, gel chromatographic separation, and RP-HPLC, coupled with sensory evaluation. Subsequently, the peptides, EWVPVTK and EYPPLGR, were selected for solid-phase synthesis based on molecular docking. Sensory analysis, including thresholds, time intensity, and dose-configuration relationships, indicated that EWVPVTK and EYPPLGR exhibited odor thresholds of 0.6021 mmol L-1 and 2.332 mmol L-1 in an aqueous solution. Molecular docking scores correlated with low sensory thresholds, signifying strong taste sensitivities. EWVPVTK, in particular, demonstrated a higher sense of richness at lower concentrations compared to EYPPLGR. Molecular docking and dynamics simulations elucidated that the interactions between Kokumi peptides and the CaSR receptor primarily involved hydrogen bonding, electrostatic interactions, and hydrophobic interactions. Both EWVPVTK and EYPPLGR exhibited stable binding to the CaSR receptor. Active binding sites were identified, with EWVPVTK interacting at Arg 66, Asp 216, Gln 245, and Asn 102, while EYPPLGR engaged with Ser 272, Gln 193, Glu 297, Ala-298, Tyr-2, and Agr-66 in hydrophilic interactions through hydrogen bonds. Notably, these two Kokumi peptides were found to be enriched in umami and sweet amino acids, underscoring their pivotal role in umami perception. This study not only identifies novel Kokumi peptides from Agaricus bisporus but also contributes theoretical foundations and insights for future studies in the realm of Kokumi peptides.

Regulation of ovalbumin allergenicity and structure-activity relationship analysis based on pulsed electric field technology

The study focused on the regulation of ovalbumin (OVA) allergenicity using pulsed electric field (PEF) technology and examined the structure-activity link. Following PEF treatment, the ability of OVA to bind to IgE and IgG1 at 6 kHz was inhibited by 30.41 %. According to the microstructure, PEF caused cracks on the OVA surface. Spectral analysis revealed a blue shift in the amide I band and a decrease in α-helix and β-sheet content indicating that the structure of OVA was unfolded. The disulfide bond conformation was transformed and the structure tended to be disordered. The increased fluorescence intensity indicated that tryptophan and tyrosine were exposed which led an increase in hydrophobicity. In addition, the results of molecular dynamics (MD) simulations confirmed that the stability of OVA was reduced after PEF, which was related to the reduction of hydrogen bonding and the sharp fluctuation of aspartic acid. Therefore, PEF treatment induced the exposure of hydrophobic amino acids and the transformation of disulfide bond configuration which in turn masked or destroyed allergenic epitopes, and ultimately inhibited OVA allergenicity. This study provided insightful information for the production of hypoallergenic eggs and promoted the use of PEF techniques in the food field.

Assessment of cell wall degrading enzymes by molecular docking and dynamics simulations: Effects of novel infrared treatment

Cell wall-degrading enzymes' activities under infrared treatment are vital for peeling; it is critical to elucidate the mechanisms of the novel infrared peeling in relation to its impact on cell wall-degrading enzymes. In this study, the activities, and gene expressions of eight degrading enzymes closely related to pectin, cellulose and hemicellulose were determined. The most influential enzyme was selected from them, and then the mechanism of its changes was revealed by molecular dynamics simulation and molecular docking. The results demonstrated that infrared had the most significant effect on β-glucosidase among the tested enzymes (increased activity and up-regulated gene expression of 195.65 % and 7.08, respectively). It is suggested infrared crucially promotes cell wall degradation by affecting β-glucosidase. After infrared treatment, β-glucosidase's structure moderately transformed to a more open one and became flexible, increasing the affinity between β-glucosidase and substrate (increasing 75 % H-bonds and shortening 15.89 % average length), thereby improving β-glucosidase's activity. It contributed to cell wall degradation. The conclusion is that the effect of infrared on the activity, gene expression and molecular structure of β-glucosidase causes damage to the peel, thus broadening the applicability of the new infrared dry-peeling technique, which has the potential to replace traditional wet-peeling methods.

Cryoprotective effect of soybean oil on surimi gels and the mechanism based on molecular dynamics simulation

The effect of soybean oil (SO) on freeze-thaw (F-T)-treated surimi was investigated and its related mechanism was revealed by molecular dynamics (MD) simulations. The results displayed that SO has a disrupting effect on the structure of fresh samples. However, in the F-T-treated samples, surimi gels supplemented with SO had a more uniform microstructure. Simultaneously, when SO was added from 0% to 7% in the F-T-treated samples, the gel strength increased from46.66 to 51.86 N · mm $$ 46.66\ \mathrm{to}\ 51.86\;\mathrm{N}\cdotp \mathrm{mm} $$ (p < .05), the physically bound water was increased from 92.90% to 94.15% (p < .05), and storage modulus was increased from 5939 to 6523 Pa. Triglycerides of SO generated hydrophobic interactions with myosin mainly in carbon chains. Computational results from MD simulations illustrated that the structure of myosin combined with triglycerides was more stable than that of myosin alone during temperature fluctuations (-20 to 4°C). During ice crystal growth, triglycerides absorbed on the myosin surface inhibited the growth of surrounding ice crystals and mitigated the ice crystal growth rate (from 7.54 to 5.99 cm/s). The addition of SO during the F-T treatments allowed myosin to be less negatively affected by ice crystal formation and temperature fluctuations and ultimately contributed to the formation of a more uniform network gel structure.

