Plant proteases for bioactive peptides release: A review

Enhancing the Functional and Emulsifying Properties of Potato Protein via Enzymatic Hydrolysis with Papain and Bromelain for Gluten-Free Cake Emulsifiers

In recent years, plant-derived food proteins have gained increasing attention due to their economic, ecological, and health benefits. This study aimed to enhance the functional properties of potato protein isolate (PPI) through enzymatic hydrolysis with papain and bromelain, evaluating the physicochemical and emulsifying characteristics of the resulting potato protein hydrolysates (PPHs) for their potential use as plant-based emulsifiers. PPHs were prepared at various hydrolysis times (0.25-2 h), resulting in reduced molecular weights and improved solubility under acidic conditions (pH 4-6). PPHs exhibited higher ABTS radical-scavenging activity than PPI. The foaming stability (FS) of bromelain-treated PPI was maintained, whereas papain-treated PPI showed decreased FS with increased hydrolysis. Bromelain-treated PPHs demonstrated a superior emulsifying activity index (EAI: 306 m2/g), polydispersity index (PDI), higher surface potential, and higher viscosity compared to papain-treated PPHs, particularly after 15 min of hydrolysis. Incorporating PPHs into gluten-free chiffon rice cake batter reduced the batter density, increased the specific volume, and improved the cake's textural properties, including springiness, cohesiveness, and resilience. These findings suggest that bromelain-treated PPHs are promising plant-based emulsifiers with applications in food systems requiring enhanced stability and functionality.

Highly Efficient Chiral Separation Based on Alkali-proof Protein Immobilization by Covalent Organic Frameworks

Chiral separation plays a pivotal role in both practical applications and industrial productions. However, traditional chiral stationary phases (CSPs) exhibit inherent instability in alkaline environments, presenting a significant challenge despite their importance. Herein, basophilic alcalase is creatively developed to fabricate ultrastable protein-based CSPs that can efficiently work under alkaline conditions. An in-depth theoretical simulation is conducted to unveil the unique three-dimensional conformation of alcalase, showing selective affinity towards various enantiomers of chiral amino acids and drugs, especially acidic substrates. Subsequently, an in situ assembly strategy is used to immobilize alcalase within a hydrazone-linked covalent organic framework (COF) platform. The generated protein-based CSPs enable successful baseline separation (Rs≥1.50) for various value-added compounds (e.g., non-steroidal drug, RS-flurbiprofen; nucleotide analog, RS-tenofovir) via high-performance liquid chromatography, surpassing the commercial chiral column. Furthermore, a systematic study reveals that increasing hydrophilicity and pore sizes of COFs can enhance the separation performance. Remarkably, the obtained CSPs demonstrated exceptional durability, maintaining performance for >2,400 runs. This study provides a new member to the protein library for CSPs, and represents an innovative and effective platform for CSPs with immense potential for the enantioseparation of acidic drugs.

Antinutritional factors and protein digestibility of broad bean flours hydrolysed during soaking using vacuum enzyme impregnation

The hydrolysis of legume proteins improves their nutritional and functional properties. Usually done by mixing flour with an enzyme solution, the process can be simplified using vacuum enzyme impregnation during soaking. This study used vacuum impregnation with papain or bromelain to obtain hydrolysed broad bean flours. It examined the impact of vacuum impregnation and enzyme incorporation on hydration kinetics and the impact of hydrolysis and dehulling on antinutritional factors and protein digestibility. Vacuum impregnation accelerated hydration and enzyme incorporation did not alter the hydration rate. Maximum hydrolysis degrees were 9.1 % with papain and 8.8 % with bromelain after 4 h of soaking. Hydrolysis increased phytic acid, total phenolics, and tannins content while decreasing trypsin inhibitors. Dehulling increased phytic acid and trypsin inhibitors, reduced tannins, and enhanced protein digestibility. Vacuum enzyme impregnation during soaking was effective for hydration and protein hydrolysis, modifying the nutritional properties of broad bean flours.

Exploring the Pharmacological Effects of Bioactive Peptides on Human Nervous Disorders: A Comprehensive Review

A family of peptides known as bioactive peptides has unique physiological properties and may be used to improve human health and prevent illness. Because bioactive peptides impact the immunological, endocrine, neurological, and cardiovascular systems, they have drawn a lot of interest from researchers. According to recent studies, bioactive peptides have a lot to offer in the treatment of inflammation, neuronal regeneration, localized ischemia, and the blood-brain barrier. It investigates various peptide moieties, including antioxidative properties, immune response modulation, and increased blood-brain barrier permeability. It also looks at how well they work as therapeutic candidates and finds promising peptide-based strategies for better outcomes. Furthermore, it underscores the need for further studies to support their clinical utility and suggests that results from such investigations will enhance our understanding of the pathophysiology of these conditions. In order to understand recent advances in BPs and to plan future research, academic researchers and industrial partners will find this review article to be a helpful resource.

Purification and characterization of limonin D-ring lactone hydrolase from sweet orange (Citrus sinensis (L.) Osbeck) seeds

BACKGROUND

Citrus products often suffer from delayed bitterness, which is generated from the conversion of non-bitter precursors (limonoate A-ring lactone, LARL) to limonin under the catalysis of limonin D-ring lactone hydrolase (LDLH). In this study, LDLH was isolated and purified from sweet orange seeds, and a rapid and accurate high-performance liquid chromatography method to quantify LARL was developed and applied to analyze the activity and enzymatic properties of purified LDLH.

