Native and Biotechnologically Engineered Plant Proteases with Industrial Applications

Revolutionizing protein hydrolysis in wastewater: Innovative immobilization of metagenome-derived protease in periodic mesoporous organosilica with imidazolium framework

This research focused on utilizing periodic mesoporous organosilica with imidazolium framework (PMO-IL), to immobilize a metagenome-sourced protease (PersiProtease1), thereby enhancing its functional efficiency and catalytic effectiveness in processing primary proteins found in tannery wastewater. The successful immobilization of enzyme was confirmed through the use of N2 adsorption-desorption experiment, XRD, FTIR, TEM, FESEM, EDS and elemental analytical techniques. The immobilized enzyme exhibited greater stability in the presence of various metal ions and inhibitors compared to its free form. Furthermore, enzyme binding to PMO-IL nanoparticles (NPs) reduced leaching, evidenced by only 11.41 % of enzyme leakage following a 120-min incubation at 80 °C and 6.99 % after 240 min at 25 °C. Additionally, PersiPro@PMO-IL maintained impressive operational consistency, preserving 62.24 % of its activity over 20 cycles. It also demonstrated notable stability under saline conditions, with an increase of 1.5 times compared to the free enzyme in the presence of 5 M NaCl. The rate of collagen hydrolysis by the immobilized protease was 46.82 % after a 15-minute incubation at 60 °C and marginally decreased to 39.02 % after 20 cycles indicative of sustained efficacy without significant leaching throughout the cycles. These findings underscore the effectiveness of PMO-IL NPs as a viable candidate for treating wastewater containing protein.

Enzymes for production of whey protein hydrolysates and other value-added products

Whey is a byproduct of dairy industries, the aqueous portion which separates from cheese during the coagulation of milk. It represents approximately 85-95% of milk's volume and retains much of its nutrients, including functional proteins and peptides, lipids, lactose, minerals, and vitamins. Due to its composition, mainly proteins and lactose, it can be considered a raw material for value-added products. Whey-derived products are often used to supplement food, as they have shown several physiological effects on the body. Whey protein hydrolysates are reported to have different activities, including antihypertensive, antioxidant, antithrombotic, opioid, antimicrobial, cytomodulatory, and immuno-modulatory. On the other hand, galactooligosaccharides obtained from lactose can be used as prebiotic for beneficial microorganisms for the human gastrointestinal tract. All these compounds can be obtained through physicochemical, microbial, or enzymatic treatments. Particularly, enzymatic processes have the advantage of being highly selective, more stable than chemical transformations, and less polluting, making that the global enzyme market grow at accelerated rates. The sources and different products associated with the most used enzymes are particularly highlighted in this review. Moreover, we discuss metagenomics as a tool to identify novel proteolytic enzymes, from both cultivable and uncultivable microorganisms, which are expected to have new interesting activities. Finally enzymes for the transformation of whey sugar are reviewed. In this sense, carbozymes with ß-galactosidase activity are capable of lactose hydrolysis, to obtain free monomers, and transgalactosylation for prebiotics production. KEY POINTS: • Whey can be used to obtain value-added products efficiently through enzymatic treatments • Proteases transform whey proteins into biopeptides with physiological activities • Lactose can be transformed into prebiotic compounds using ß-galactosidases.

Proteases: Importance, Immobilization Protocols, Potential of Activated Carbon as Support, and the Importance of Modifying Supports for Immobilization

Although enzymes have been used for thousands of years, their application in industrial processes has gained importance since the 20th century due to technological and scientific advances in several areas, including biochemistry [...].

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.

Proteolytic Activity of Silkworm Thorn (Cudrania tricuspidata) Fruit for Enzymatic Hydrolysis of Food Proteins