Modification of low-salt myofibrillar protein using combined ultrasound pre-treatment and konjac glucomannan for improving gelling properties: Intermolecular interaction and filling effect

The quality deterioration of low-salt meat products has been gained ongoing focus of researchers. In this study, konjac glucomannan (KGM) was used to alleviate the finiteness of ultrasound treatment on the quality improvement of low-salt myofibrillar protein (MP), and the modification sequence was also investigated. The results revealed that the single and double sequential modification by utilizing KGM and ultrasound significantly influenced the gelation behavior of low-salt MPs. The uniform MP-KGM mixture formed by a single ultrasound treatment had limited protein unfolding, resulting in relatively weak intermolecular forces in the composite gel. Importantly, ultrasound pre-treatment combined with KGM modification promoted the unfolding and moderate thermal aggregation of proteins and remarkably improved the rheological behaviors and gel strength of the composite gel. This result could also be corroborated by the highest percentage of trans-gauche-trans conformation of SS bridges and maximum β-sheet proportion. Furthermore, molecular dynamic simulation and molecular docking elucidated that the hydrogen bond length between protein and KGM was shortened after ultrasound pre-treatment, which was the molecular basis for the enhanced intermolecular interactions. Therefore, ultrasound pre-treatment combined with KGM can effectively improve the gelling properties of low-salt MPs, providing a practical method for the processing of low-salt meat products.

Pulsed Electric Field-Assisted Alcalase Treatment Reduces the Allergenicity and Eliminates the Antigenic Epitopes of Ovomucoid

Physically assisted chemical modifications can effectively reduce the allergenicity of ovomucoid (OVM). However, only a few studies have used pulsed electric field (PEF)-assisted alcalase hydrolysis to reduce the allergenicity of OVM. Herein, we investigated the effect of PEF-assisted alcalase treatment on the spatial conformation, allergenicity, and antigenic epitopes of OVM based on multispectroscopic analyses, bioinformatics, and mass spectrometry. The results showed that PEF-assisted alcalase treatment promoted the hydrolysis of OVM; moreover, the α-helix content and surface hydrophobicity of OVM significantly decreased, which disordered its spatial conformation and weakened its intermolecular interactions. Additionally, enzyme-linked immunosorbent assay (ELISA) results showed that the PEF-assisted alcalase treatment significantly reduced the binding levels of IgE and IgG1, which were 47.66 and 36.41%, respectively. Finally, eight epitopes of OVM were obtained by immunoinformatic tools. Nano-high performance liquid chromatography coupled to tandem mass spectrometry (nano-HPLC MS/MS) results showed that the hydrolysate of OVM and alcalase (HOVM) had nine more peptide-containing epitopes than the hydrolysate of PEF-treated OVM and PEF-treated alcalase (HOVM-PP'), indicating that PEF could promote the elimination of linear epitopes in OVM, thereby reducing OVM allergenicity.

Design of highly active substrates using molecular docking for microbial transglutaminase detection

The transglutaminase (TGase) family catalyzes a transamidation reaction between glutamine (Gln) and lysine (Lys) residues on protein substrates. Highly active substrates are important for cross-linking and modifying proteins of TGase. In the present work, high-activity substrates have been designed based on the principles of enzyme-substrate interaction, using microbial transglutaminase (mTGase) as a research model of the TGase family. Substrates with high activity were screened using a combination of molecular docking and traditional experiments. Twenty-four sets of peptide substrates all produced good catalytic activity with mTGase. FFKKAYAV as the acyl acceptor and VLQRAY as the acyl donor group had the best reaction efficiency with highly sensitive detection of 26 nM mTGase. In addition, the substrate grouping, KAYAV and AFQSAY, detected 130 nM mTGase under physiological conditions (37 °C, pH 7.4), producing 20-fold higher activity than the natural substrate, collagen. The experimental results confirmed the potential for design of high-activity substrates by a combination of molecular docking and traditional experiments under physiological conditions.

Cardiac Contractility Modulation Therapy in Patients with Amyloid Cardiomyopathy and Heart Failure, Case Report, Review of the Biophysics of CCM Function, and AMY-CCM Registry Presentation

Cardiac amyloidosis may result in an aggressive form of heart failure (HF). Cardiac contractility modulation (CCM) has been shown to be a concrete therapeutic option in patients with symptomatic HF, but there is no evidence of its application in patients with cardiac amyloidosis. We present the case of TTR amyloidosis, where CCM therapy proved to be effective. The patient had a history of multiple HF hospitalizations due to an established diagnosis of wild type TTR-Amyloidosis with significant cardiac involvement. Since he was highly symptomatic, except during continuous dobutamine and diuretic infusion, it was opted to pursue CCM therapy device implantation. At follow up, a significant improvement in clinical status was reported with an increase of EF, functional status (6 min walk test improved from zero meters at baseline, to 270 m at 1 month and to 460 m at 12 months), and a reduction in pulmonary pressures. One year after device implantation, no other HF hospital admission was needed. CCM therapy may be effective in this difficult clinical setting. The AMY-CCM Registry, which has just begun, will evaluate the efficacy of CCM in patients with HF and diagnosed TTR amyloidosis to bring new evidence on its potential impact as a therapeutic option.