RESULTS

Purified LDLH (25.22 U mg-1) showed bands of 245 kDa and 17.5 kDa molecular weights in native polyacrylamide gel electrophoresis (PAGE) and sodium dodecyl sulfate PAGE analysis respectively. After a 24 h incubation under strongly acidic (pH 3) or strongly alkaline (pH 9) conditions, LDLH still retained approximately 100% activity. Moreover, LDLH activity was not impaired by thermal treatment at 50 °C for 120 min. Enzyme inhibition assays showed that LDLH was inactivated only after ethylenediaminetetraacetic acid treatment, and other enzyme inhibitors showed no significant effect on its activity. In addition, the LDLH activity of calcium ion (Ca2+) intervention was 108% of that in the blank group, and that of zinc ion (Zn2+) intervention was 71%.

CONCLUSION

LDLH purified in this study was a multimer containing 17.5 kDa monomer with a wide pH tolerance range (pH 3-9) and excellent thermal stability. Moreover, LDLH might be a metallopeptidase, and its activity was stimulated by Ca2+ and significantly inhibited by Zn2+. These findings improve our understanding of LDLH and provide some important implications for reducing the bitterness in citrus products in the future. © 2024 Society of Chemical Industry.

Peptides Used for Heavy Metal Remediation: A Promising Approach

In recent years, heavy metal pollution has become increasingly prominent, severely damaging ecosystems and biodiversity, and posing a serious threat to human health. However, the results of current methods for heavy metal restoration are not satisfactory, so it is urgent to find a new and effective method. Peptides are the units that make up proteins, with small molecular weights and strong biological activities. They can effectively repair proteins by forming complexes, reducing heavy metal ions, activating the plant's antioxidant defense system, and promoting the growth and metabolism of microorganisms. Peptides show great potential for the remediation of heavy metal contamination due to their special structure and properties. This paper reviews the research progress in recent years on the use of peptides to remediate heavy metal pollution, describes the mechanisms and applications of remediation, and provides references for the remediation of heavy metal pollution.

Characterization and Hydrolysis Mechanism Analysis of a Cold-Adapted Trypsin-Like Protease from Antarctic Krill

Cold-adapted proteases are capable of efficient protein hydrolysis at reduced temperatures, which offer significant potential applications in the area of low temperature food processing. In this paper, we attempted to characterize cold-adapted proteases from Antarctic krill. Antarctic krill possesses an extremely active autolytic enzyme system in their bodies, and the production of peptides and free amino acids accompanies the rapid breakdown of muscle proteins following the death. The crucial role of trypsin in this process is recognized. A cold-adapted trypsin named OUC-Pp-20 from Antarctic krill genome was cloned and expressed in Pichia pastoris. Recombinant trypsin is a monomeric protein of 26.8 ± 1.0 kDa with optimum reaction temperature at 25 °C. In addition, the catalytic specificity of OUC-Pp-20 was assessed by identifying its hydrolysis sites through LC-MS/MS. OUC-Pp-20 appeared to prefer Gln and Asn at the P1 position, which is an amino acid with an amide group in its side chain. Hydrolysis reactions on milk and shrimp meat revealed that it can effectively degrade allergenic components in milk and arginine kinase in shrimp meat. These findings update the current knowledge of cold-adapted trypsin and demonstrate the potential application of OUC-Pp-20 in low temperature food processing.

Starter molds and multi-enzyme catalysis in koji fermentation of soy sauce brewing: A review

Soy sauce is a traditional fermented food produced from soybean and wheat under the action of microorganisms. The soy sauce brewing process mainly involves two steps, namely koji fermentation and moromi fermentation. In the koji fermentation process, enzymes from starter molds, such as protease, aminopeptidase, carboxypeptidase, l-glutaminase, amylase, and cellulase, hydrolyze the protein and starch in the raw ingredients to produce short-chain substances. However, the enzymatic reactions may be diminished after being subjected to moromi fermentation due to its high NaCl concentration. These enzymatically hydrolyzed products are further metabolized by lactic acid bacteria and yeasts during the moromi fermentation process into organic acids and aromatic compounds, giving soy sauce a unique flavor. Thus, the starter molds, such as Aspergillus oryzae, Aspergillus sojae, and Aspergillus niger, and their secreted enzymes play crucial roles in soy sauce brewing. This review comprehensively covers the characteristics of the starter molds mainly used in soy sauce brewing, the enzymes produced by starter molds, and the roles of enzymes in the degradation of raw material. We also enumerate current problems in the production of soy sauce, aiming to offer some directions for the improvement of soy sauce taste.

Osteoarthritis: Insights into Diagnosis, Pathophysiology, Therapeutic Avenues, and the Potential of Natural Extracts

Osteoarthritis (OA) stands as a prevalent and progressively debilitating clinical condition globally, impacting joint structures and leading to their gradual deterioration through inflammatory mechanisms. While both non-modifiable and modifiable factors contribute to its onset, numerous aspects of OA pathophysiology remain elusive despite considerable research strides. Presently, diagnosis heavily relies on clinician expertise and meticulous differential diagnosis to exclude other joint-affecting conditions. Therapeutic approaches for OA predominantly focus on patient education for self-management alongside tailored exercise regimens, often complemented by various pharmacological interventions primarily targeting pain alleviation. However, pharmacological treatments typically exhibit short-term efficacy and local and/or systemic side effects, with prosthetic surgery being the ultimate resolution in severe cases. Thus, exploring the potential integration or substitution of conventional drug therapies with natural compounds and extracts emerges as a promising frontier in enhancing OA management. These alternatives offer improved safety profiles and possess the potential to target specific dysregulated pathways implicated in OA pathogenesis, thereby presenting a holistic approach to address the condition's complexities.

Renewing the potential of rice crop residues as value-added products in the cosmetics industry

Purpose of this study is to explore the extraction of potentially valuable cosmetic ingredients from rice crop residues, aiming to mitigate their environmental impact.