This study aimed to isolate the proteolytic fraction from the silkworm thorn fruit (Cudrania tricuspidata) through ethanol precipitation at different ratios, and to determine its proteolytic activity and optimal activity conditions. Furthermore, the hydrolysis characteristics and antioxidant activity of soy protein isolate (SPI) and whey protein concentrate (WPC) hydrolyzates obtained through the enzymatic hydrolysis of freeze-dried silkworm thorn fruit powder (SF) were evaluated. For isolation and partial purification of proteolytic fraction, the water-solubilized fraction of the silkworm thorn fruit was purified through ethanol precipitation at four different ratios of 1:1, 1:2, 1:4, and 1:6 (v/v). The protein recovery rate, caseinolytic activity, protein pattern, and optimal activity (pH, temperature, and inhibitors) of fractional ethanol precipitate obtained from the silkworm thorn fruit (ESF) were evaluated. The proteolytic fraction obtained from silkworm thorn fruit exhibited a major protein band around 65-70 kDa and showed the highest proteolytic activity at a 1:4 ratio of ethanol precipitation (p < 0.05). The optimal activity of the measured enzyme fraction was determined to be at pH 9.0 and 50 °C, and the proteolytic activity of ESF was almost inhibited by phenyl methyl sulphonyl fluoride (PMSF, 2 mM), a serine protease inhibitor. Compared to Alcalase and papain, extensively used as commercial enzymes, the silkworm thorn fruit powder was less effective in hydrolyzing SPI and WPC. Nevertheless, SPI and WPC hydrolyzates mediated with silkworm thorn fruit powder showed even better antioxidant activities than those mediated with Alcalase and papain. Thus, our results show the potential application of silkworm thorn fruit as a novel source of plant protease for producing human-grade protein hydrolyzates.

Strawberry Protease as a Laundry Detergent Additive Candidate: Immobilization, Compatibility Study with Detergent Ingredients, and Washing Performance Test

The potential of strawberry-derived protease as a component of laundry detergent is investigated. The compatibility of the enzyme with various surfactants, oxidizing agents, and commercial detergents is tested. The immobilized enzyme prepared by immobilizing Co2+ ions together with the enzyme is also tested. Strawberry crude protease shows high stability in the presence of surfactants frequently used in detergents. The enzyme is found to be relatively stable to oxidizing agents. In addition, it is determined that strawberry protease works in excellent compatibility with different commercial solid and liquid detergents in the Turkish market and also maintains its stability very well. Washing tests based on visual examination also reveal that the enzyme improves the washing performance of the tested detergent. All these properties and high activity at alkaline pH make this enzyme a very strong candidate for use in laundry detergent formulations.

Efficient three phase partitioning of actinidin from kiwifruit (Actinidia deliciosa) and its characterization

Three phase partitioning (TPP) method was effectively utilized for the extraction and purification of milk clotting protease (actinidin) from the kiwifruit pulp. The different purification parameters of TPP such as ammonium sulfate saturation, ratio of the crude kiwifruit extract to tert-butanol, and the pH value of extract were optimized. The 40% (w/v) salt saturation having 1.0:0.75 (v/v) ratio of crude kiwifruit extract to tert-butanol at 6.0 pH value exhibited 3.14 purification fold along with 142.27% recovery, and the protease was concentrated exclusively at intermediate phase (IP). This fraction showed milk-clotting activity (MCA), but there was no such activity in lower aqueous phase (AP). The enzyme molecular weight was found to be 24 kDa from Tricine SDS-PAGE analysis. Recovered protease demonstrated greater stability at pH 7.0 and temperature 50 °C. The Vmax and Km values were 121.9 U/ml and 3.2 mg/ml respectively. Its cysteine nature was demonstrated by inhibition studies. This study highlighted that the TPP is an economic and effective method for extraction and purification of actinidin from kiwifruit, and it could be used as a vegetable coagulant for cheesemaking.

Multi-Enzyme Supplementation to Diets Containing 2 Protein Levels Affects Intramuscular Fat Content in Muscle and Modulates Cecal Microflora Without Affecting the Growth Performance of Finishing Pigs

We investigated the effects of crude protein (CP) levels and exogenous enzymes on growth performance, meat quality, toxic gas emissions, and colonic microbiota community in 200 finishing pigs. Four groups corresponded to 4 diets: 16.74% CP (high-protein level, HP) and 14.73% CP (medium protein level, MP) diet supplemented with or without 1-g/kg multi-enzymes (ENZs, including 1000-U/kg protease, 2500-U/kg α-amylase, and 10,000-U/kg β-glucanase), using a 2 × 2 factorial arrangement. After 7 weeks of trial, ENZs supplementation increased (P < 0.05) the average daily gain (ADG) of finishing pigs during weeks 4 to 7 and in the overall period and improved gross energy utilization. Dietary HP improved (P < 0.05) ADG during the overall period. The MP diet-treated pigs had higher intramuscular fat (IMF) content in the longissimus dorsi muscle (P < 0.01). ENZs supplementation to the MP diets lowered muscle IMF content (P < 0.01). Additionally, pigs fed the HP diet released (P < 0.05) more NH3 and H2S in excrement. The HP diet enhanced (P < 0.05) intestinal microbial richness, represented by higher observed_ amplicon sequence variants and Chao1. Administration of ENZs to the HP diet increased (P < 0.05) the Shannon and Pielou's evenness. Dietary MP promoted Firmicutes proliferation. Supplementary HP diet increased the relative abundances of Spirochaetota, Verrucomicrobiota, Desulfobacterota, and Fibrobacterota (P < 0.05). Supplemental ENZ elevated (P < 0.05) Actinobacteriota and Desulfobacterota abundances. ENZ supplementation to the HP diet increased the abundances of Bacteroidota, Desulfobacterota, and Proteobacteria but lowered their abundances in the MP diet. Taken together, the HP diet or ENZs' supplements improved growth performance. Although the interaction between CP levels and ENZs had no effect on growth performance, it modulated colonic flora and muscle IMF content.

Clotting and Proteolytic Activity of Freeze-Dried Crude Extracts Obtained from Wild Thistles Cynara humilis L. and Onopordum platylepis Murb

The rising interest in finding alternatives to animal rennet in cheese production has led to studying the technological feasibility of using and exploiting new species of herbaceous plants. In this research work, and for the first time, freeze-dried extracts from Cynara humilis L. (CH) and Onopordum platylepis Murb. (OP) were studied for mineral and protein content, and their clotting and proteolytic activity were compared to those of Cynara cardunculus L. (CC). The effect of extract concentration (5-40 mg extract/mL), temperature (20-85 °C), pH (5-8), and CaCl₂ concentration (5-70 mM) on the milk clotting activity (MCA) of CC, CH and OP extracts was evaluated. The MCA values were significantly higher in CC at the same extract concentration. The extract that showed the most significant increase in clotting activity due to increased temperature was OP, with maximum activity at 70 °C. The pH value for maximum milk clotting was 5.0 for both CC and CH, whereas, in the case of OP, the pH value was 5.5. CaCl₂ enhanced the clotting capacity of the extracts, particularly for OP and CH. Furthermore, proteolytic activity (PA) and the hydrolysis rate increased with increasing time and enzyme concentration, with CC being the extract that achieved the highest caseinolytic activity.

Exogenous protease supplementation to the diet enhances growth performance, improves nitrogen utilization, and reduces stress in finishing pigs

We have conducted this experiment to evaluate a new exogenous protease in finishing pigs' growth performance, nutrient digestibility, gas emission, blood profiles, and meat quality. A total of 200 pigs of 52.15 ± 2.31 kg average body weight (BW) were divided into four dietary treatments named as: CON, basal diet; TRT1, basal diet + 0.05% protease; TRT2, basal diet + 0.1% protease; TRT3, basal diet + 1.5% protease. Each treatment consisted of 10 pens, where five pigs were allotted to each pen according to their body weight and sex. The dietary treatments were allotted to the pens in a randomized block design. During this 10-week-long experiment, BW, average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio (G:F) were calculated for Week 0-5, Week 6-10, and the overall period. During Week 6-10, ADG was higher in TRT2 and TRT3 than in the CON and TRT1 groups. At the same time, a linear increase was observed in ADG and G:F of the pigs. In addition, the final BW of pigs' was linearly increased by protease supplementation. On Week 10, there was a linear trend of increase (p = 0.0575) in crude protein digestibility and a trend of linear reduction (p = 0.0651) in NH₃ gas emission. In blood profile, cortisol presented a linear decrease in both Week 5 (p = 0.251) and Week 10 (p = 0.0585). In addition, increasing doses of protease showed a trend of linear increase (p = 0.0592) in creatinine, whereas linear reduction was observed in the concentration of epinephrine (p = 0.0636) and norepinephrine (p = 0.0167) during Week 10. In conclusion, protease supplementation helped in improving daily gain in finishing pigs through protein digestibility with associated reduction of ammonia emission and blood stress hormones.