Methods

We employed AOAC methods to analyze the fat, protein, ash, fiber, soluble, and insoluble carbohydrate content in these residues. To identify sugars rich in galactose and acidic sugars, a total soluble carbohydrate extraction was performed. Cellulose, as part of the insoluble carbohydrates, was isolated through alkaline and acid hydrolysis, while sodium silicate was derived from the ash. Characterization of insoluble cellulose and silicate involved techniques like FTIR, DSC, PXRD, microphotography, porosity assessments, and water absorption studies. For proteins, alkaline solubilization and precipitation at the isoelectric point were utilized, with quantification via BCA and amino acid profiling through gas chromatography. Evaluation of radical scavenging capacity using DPPH led to the calculation of apparent molecular weight via SDS-PAGE.

Results

The results revealed low levels of gum, mucilage, and pectin in both residues, contrasting with a high concentration of insoluble polysaccharides. Among these, Iβ cellulose displayed potential attributes for cosmetic applications due to its oil and water adsorption characteristics. However, silicates obtained from the ashes did not exhibit direct use potential. In terms of protein extraction, we observed antioxidant properties, with enhanced performance through enzymatic hydrolysis, achieving a hydrolysis degree of 30.41% and a DPPH radical absorption rate exceeding 70%.

Conclusion

Rice residues, particularly husk and straw, shown valuable substances suitable for potential cosmetic applications, encompassing cellulose, hydrolyzed proteins, and ash as a silicate precursor.

Bromelain can reduce the negative effects of a subclinical necrotic enteritis in broiler chickens

This study was conducted to examine the efficacy of a bromelain-based supplementation coded ANR-pf on growth performance and intestinal lesion of broiler chickens under necrotic enteritis (NE) challenge. A total of 540 Ross 308 day-old male chicks were randomly allocated into 6 treatments of 6 replicates. The bromelain formulation was delivered to chickens through gavaging or in drinking water method twice, on d 8 and 13. Nonchallenged groups included 1) without or 2) with the specific bromelain formulation gavaged at 0.8 mL/kg. NE-challenged groups included 3) without the specific bromelain formulation; 4) gavaged with 0.4 mL/kg; 5) gavaged with 0.8 mL/kg and 6) supplemented with 0.8 mL/kg via drinking water. Birds were challenged with Eimeria spp. on d 9 and Clostridium perfringens (NE-18 strain) on d 14 and 15. On d 14 and 19, fresh faecal contents were collected for the determination of oocyst counts. Intestinal lesion scores were determined on d16. Performance and mortality were recorded throughout the entire experiment. Among challenged groups, birds received additive via drinking water had higher weight gain (WG) compared to the remaining groups (P < 0.001) in the grower phase and had lower FCR compared to 0.4 mL/kg inoculated group in the grower and finisher phases (P < 0.001). Bromelain supplementation via drinking water improved the WG of challenged birds, similar to that of the nonchallenged birds (P < 0.001), and lowered FCR compared to other challenged groups (P < 0.001). Nonchallenged birds and birds that received bromelain formulation in drinking water did not have lesions throughout the small intestine whereas challenged birds, either un-supplemented or supplemented with bromelain via inoculation route recorded similar lesion score levels in the jejunum. At d 19, birds received bromelain in drinking water had lower fecal oocyst numbers compared to challenged birds without additive (P < 0.001). In conclusion, bromelain administration via drinking water could ameliorate the negative impacts of NE-infection in broilers by improving performance, lowering the oocyst numbers and lesion scores.

Hempseed protein-derived short- and medium-chain peptides and their multifunctional properties

Nowadays, the growing knowledge about the high nutritional value and potential functionality of hempseeds, the edible fruits of the Cannabis sativa L. plant, has sparked a surge in interest in exploring the worthwhile attributes of hempseed proteins and peptides. This trend aligns with the increasing popularity of hemp-based food, assuming a vital role in the global food chain. This chapter targets the nutritional and chemical composition of hempseed in terms of short- and medium-chain bioactive peptides. The analytical approaches for their characterization and multifunctional properties are summarized in detail. Moreover, the processing, functionality, and application of various hempseed protein products are discussed. In the final part of the chapter-for evaluating their propensity to be transported by intestinal cells-the transepithelial transport of peptides within hempseed protein hydrolysate is highlighted.

Partial purification and characterization of protease extracted from kinema

Proteases are large group of highly demanded enzymes having huge application in food and pharmaceutical industries. Numerous sources, including plants, microorganisms, and animals, can be used to obtain protease. Due to its affordability and safety consideration, fermented foods have recently attracted more attention as a source of microbial protease. The present study aimed to extract protease from kinema, partially purify the extracted protease following dialysis after precipitation with ammonium sulfate, and determine general characteristics of protease. The kinema having highest proteolysis activity after three days of control fermentation (Temperature 30±2 °C, RH 66 ± 2%) was taken for the study. About 2.45 fold of purification with overall recovery of 63.21% was achieved after precipitation with ammonium sulfate at 30-70% saturation level followed by dialysis of crude extracted protease. The dialysed kinema protease had specific activity of 7.90 U/mg. The enzyme remained actively functional across a wider pH (5-9) and temperature (40-60 °C) range. SDS-PAGE and Zymogram confirmed the presence of three major active bands respectively of 29.04 kDa, 36.09 kDa and 46.35 kDa in the kinema protease extract. The enzyme kinetics data on casein, fitted to Mechaelis Mentens' plots showed the protease had Vmax of 1.001 U/ml with corresponding Km value of 0.825 mg/ml. Metal ions such as iron, mercury and aluminium showed the inhibition effect whereas presence of sodium, zinc, and calcium shows the activation effect on protease performance. The enzyme was active over various natural substrates; showing maximal activity on casein, and subsequent to bovine serum albumin, gelatin, hemoglobin and whey protein respectively. Furthermore, molecular weight distribution of the protease extract and activity inhibition with ethylenediaminetetraacetic acid and phenylmethylsulfonyl fluoride, suggesting the protease from kinema could be a metal dependent serine protease or mixture of them.