Sequencing and de novo transcriptome assembly for discovering regulators of gene expression in Jack (Artocarpus heterophyllus)

Jack (Artocarpus heterophyllus) is a multipurpose fruit-tree species with minimal genomic resources. The study reports developing comprehensive transcriptome data containing 80,411 unigenes with an N50 value of 1265 bp. We predicted 64,215 CDSs from the unigenes and annotated and functionally categorized them into the biological process (23,230), molecular function (27,149), and cellular components (17,284). From 80,411 unigenes, we discovered 16,853 perfect SSRs with 192 distinct repeat motif types reiterating 4 to 22 times. Besides, we identified 2741 TFs from 69 TF families, 53 miRNAs from 19 conserved miRNA families, 25,953 potential lncRNAs, and placed three functional eTMs in different lncRNA-miRNA pairs. The regulatory networks involving genes, TFs, and miRNAs identified several regulatory and regulated nodes providing insight into miRNAs' gene associations and transcription factor-mediated regulation. The comparison of expression patterns of some selected miRNAs vis-à-vis their corresponding target genes showed an inverse relationship indicating the possible miRNA-mediated regulation of the genes.

Latex peptidases produce peptides capable of delaying fungal growth in bread

Antimicrobial peptides (AMPs) have been reported to be promising alternatives to chemical preservatives. Thus, this study aimed to characterise AMPs generated from the hydrolysis of wheat gluten proteins using latex peptidases of Calotropis procera, Cryptostegia grandiflora, and Carica papaya. The three hydrolysates (obtained after 16 h at 37 °C, using a 1: 25 enzyme:  substrate ratio) inhibited the growth of Aspergillus niger, A. chevalieri, Trichoderma reesei, Pythium oligandrum, Penicillium sp., and Lasiodiplodia sp. by 60-90%, and delayed fungal growth on bread by 3 days when used at 0.3 g/kg. Moreover, the specific volume and expansion factor of bread were not affected by the hydrolysates. Of 28 peptides identified, four were synthesised and exhibited activity against Penicillium sp. Fluorescence and scanning electron microscopy suggested that the peptides damaged the fungal plasma membrane. Bioinformatics analysis showed that no peptide was toxic and that the antigenic ones had cleavage sites for trypsin or pepsin.

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.

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.

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.

Collagenase Activity of Bromelain Immobilized at Gold Nanoparticle Interfaces for Therapeutic Applications

Bromelain (Bro) is a multiprotein complex extracted from the pineapple plant Ananas comosus, composed of at least eight cysteine proteases. Bro has a wide range of applications in medicine and industry, where the stability of its active proteases is always a major concern. The present study describes the improvement of stability and gain of specific activity in the enzymatic content of Bro immobilized on gold nanoparticles (GNPs). GNPs were synthesized in situ using Bro as the reducing and stabilizing agents and characterized by surface plasmon resonance and transmission electron microscopy. Consistent with the structural changes observed by circular dichroism analysis, the association with GNPs affected enzyme activity. The active Bro immobilized on GNPs (NanoBro) remained stable under storage and gained thermal stability consistent with a thermophilic enzyme. Proteolytic assays were performed on type I collagen membranes using fluorescence spectroscopy of O-phthaldialdehyde (OPA), changes in the membrane superficial structure, and topography by scanning electron microscopy, FTIR, and scanning laser confocal microscopy. Another characteristic of the NanoBro observed was the significant increase in susceptibility to the inhibitory effect of E-64, indicating a gain in cysteine protease activity. The higher stability and specific activity of NanoBro contributed to the broadening and improvement of Bro applications.

Camel Milk-Clotting Using Plant Extracts as a Substitute to Commercial Rennet

The transformation of camel milk into cheese is an operation considered very delicate because of several difficulties encountered in achieving coagulation. The present study aims to improve coagulation abilities of camel milk using enzyme extracts from pineapple, kiwi, and ginger. Our results concerning the characterization of the enzymatic extract showed an extraction yield that varies according to the type of extract (pineapple: 75.28% ± 4.59, kiwi: 63.97% ± 5.22, and ginger: 28.64% ± 1.47). The optimum coagulation conditions of the 3 types of extract were as follows: for pineapple: pH = 5 and temperature = 45°C; for kiwifruit: pH = 6.6 and temperature = 40°C; and for ginger: pH = 6.6 and temperature = 45°C. A fresh cheese was made from camel milk with a particular nutritional quality and consistency. The kiwi proteases displayed chymosin-like properties and thus hold the best potential for use as a milk coagulant in cheese production.