Peptides with biological and technofunctional properties produced by bromelain hydrolysis of proteins from different sources: A review

Bromelains are cysteine peptidases with endopeptidase action (a subfamily of papains), obtained from different parts of vegetable belonging to the Bromeliaceae family. They have some intrinsic medical activity, but this review is focused on their application (individually or mixed with other proteases) to produce bioactive peptides. When compared to other proteases, perhaps due to the fact that they are commercialized as an extract containing several proteases, the hydrolysates produced by this enzyme tends to have higher bioactivities than other common proteases. The peptides and the intensity of their final properties depend on the substrate protein and reaction conditions, being the degree of hydrolysis a determining parameter (but not always positive or negative). The produced peptides may have diverse activities such as antioxidant, antitumoral, antihypertensive or antimicrobial ones, among others or they may be utilized to improve the organoleptic properties of foods and feeds. Evolution of the use of this enzyme in this application is proposed to be based on a more intense direct application of Bromeliaceae extract, without the cost associated to enzyme purification, and the use of immobilized biocatalysts of the enzyme by simplifying the enzyme recovery and reuse, and also making the sequential hydrolysis using diverse proteases possible.

Functionalized activated carbon as support for trypsin immobilization and its application in casein hydrolysis

This study aimed to immobilize trypsin on activated carbon submitted to different surface modifications and its application in casein hydrolysis. With the aim of determining which support can promote better maintenance of the immobilized enzyme. Results showed that pH 5.0 was obtained as optimal for immobilization and pH 9.0 for the casein hydrolysis reaction for activated carbon and glutaraldehyde functionalized carbon. Among the supports used, activated carbon modified with iron ions in the presence of a chelating agent was the one that showed best results, under the conditions evaluated in this study. Presenting an immobilization yield of 95.15% and a hydrolytic activity of 4.11 U, same as soluble enzyme (3.76 U). This derivative kept its activity stable at temperatures above 40 °C for1 h and when stored for 30 days at 5 °C. Furthermore, it was effective for more than 6 reuse cycles (under the same conditions as the 1st cycle). In general, immobilization of trypsin on metallized activated carbon can be an alternative to biocatalysis, highlighting the advantages of protease immobilization.

Role of Enzymatic Reactions in Meat Processing and Use of Emerging Technologies for Process Intensification

Meat processing involves different transformations in the animal muscle after slaughtering, which results in changes in tenderness, aroma and colour, determining the quality of the final meat product. Enzymatic glycolysis, proteolysis and lipolysis play a key role in the conversion of muscle into meat. The accurate control of enzymatic reactions in meat muscle is complicated due to the numerous influential factors, as well as its low reaction rate. Moreover, exogenous enzymes are also used in the meat industry to produce restructured products (transglutaminase), to obtain bioactive peptides (peptides with antioxidant, antihypertensive and gastrointestinal activity) and to promote meat tenderization (papain, bromelain, ficin, zingibain, cucumisin and actinidin). Emerging technologies, such as ultrasound (US), pulsed electric fields (PEF), moderate electric fields (MEF), high-pressure processing (HPP) or supercritical CO₂ (SC-CO₂), have been used to intensify enzymatic reactions in different food applications. This review aims to provide an overview of the enzymatic reactions taking place during the processing of meat products, how they could be intensified by using emerging technologies and envisage potential applications.

Protease-catalyzed synthesis of α-poly-L-Lysine and amphiphilic poly(L-lysine-co-L-phenylalanine) in a neat non-toxic organic solvent

Subtilisin Carlsberg (alkaline protease from Bacillus licheniformis) catalyzes the syntheses of high molecular weights (ca. 20 KDa) cationic α-poly-L-lysine and amphiphilic poly(α-L-lysine-co-L-phenylalanine) in neat organic solvent. The synthesis is conducted in liquid 1,1,1,2-tetrafluoroethane solvent, which is a hydrophobic non-toxic gas that does not deplete the ozone layer and approved for pharmaceutical applications. Solubility of substrates and adequate protease activity in this system with low water environment limits the reaction of hydrolysis of the growing peptide chains. The pressurization of this organic compressed fluid to liquid has low-pressure requirements (25 bar, 40 ºC), and its complete evaporation at atmospheric pressure after completing the reaction ensures solvent-free residues in products. The resulting polypeptides present null cytotoxicity according to MTT and NR analyses, as well as Calcein/EthD-1 assay in human cells.

In Silico Identification of Peptides with PPARγ Antagonism in Protein Hydrolysate from Rice (Oryza sativa)

At least half the population in industrialized countries suffers from obesity due to excessive accumulation of adipose tissue. Recently, rice (Oryza sativa) proteins have been considered valuable sources of bioactive peptides with antiadipogenic potential. In this study, the digestibility and bioaccessibility in vitro of a novel protein concentrate (NPC) from rice were determined through INFOGEST protocols. Furthermore, the presence of prolamin and glutelin was evaluated via SDS-PAGE, and their potential digestibility and the bioactivity of ligands against peroxisome proliferator-activated receptor gamma (PPARγ) were explored by BIOPEP UWM and HPEPDOCK. For the top candidates, molecular simulations were conducted using Autodock Vina to evaluate their binding affinity against the antiadipogenic region of PPARγ and their pharmacokinetics and drug-likeness using SwissADME. Simulating gastrointestinal digestion showed a recovery of 43.07% and 35.92% bioaccessibility. The protein banding patterns showed the presence of prolamin (57 kDa) and glutelin (12 kDa) as the predominant proteins in the NPC. The in silico hydrolysis predicts the presence of three and two peptide ligands in glutelin and prolamin fraction, respectively, with high affinity for PPARγ (≤160). Finally, the docking studies suggest that the prolamin-derived peptides QSPVF and QPY (−6.38 & −5.61 kcal/mol, respectively) have expected affinity and pharmacokinetic properties to act as potential PPARγ antagonists. Hence, according to our results, bioactive peptides resulting from NPC rice consumption might have an antiadipogenic effect via PPARγ interactions, but further experimentation and validation in suitable biological model systems are necessary to gain more insight and to provide evidence to support our in silico findings.