An insight into artisanal leather making in Ghana

Abstract

The production of leather from animal skins and hides through tanning processes began in the pre-historic ages. Despite the origination of new leather making techniques such as chrome tanning which is being employed extensively today, the traditional method of leather production primarily through vegetable tanning is still being practised mostly in artisanal tanneries in developing nations including Ghana. Artisanal leather making, thus, contributes beneficially to rural livelihood. Nevertheless, the growth of this sector has been stifled by the lack of innovative technologies to enhance productivity. This challenge could be partly linked to the knowledge gap on the scientific principles governing artisanal leather production processes. This study, therefore, elaborates on various process steps and materials employed in traditional leather making in Ghana and the scientific principles underlying each of the processes. It also makes a comparison between traditional and modern leather manufacturing processes and identifies knowledge and technological gaps which would inspire in-depth scientific research into artisanal leather making.

Graphical abstract

Exploring the Milk-Clotting and Proteolytic Activities in Different Tissues of Vallesia glabra: a New Source of Plant Proteolytic Enzymes

Proteolytic enzymes are widely distributed in nature, playing essential roles in important biological functions. Recently, the use of plant proteases at the industrial level has mainly increased in the food industry (e.g., cheesemaking, meat tenderizing, and protein hydrolysate production). Current technological and scientific advances in the detection and characterization of proteolytic enzymes have encouraged the search for new natural sources. Thus, this work aimed to explore the milk-clotting and proteolytic properties of different tissues of Vallesia glabra. Aqueous extracts from the leaves, fruits, and seeds of V. glabra presented different protein profiles, proteolytic activity, and milk-clotting activity. The milk-clotting activity increased with temperature (30-65 °C), but this activity was higher in leaf (0.20 MCU/mL) compared with that in fruit and seed extracts (0.12 and 0.11 MCU/mL, respectively) at 50 °C. Proteolytic activity in the extracts assayed at different pH (2.5-12.0) suggested the presence of different types of active proteases, with maximum activity at acidic conditions (4.0-4.5). Inhibitory studies indicated that major activity in V. glabra extracts is related to cysteine proteases; however, the presence of serine, aspartic, and metalloproteases was also evident. The hydrolytic profile of caseins indicated that V. glabra leaves could be used as a rennet substitute in cheesemaking, representing a new and promising source of proteolytic enzymes.

Production and Characterization of Antioxidative Hydrolysates and Peptides from Corn Gluten Meal Using Papain, Ficin, and Bromelain

There has been a growing interest in developing natural antioxidants with high efficiency and low cost. Bioactive protein hydrolysates could be a potential source of natural and safer antioxidants. The objectives of this study were to hydrolyze corn gluten meal using three plant-derived proteases, namely papain, ficin, and bromelain, to produce antioxidative hydrolysates and peptides and to characterize the antioxidant performances using both chemical assays and a ground meat model. The optimum hydrolysis time for papain was 3 h, and for ficin and bromelain was 4 h. The hydrolysates were further separated by sequential ultrafiltration to 5 hydrolysate fractions named F1 to F5 from low molecular weight (MW) (<1 kDa) to high MW range (>10 kDa), which were further characterized for TPC, free radical scavenging capacity against DPPH and ABTS, and metal chelating activity. The fraction F4 produced by papain (CH-P4), F1 produced by ficin (CH-F1), and F3 produced by bromelain (CH-B3) showed the strongest antioxidant activity and yield, respectively. These three fractions were incorporated into ground pork to determine their inhibition effects on lipid oxidation during a 16-day storage period. The inhibition effect was enhanced with the addition of higher amount of hydrolysate (e.g., 1000 vs. 500 mg/kg). The CH-P4 reduced lipid oxidation in ground meat by as much as 30.45%, and CH-B3 reduced oxidation by 27.2% at the same level, but the inhibition was only 13.83% with 1000 mg/kg of CH-F1. The study demonstrated that CGM protein hydrolysates and peptides could be used as naturally derived antioxidant in retarding lipid oxidation and improving product storage stability.

Manufacture of fresh cheese using east African Calotropis procera leaves extract crude enzyme as milk coagulant

The present work was aimed to develop fresh cheese using the crude extract from calotropis procera leaves and thereby performed evaluating milk-clotting activity and acute toxicity of crude extract. The extraction of coagulant was performed at 30, 45, and 60℃ using 2, 6, and 10 g of dried calotropis procera leaves, respectively. The highest yield of crude enzyme extract was acquired with 2 g and 30℃, and results were varied significantly (p < .05). The highest cheese yield and fastest clotting time were 17.89 kg cheese/100kg milk and 14:50 min acquired with 10 g C. procera powder at 60℃ extraction temperature, respectively. E. coli, total bacterial count, yeast, and mold microbial load detection were observed below the limit established by codex alimentarius. This study recommends that use of C. procera crude enzyme leaves extract can be used as alternate milk coagulant for production of fresh cheeses. Soft cheeses manufactured with calotropin enzyme as milk coagulant revealed no adverse effects of toxicity tested on albino rates to the highest dose.

Biocatalysis in the winemaking industry: Challenges and opportunities for immobilized enzymes

Enzymes are powerful catalysts already being used in a large number of industrial processes. Impressive advantages in enzyme catalysts improvement have occurred in recent years aiming to improve their performance under harsh operation conditions far away from those of their cellular habitat. Production levels of the winemaking industry have experienced a remarkable increase, and technological innovations have been introduced for increasing the efficiency at different process steps or for improving wine quality, which is a key issue in this industry. Enzymes, such as pectinases and proteases, have been traditionally used, and others, such as glycosidases, have been more recently introduced in the modern wine industry, and many dedicated studies refer to the improvement of enzyme performance under winemaking conditions. Within this framework, a thorough review on the role of enzymes in winemaking is presented, with special emphasis on the use of immobilized enzymes as a significant strategy for catalyst improvement within an industry in which enzymes play important roles that are to be reinforced paralleling innovation.

Plant Aspartic Proteases for Industrial Applications: Thistle Get Better

Plant proteases have a number of applications in industrial processes including cheese manufacturing. The flower of the cardoon plant (Cynara cardunculus L.) is traditionally used as a milk-clotting agent in protected designation of origin cheeses made from goat and sheep milk. Plant-derived rennets are of particular importance to consumers who wish to eat cheeses that are produced without harming any animals. In this review, we have highlighted the importance of plant proteases, particularly aspartic proteases, in industrial processes, as well as exploring more fundamental aspects of their synthesis. We have also reviewed and discussed the production of these enzymes using sustainable and cost-effective alternative platforms.

Identification, characterization, and antifungal activity of cysteine peptidases from Calotropis procera latex

Cysteine peptidases (EC 3.4.22) are the most abundant enzymes in latex fluids. However, their physiological functions are still poorly understood, mainly related to defense against phytopathogens. The present study reports the cDNA cloning and sequencing of five undescribed cysteine peptidases from Calotropis procera (Aiton) Dryand (Apocynaceae) as well as some in silico analyses. Of these, three cysteine peptidases (CpCP1, CpCP2, and CpCP3) were purified. Their enzymatic kinetics were determined and they were assayed for their efficacy in inhibiting the hyphal growth of phytopathogenic fungi. The mechanism of action was investigated by fluorescence and atomic force microscopy as well as by induction of reactive oxygen species (ROS). The deduced amino acid sequences showed similar biochemical characteristics and high sequence homology with several other papain-like cysteine peptidases. Three-dimensional models showed two typical cysteine peptidase domains (L and R domains), forming a "V-shaped" active site containing the catalytic triad (Cys, His, and Asn). Proteolysis of CpCP1 was higher at pH 7.0, whereas for CpCP2 and CpCP3 it was higher at 7.5. All peptidases exhibited optimum activity at 35 °C and followed Michaelis-Menten kinetics. However, the major difference among them was that CpCP1 exhibited highest V_max, K_m, K_cat and catalytic efficiency. All peptidases were deleterious to the two fungi tested, with IC₅₀ of around 50 μg/mL. The peptidases promoted membrane permeabilization, morphological changes with leakage of cellular content, and induction of ROS in F. oxysporum spores. These results corroborate the hypothesis that latex cysteine peptidases play a role in defense against fungi.