Nutraceuticals: A Promising Therapeutic Approach in Ophthalmology

Oxidative stress represents one of the main factors driving the pathophysiology of multiple ophthalmic conditions including presbyopia, cataracts, dry eye disease (DED), glaucoma, age-related macular degeneration (AMD) and diabetic retinopathy (DR). Currently, different studies have demonstrated the role of orally administered nutraceuticals in these diseases. For instance, they have demonstrated to improve lens accommodation in presbyopia, reduce protein aggregation in cataracts, ameliorate tear film stability, break up time, and tear production in dry eye, and participate in the avoidance of retinal neuronal damage and a decrease in intraocular pressure in glaucoma, contribute to the delayed progression of AMD, or in the prevention or treatment of neuronal death in diabetic retinopathy. In this review, we summarized the nutraceuticals which have presented a positive impact in ocular disorders, emphasizing the clinical assays. The characteristics of the different types of nutraceuticals are specified along with the nutraceutical concentration used to achieve a therapeutic outcome in ocular diseases.

Health effects of peptides obtained from hydrolysed chicken by-products by the action of Bromelia pinguin and B. karatas proteases in Wistar rats induced with metabolic syndrome

Metabolic syndrome (MS) is considered a major public health problem because it is associated with the development of cardiovascular disease and type 2 diabetes. Bioactive peptides can play an important role in the prevention and treatment of MS. The possible health effects of peptides obtained from hydrolysed chicken by-products (CH) by the action of plant proteases from Bromelia pinguin (BP), B. karatas (BK), and bromelain (BRO) were evaluated in a model of induced MS. Thirty male Wistar rats were randomised into the following groups: (1) standard diet (STD); (2) induction of MS with a hypercaloric diet (MS+CH); (3) CH-BP 200 mg CH/kg; (4) CH-BK 200 mg CH/kg; (5) CH-BRO 200 mg CH/kg; and (6) carnosine (CAR) 50 mg of carnosine/kg of body weight. The CH decreased the glucose levels (p < 0.05) and improved the lipid profile (p < 0.05) in the serum of the groups with induced MS. Liver lesions were attenuated with a decrease in hepatic enzymatic activities (p < 0.05), and the accumulation of lipid inclusions in the liver decreased. The data showed that CH and the use of proteases to obtain peptides with health effects could be a good therapeutic alternative for individuals with MS.

Switch off/switch on of a cysteinyl protease as a way to preserve the active catalytic group by modification with a reversible covalent thiol modifier: Immobilization of ficin on vinyl-sulfone activated supports

The immobilization of ficin (a cysteinyl proteases) on vinyl sulfone agarose produced its almost full inactivation. It was observed that the incubation of the free and immobilized enzyme in β-mercaptoethanol produced a 20 % of enzyme activity recovery, suggesting that the inactivation due to the immobilization could be a consequence of the modification of the catalytic Cys. To prevent the enzyme inactivation during the immobilization, switching off of ficin via Cys reaction with dipyridyl-disulfide was implemented, giving a reversible disulfide bond that produced a fully inactive enzyme. The switch on of ficin activity was implemented by incubation in 1 M β-mercaptoethanol. Using this strategy to immobilize the enzyme on vinyl sulfone agarose beads, the expressed activity of the immobilized ficin could be boosted up to 80 %. The immobilized enzyme presented a thermal stabilization similar to that obtained using ficin-glyoxyl-agarose beads. This procedure may be extended to many enzymes containing critical Cys, to permit their immobilization or chemical modification.

Dietary-Nutraceutical Properties of Oat Protein and Peptides

Oats are considered the healthiest grain due to their high content of phytochemicals, dietary fibers, and protein. In recent years, oat protein and peptides have gained popularity as possible therapeutic or nutraceutical candidates. Generally, oat peptides with bioactive properties can be obtained by the enzymatic hydrolysis of proteins and are known to have a variety of regulatory functions. This review article focused on the nutraceutical worth of oat proteins and peptides and also describes the application of oat protein as a functional ingredient. Outcomes of this study indicated that oat protein and peptides present various therapeutical properties, including antidiabetic, antioxidant, antihypoxic, antihypertensive, antithrombotic, antifatigue, immunomodulatory, and hypocholestrolaemic. However, most of the conducted studies are limited to in vitro conditions and less data is available on assessing the effectiveness of the oat peptides in vivo. Future efforts should be directed at performing systematic animal studies; in addition, clinical trials also need to be conducted to fully support the development of functional food products, nutraceutical, and therapeutical applications.

Plant-derived proteins as a sustainable source of bioactive peptides: recent research updates on emerging production methods, bioactivities, and potential application

The development of novel protein sources to compensate for the expected future shortage of traditional animal proteins due to their high carbon footprint is a major contemporary challenge in the agri-food industry currently. Therefore, both industry and consumers are placing a greater emphasis on plant proteins as a sustainable source of protein to meet the growing nutritional demand of ever increasing population. In addition to being key alternatives, many plant-based foods have biological properties that make them potentially functional or health-promoting foods, particularly physiologically active peptides and proteins accounting for most of these properties. This review discusses the importance of plant-based protein as a viable and sustainable alternative to animal proteins. The current advances in plant protein isolation and production and characterization of bioactive hydrolysates and peptides from plant proteins are described comprehensively. Furthermore, the recent research on bioactivities and bioavailability of plant protein-derived bioactive peptides is reviewed briefly. The limitations of using bioactive peptides, regulatory criteria, and the possible future applications of plant protein-derived bioactive peptides are highlighted. This review may help understand plant proteins and their bioactive peptides and provide valuable suggestions for future research and applications in the food industry.

Conventional and in silico approaches to select promising food-derived bioactive peptides: A review

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Seaweed and edible insects are considered new sources of bioactive peptides.

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Conventional approaches are necessary to validate the bioactivity of peptides.

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Bioinformatics tools accelerate the obtaining of bioactive peptides.

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The integrated approach is a promising strategy to obtain bioactive peptides.

The interest for food-derived bioactive peptides, either from common or unconventional sources, has increased due to their potential therapeutic effect against a wide range of diseases. The study of such bioactive peptides using conventional methods is a long journey, expensive and time-consuming. Hence, bioinformatic approaches, which can not only help to predict the formation of bioactive peptides from any known protein source, but also to analyze the protein structure/function relationship, have gained a new meaning in this scientific field. Therefore, this review aims to provides an overview of conventional characterization methods and the most recent advances in the field of in silico approaches for predicting and screening promising food-derived bioactive peptides.

Exploration of Dipeptidyl Peptidase-IV (DPP-IV) Inhibitory Peptides from Silkworm Pupae (Bombyx mori) Proteins Based on In Silico and In Vitro Assessments

This study aimed at exploring dipeptidyl peptidase-IV (DPP-IV) inhibitory peptides from silkworm pupae proteins by in silico analysis and in vitro assessments. In silico analysis of 274 silkworm pupae proteomes indicated that DPP-IV inhibitory peptides can be released from silkworm pupae proteins. In vitro assessments revealed that pepsin and bromelain led to better production of DPP-IV inhibitory peptides from silkworm pupae protein. Notably, peptide fractions (<1 kDa) from pepsin- and bromelain-treated hydrolysates exhibited more potent DPP-IV inhibitory activities. Two novel DPP-IV inhibitory peptides (Leu-Pro-Pro-Glu-His-Asp-Trp-Arg and Leu-Pro-Ala-Val-Thr-Ile-Arg) were identified by LC-MS/MS with IC₅₀ values of 261.17 and 192.47 μM, respectively. Enzyme kinetics data demonstrated that these two peptides displayed a mixed-type DPP-IV inhibition mode, which was further validated by molecular docking data. Overall, in silico analysis combined with in vitro assessments can serve as an effective and rapid approach for discovery of DPP-IV peptides from silkworm pupae proteins.

Production of Plant Proteases and New Biotechnological Applications: An Updated Review

An updated review of emerging plant proteases with potential biotechnological application is presented. Plant proteases show comparable or even greater performance than animal or microbial proteases for by-product valorization through hydrolysis for, for example, cheese whey, bird feathers, collagen, keratinous materials, gelatin, fish protein, and soy protein. Active biopeptides can be obtained as high added value products, which have shown numerous beneficial effects on human health. Plant proteases can also be used for wastewater treatment. The production of new plant proteases is encouraged for the following advantages: low cost of isolation using simple procedures, remarkable stability over a wide range of operating conditions (temperature, pH, salinity, and organic solvents), substantial affinity to a broad variety of substrates, and possibility of immobilization. Vegetable proteases have enormous application potential for the valorization of industrial waste and its conversion into products with high added value through low-cost processes.

Investigation of the interaction of a papain-like cysteine protease (RD19c) with selenium-binding protein 1 (SBP1) in Arabidopsis thaliana

AtRD19c is a member of the papain-like cysteine proteases known for its participation in anther development after its maturation by βVPE (vacuolar processing enzyme). This papain-like cysteine protease was identified as an interacting protein of AtSBP1 (selenium binding protein 1) in a yeast two-hybrid screening. To confirm this interaction, we studied AtRD19c with respect to its expression and ability to interact with AtSBP1. The highest gene expression levels of AtRD19c were observed in the roots of 10-day-old seedlings, whereas minimum levels appeared in the hypocotyls of 10-day-old seedlings and flowers. AtRD19c expression was upregulated by selenium, and analysis of its promoter activity showed colocalization of a reporter gene (GUS) with AtSBP1. Additionally, the AtRD19c expression pattern was upregulated in the presence of selenite, indicating its participation in the Se response network. Confocal fluorescence microscopy revealed that AtRD19c localizes in the root tip, lateral roots, and leaf trichomes. Finally, we confirmed the physical interaction between AtRD19c and AtSBP1 and showed the importance of the first 175 aa of the AtSBP1 polypeptide in this interaction. Importantly, the AtRD19c-AtSBP1 interaction was also demonstrated in planta by employing bimolecular fluorescent complementation (BiFC) in a protoplast system.

Exploring the DPP-IV Inhibitory, Antioxidant and Antibacterial Potential of Ovine "Scotta" Hydrolysates

The aim of this work was to valorize the by-product derived from the ricotta cheese process (scotta). In this study, ovine scotta was concentrated by ultrafiltration and then subjected to enzymatic hydrolyses using proteases of both vegetable (4% E:S, 4 h, 50 °C) and animal origin (4% E:S, 4 h, 40 °C). The DPP-IV inhibitory, antioxidant, and antibacterial activities of hydrolysates from bromelain (BSPH) and pancreatin (PSPH) were measured in vitro. Both the obtained hydrolysates showed a significantly higher DPP-IV inhibitory activity compared to the control. In particular, BSPH proved to be more effective than PSPH (IC₅₀ 8.5 ± 0.2 vs. 13 ± 1 mg mL⁻¹). Moreover, BSPH showed the best antioxidant power, while PSPH was more able to produce low-MW peptides. BSPH and PSPH hydrolysates showed a variable but slightly inhibitory effect depending on the species or strain of bacteria tested. BSPH and PSPH samples were separated by gel permeation chromatography (GPC). LC-MS/MS analysis of selected GPC fractions allowed identification of differential peptides. Among the peptides 388 were more abundant in BSPH than in the CTRL groups, 667 were more abundant in the PSPH group compared to CTRL, and 97 and 75 of them contained sequences with a reported biological activity, respectively.