Plant Proteases: From Key Enzymes in Germination to Allies for Fighting Human Gluten-Related Disorders

Plant proteases play a crucial role in many different biological processes along the plant life cycle. One of the most determinant stages in which proteases are key protagonists is the plant germination through the hydrolysis and mobilization of other proteins accumulated in seeds and cereal grains. The most represented proteases in charge of this are the cysteine proteases group, including the C1A family known as papain-like and the C13 family also called legumains. In cereal species such as wheat, oat or rye, gluten is a very complex mixture of grain storage proteins, which may affect the health of sensitive consumers like celiac patients. Since gluten proteins are suitable targets for plant proteases, the knowledge of the proteases involved in storage protein mobilization could be employed to manipulate the amount of gluten in the grain. Some proteases have been previously found to exhibit promising properties for their application in the degradation of known toxic peptides from gluten. To explore the variability in gluten-degrading capacities, we have now analyzed the degradation of gluten from different wheat cultivars using several cysteine proteases from barley. The wide variability showed highlights the possibility to select the protease with the highest potential to alter grain composition reducing the gluten content. Consequently, new avenues could be explored combining genetic manipulation of proteolytic processes with silencing techniques to be used as biotechnological tools against gluten-related disorders.

Influence of low-protein diets and protease and bromelain supplementation on growth performance, nutrient digestibility, blood urine nitrogen, creatinine, and faecal noxious gas in growing–finishing pigs

A total of 180 crossbred pigs [(Landrace × Yorkshire) × Duroc] with an average body weight of 22.61 ± 1.23 kg were used in an 18 wk study to determine the effect of protease and bromelain in low-protein diets in grower–finisher pigs. Dietary treatments included: T1, basal diet treatment; T2, low-protein treatment; T3 (T2 + 0.2 g kg−1 protease); and T4 (T2 + 0.3 g kg−1 bromelain). Pigs fed protease- and bromelain-supplemented diets increased average daily gain and gain to feed ratio at week 18, dry matter and nitrogen digestibility at week 6, as well as energy digestibility at week 12, compared with low-protein diet (P < 0.05). Pigs fed T3 and T4 diets led to a trend of decreased (P < 0.05) blood urine nitrogen (BUN) and creatinine concentrations at the 12th wk. A reduction of ammonia (NH3) and hydrogen sulfide (H2S) emission was observed in pigs fed the dietary protease and bromelain supplementation at the 6th wk (P < 0.05). There was no effect on all parameters between the protease and bromelain supplementation treatments. In conclusion, supplementation of protease and bromelain to low-protein diet enhanced growth performance, nutrient digestibility, and reduced NH3 and H2S in growing–finishing pigs.

Discovery of digestive enzymes in carnivorous plants with focus on proteases

BACKGROUND

Carnivorous plants have been fascinating researchers with their unique characters and bioinspired applications. These include medicinal trait of some carnivorous plants with potentials for pharmaceutical industry.

METHODS

This review will cover recent progress based on current studies on digestive enzymes secreted by different genera of carnivorous plants: Drosera (sundews), Dionaea (Venus flytrap), Nepenthes (tropical pitcher plants), Sarracenia (North American pitcher plants), Cephalotus (Australian pitcher plants), Genlisea (corkscrew plants), and Utricularia (bladderworts).

RESULTS

Since the discovery of secreted protease nepenthesin in Nepenthes pitcher, digestive enzymes from carnivorous plants have been the focus of many studies. Recent genomics approaches have accelerated digestive enzyme discovery. Furthermore, the advancement in recombinant technology and protein purification helped in the identification and characterisation of enzymes in carnivorous plants.

DISCUSSION

These different aspects will be described and discussed in this review with focus on the role of secreted plant proteases and their potential industrial applications.

The evidence of proteases in sprouted seeds and their application for animal protein digestion

It has been experimentally proven that germinated plant seeds, such as leek, red clover, broccoli, and others contain proteases, which are able to digest animal protein such as gelatin, bovine albumin, casein, and egg albumin. Preliminary tests were carried out with the use of a semi-qualitative gelatin test, which is often applied to prove the presence of fruit enzymes. Quantitative examinations were carried out with the use of a ninhydrin reaction for amino acid determination as well as the Bradford and Smith methods for protein determination. Respective calibration curves were obtained for glycine (amino acid analysis) as well as for egg albumin, bovine albumin, and gelatin (protein analysis), with a full statistical evaluation including Mandel and Lack-of-Fit tests to check for linearity. It has been proven that the selected germinated seeds containing proteases can be applied as an effective aid for animal protein digestion.