A novel angiotensin-converting enzyme inhibitory peptide from rabbit meat protein hydrolysate: identification, molecular mechanism, and antihypertensive effect in vivo

Bioactive peptides exhibiting angiotensin-converting enzyme (ACE) inhibitory effects and extracted from natural foods have potential as healthy and safe therapeutics for high blood pressure. The aim of this study was to isolate and purify ACE inhibitory peptides from rabbit meat protein hydrolysate, to explore the underlying mechanisms by molecular docking, and to evaluate the antihypertensive effects in vivo. A novel ACE inhibitory tetrapeptide Trp-Gly-Ala-Pro (WGAP) was identified and purified from a bromelain hydrolysate. WGAP acted against ACE in a non-competitive manner with an IC₅₀ of 140.70 ± 4.51 μM. It was resistant to enzymatic degradation by pepsin and trypsin in vitro. Molecular docking analysis indicated that WGAP formed stable hydrogen bonds with ACE residues His353, Ala354 and ALA356. In vivo, 100 mg kg^-1 WGAP significantly reduced systolic and diastolic blood pressure in hypertensive rats by up to 42.66 ± 2.87 and 28.56 ± 2.71 mmHg, respectively, 4 h after oral administration. ACE inhibitory peptides derived from rabbit meat have potential antihypertensive effects and provide a new route for the exploration of novel hypertension inhibitors and the utilization of rabbit meat.

Characterization of the fruit proteolytic system of Bromelia serra Griseb. (Bromeliaceae) and its application in bioactive peptides release

A crude extract with proteolytic activity was prepared from edible fruits of Bromelia serra, containing cysteine peptidases with molecular masses between 24.1 and 25.9 kDa. The extract presented an optimal pH range of 6.03-9.05, retained more than 80% of activity after thermal pre-treatments at 23, 37, and 45°C (120 min), but it was rapidly inactivated after 10 min at 75°C. These proteases were employed to hydrolyze soybean proteins, bovine casein and bovine whey, achieving degrees of hydrolysis of 18.3 ± 0.6, 29.1 ± 0.7, and 12.6 ± 0.9% (55°C, 180 min), respectively. The casein 180 min-hydrolysate (55°C) presented the maximum value of antioxidant activity (2.89 ± 0.12 mg/mL Trolox), and the whey protein 180 min-hydrolysate (55°C) showed the highest percentage of angiotensin-converting enzyme inhibition (91.9 ± 1.2%). This low-cost enzymatic preparation would be promising for the food industry because it requires mild working conditions and yields hydrolysates with biological activities useful as ingredients for functional food. PRACTICAL APPLICATION: Proteolytic enzymes are employed in the food industry in a wide variety of processes since they modify the properties of proteins causing beneficial effects such as improvement digestibility, diminution of allergenicity, and release of bioactive peptides. Fruits from Bromelia serra possess cysteine peptidases that could be used in food biotechnology because they are capable to hydrolyze soybean and milk proteins by mild working conditions and to provoke the release of bioactive peptides. These hydrolysates containing antioxidative and ACE-inhibitor activities would be useful as ingredients for functional foods or as nutraceuticals, which are nowadays two products highly required by consumers.

Potential Biological Activities of Peptides Generated during Casein Proteolysis by Curly Kale (Brassica oleracea L. var. sabellica L.) Leaf Extract: An In Silico Preliminary Study

This study is a brief report on the proteolytic activity of curly kale leaf extract against casein. Casein degradation products and an in silico analysis of the biological activity of the peptides obtained was performed. The efficiency of casein hydrolysis by curly kale extract was determined using SDS-PAGE and by peptide concentration determination. The pattern of the enzymatic activity was determined by MALDI-TOF MS analysis. The results showed that α- and β-casein were more resistant to curly kale extract hydrolysis, whereas κ-casein was absent in the protein profile after 8 h of proteolysis, and all casein fractions were completely hydrolyzed after 24 h of incubation. Based on sequence analysis, seven peptides were identified, with molecular mass in the range of 1151-3024 Da. All the peptides were products of β-casein hydrolysis. The identified amino acid sequences were analyzed in BIOPEP, MBPDB, and FeptideDB databases in order to detect the potential activities of the peptides. In silico analysis suggests that the β-casein-derived peptides possess sequences of peptides with ACE inhibitory, antioxidant, dipeptidyl peptidase IV inhibitory, antithrombotic, immunomodulatory, and antiamnesic bioactivity. Our study was first to evaluate the possibility of applying curly kale leaf extract to generate biopeptides through β-casein hydrolysis.

Debittering effect of partially purified proteases from soybean seedlings on soybean protein isolate hydrolysate produced by alcalase

To explore the potential application of proteases from soybean seedlings in the debittering of soybean protein hydrolysates, soybean seeds were germinated from 1 to 10 days. It was found that the sixth day seedlings exhibited highest proteases activity (130 U/g). After partial purification, the activity of proteases (PSP) from the sixth day seedlings further increased to 2675 U/g. In addition, PSP exhibited maximum activity at 50 ℃ and pH 5.5, and mainly comprised of two proteins with the molecular weight of 64.57 and 25.12 kDa respectively. PSP could decrease the bitterness score of the soybean protein isolate hydrolysate (SPIH) produced by Alcalase 2.4L from 3.45 to 0 in 3 h. Meanwhile, the degree of hydrolysis of SPIH slightly increased from 11.87% to 15.61% without reducing the antioxidant activity. This study may provide a solution to the contradiction between removing the bitterness of soybean protein hydrolysates and maintaining the bioactivity.

Endopeptidases, exopeptidases, and glutamate decarboxylase in soybean water extract and their in vitro activity

The proteolytic activity of some soybean endogenous proteases have been clarified in the previous studies, but the information concerning the roles of these proteases and some other unknown ones during soybean processing are scarce. Herein, 16 endopeptidases, 13 exopeptidases, 24 inhibitors (two serpin-ZX and one subtilisin inhibitor firstly identified), and one glutamate decarboxylase were identified in the soybean water extract by the liquid chromatography tandem mass spectrometry analysis. Amongst the identified endopeptidases, just the aspartic endopeptidases (optimal at pH 2.5-3 and 35-45 °C) showed the detectable proteolytic activity by the tricine-sodium dodecyl sulphate-polyacrylamide gel electrophoresis and protease inhibitor assay analyses, whereas serine, cysteine, and metallo- endopeptidases (except P34 probable thiol protease) did not. Free amino acid analysis showed that the exopeptidases and glutamate decarboxylase were optimal at pH 6 and 45 °C, and by 6 h incubation, the free amino acids and γ-aminobutyric acid almost doubled.

Current findings support the potential use of bioactive peptides in enhancing zinc absorption in humans

More than two billion people around the world are affected by zinc deficiency, mainly due to the inadequate intake and absorption of zinc. Based on recent research findings, the bioactive peptides could potentially be used to combat zinc deficiency particularly due to their Zinc chelating ability. The main aim of this review was to present current findings, supporting the potential use of bioactive peptides based on their ability to enhance zinc absorption. In-vivo, in-vitro, and ex-vivo studies have demonstrated that zinc chelating peptides can enhance the retention, transportation, and absorption of zinc. Comparative studies on zinc bioavailability from protein hydrolysates and zinc salts have demonstrated that the protein hydrolysates-zinc complexes are more bioavailable than the zinc salts. Data from the structure-function relationship of zinc chelating peptides suggest that the zinc chelating capacities of peptides increase in the following order; the position of zinc chelator > zinc chelator strength > abundance of zinc chelators > net charge > molecular weight. In addition, the transport mechanism of peptide-zinc complex is hypothesized, and the potential use of bioactive peptides based on their safety and taste and limitations to their commercialization are also discussed.

Production of ACE Inhibitory Peptides from Whey Proteins Modified by High Intensity Ultrasound Using Bromelain

High Intensity Ultrasound (HIUS) can induce modification of the protein structure. The combination of enzymatic hydrolysis and ultrasound is an interesting strategy to improve the release of the Angiotensin-Converting Enzyme (ACE) inhibitory peptides. In this study, whey proteins were pretreated with HIUS at two levels of amplitude (30 and 50%) for 10 min, followed by hydrolysis using the vegetable protease bromelain. The hydrolysates obtained were ultrafiltrated and their fractions were submitted to a simulated gastrointestinal digestion. The conformational changes induced by HIUS on whey proteins were analyzed using Fourier-transform infrared spectroscopy by attenuated total reflectance (FTIR-ATR) and intrinsic spectroscopy. It was found that both levels of ultrasound pretreatment significantly decreased the IC₅₀ value (50% Inhibitory Concentration) of the hydrolysates in comparison with the control (α = 0.05). After this treatment, HIUS-treated fractions were shown as smaller in size and fractions between 1 and 3 kDa displayed the highest ACE inhibition activity. HIUS promoted significant changes in whey protein structure, inducing, unfolding, and aggregation, decreasing the content of α-helix, and increasing β-sheets structures. These findings prove that ultrasound treatment before enzymatic hydrolysis is an innovative and useful strategy that modifies the peptide profile of whey protein hydrolysates and enhances the production of ACE inhibitory peptides.

Soybean proteins/peptides: A review on their importance, biosynthesis, vacuolar sorting, and accumulation in seeds

Soybean is one of the most important sources of plant protein and is known for its wide range of agricultural, food, and industrial applications as well as health benefits. Interest in soybean proteins has been steadily growing as progressively more applications and benefits are discovered. This review article is focused on the major seed storage proteins of soybean, their three-dimensional structures, their nutritional importance and bioactive peptides, cellular synthesis, and accumulation in seeds. This will also summarize past efforts in the recombinant production of foreign proteins or bioactive peptides in soybean seed.

Immobilization of papain: A review

Papain is a cysteine protease from papaya, with many applications due to its broad specificity. This paper reviews for first time the immobilization of papain on different supports (organic, inorganic or hybrid supports) presenting some of the features of the utilized immobilization strategies (e.g., epoxide, glutaraldehyde, genipin, glyoxyl for covalent immobilization). Special focus is placed on the preparation of magnetic biocatalysts, which will permit the simple recovery of the biocatalyst even if the medium is a suspension. Problems specific to the immobilization of proteases (e.g., steric problems when hydrolyzing large proteins) are also defined. The benefits of a proper immobilization (enzyme stabilization, widening of the operation window) are discussed, together with some artifacts that may suggest an enzyme stabilization that may be unrelated to enzyme rigidification.

Bioactive peptides from fisheries residues: A review of use of papain in proteolysis reactions

Papain is a cysteine endopeptidase of vegetal origin (papaya (Carica papaya L.) with diverse applications in food technology. In this review we have focused our attention on its application in the production of bio-peptides by hydrolysis of proteins from fish residues. This way, a residual material, that can become a contaminant if dumped without control, is converted into highly interesting products. The main bioactivity of the produced peptides is their antioxidant activity, followed by their nutritional and functional activities, but peptides with many other bioactivities have been produced. Thera are also examples of production of hydrolysates with several bioactivities. The enzyme may be used alone, or in combination with other enzymes to increase the degree of hydrolysis.