Antiacanthain A: New proteases isolated from Bromelia antiacantha Bertol. (Bromeliaceae)

Crude extract (CE) from pulp of Bromelia antiacantha Bertol. mature fruit, contains at least 3 cysteine proteases with proteolytic activity. By single step cation exchange chromatography (Hi-trap SP-HP) of partially purified CE, the protease with the lowest pI, Antiacanthain A (AntA), was isolated. It showed maximum activity at pH9, and 75% of remaining activity was maintained over a wide pH range (pH6-10). The AntA activity exhibits a constant increase up to 70°C. Maintains almost 100% of its activity at 45 at pH6 and 9. A 60% of AntA was active by titration with specific inhibitor, E64. Amidasic activity was studied with pyroglutamyl-phenyl-leucyl-paranitroaniline (PFLNA) substrate having higher AntA catalytic efficiency of (k_cat/K_m=470s^-1M^-1) relative to stem bromelain (k_cat/K_m=305s^-1M^-1). Esterase activity using p-nitrophenyl esters of N-α-CBZ-l-Lysine (z-L-LysONp) showed a 10-fold higher catalytic efficiency for AntA (k_cat/K_m=6376s^-1M^-1) relative to stem bromelain (k_cat/K_m=688s^-1M^-1). Incubation with 8M Urea did not affect AntA activity and remained unchanged for 18h, with 6M GndHCl resulted in a 41% decrease in activity after 30min incubation, maintained this activity 18h. AntA exhibits high sequence identity with proteases of the Bromeliaceae family.

Expression, activation and processing of a novel plant milk-clotting aspartic protease in Pichia pastoris

Galium verum, also known as Lady's Bedstraw or Cheese Rennet, is an herbaceous perennial plant traditionally used in cheese-making. We used RACE PCR to isolate novel enzymes from Galium verum with the ability to clot milk. This approach generated two cDNA sequences (named preprogaline A and B) encoding proteins displaying the typical plant aspartic protease primary structure. Preprogaline B was expressed in the yeast Pichia pastoris, after deleting and replacing its original signal peptide with the yeast α-factor signal peptide from Saccharomyces cerevisiae. The secreted recombinant protein was obtained by growing P. pastoris in YPD medium and had the ability to clot milk. The mature form of progaline B is a heterodimeric glycosylated enzyme, with a molecular weight of approximately 48 kDa, that contains a heavy (30.7 kDa) and a light (13.5 kDa) polypeptide chains linked by disulfide bonds. Western blot analysis revealed that progaline B is activated by the acidification of the yeast culture medium and that enzymatic activation requires two steps. First the precursor protein is cleaved into two polypeptide chains by partial removal of the plant-specific insert (PSI) present in plant aspartic proteases; this is later followed by propeptide removal. By altering the pH of the P. pastoris culture medium, we were able to obtain either active or inactive forms of the enzyme. Recombinant progaline B displayed a κ-casein hydrolysis pattern analogous to those produced by the animal and microbial coagulants currently used in the dairy industry, but it exhibited a different digestion profile on α- and β-caseins. The plant protease progaline B displays milk-clotting activities suitable for the production of novel dairy products.

Trends and Prospects of Plant Proteases in Therapeutics

The main function of proteases in any living organism is the cleavage of proteins resulting in the degradation of damaged, misfolded and potentially harmful proteins and therefore providing the cell with amino acids essential for the synthesis of new proteins. Besides this main function, proteases may play an important role as signal molecules and participate in numerous protein cascades to maintain the vital processes of an organism. Plant proteases are no exception to this rule. Moreover, in contrast to humanencoded enzymes, many plant proteases possess exceptional features such as higher stability, unique substrate specificity and a wide pH range for enzymatic activity. These valuable features make plant-derived proteolytic enzymes suitable for many biomedical applications, and furthermore, the plants can serve as factories for protein production. Plant proteases are already applied in the treatment of several pathological conditions in the human organism. Some of the enzymes possess antitumour, antibacterial and antifungal activity. The collagenolytic activity of plant proteases determines important medical applications such as the healing of wounds and burn debridement. Plant proteases may affect blood coagulation processes and can be applied in the treatment of digestive disorders. The present review summarizes recent advances and possible applications for plant proteases in biomedicine, and proposes further development of plant-derived proteolytic enzymes in the biotechnology and pharmaceutical industries.