Crystallization and preliminary X-ray analysis of four cysteine proteases from Ficus carica latex

Changes in ficin specificity by different substrate proteins promoted by enzyme immobilization

Ficin extract has been immobilized using different supports: glyoxyl and Aspartic/1,6 hexamethylenediamine (Asp/HA) agarose beads. The latter was later submitted to glutaraldehyde modification to get covalent immobilization. The activities of these 3 kinds of biocatalysts were compared utilizing 4 different substrates, casein, hemoglobin and bovine serum albumin and benzoyl-arginine-p-nitroanilide at pH 7 and 5. Using glyoxyl-agarose, the effect of enzyme-support reaction time on the activity versus the four substrates at both pH values was studied. Reaction time has been shown to distort the enzyme due to an increase in the number of covalent support-enzyme bonds. Surprisingly, for all the substrates and conditions the prolongation of the enzyme-support reaction did not imply a decrease in enzyme activity. Using the Asp/HA supports (with different amount of HA) differences in the effect on enzyme activity versus the different substrates are much more significant, while with some substrates the immobilization produced a decrease in enzyme activity, with in other cases the activity increased. These different effects are even increased after glutaraldehyde treatment. That way, the conformational changes induced by the biocatalyst immobilization or the chemical modification fully altered the enzyme protein specificity. This may also have some implications when following enzyme inactivation.

Plant and Arthropod IgE-Binding Papain-like Cysteine Proteases: Multiple Contributions to Allergenicity

Papain-like cysteine proteases are widespread and can be detected in all domains of life. They share structural and enzymatic properties with the group's namesake member, papain. They show a broad range of protein substrates and are involved in several biological processes. These proteases are widely exploited for food, pharmaceutical, chemical and cosmetic biotechnological applications. However, some of them are known to cause allergic reactions. In this context, the objective of this review is to report an overview of some general properties of papain-like cysteine proteases and to highlight their contributions to allergy reactions observed in humans. For instance, the literature shows that their proteolytic activity can cause an increase in tissue permeability, which favours the crossing of allergens through the skin, intestinal and respiratory barriers. The observation that allergy to PLCPs is mostly detected for inhaled proteins is in line with the reports describing mite homologs, such as Der p 1 and Der f 1, as major allergens showing a frequent correlation between sensitisation and clinical allergic reactions. In contrast, the plant food homologs are often digested in the gastrointestinal tract. Therefore, they only rarely can cause allergic reactions in humans. Accordingly, they are reported mainly as a cause of occupational diseases.

Comparative Analysis of the Immune Response and the Clinical Allergic Reaction to Papain-like Cysteine Proteases from Fig, Kiwifruit, Papaya, Pineapple and Mites in an Italian Population

Several plant papain-like cysteine proteases are exploited by the food, cosmetic, pharmaceutical and textile industries. However, some of these enzymes can cause allergic reactions. In this context, we investigated the frequency of sensitization and allergic reactions to some fruit and/or latex cysteine proteases, which are used as additives by the food industry to improve and modify the quality of their products. The FABER test was used to analyse the patients' sensitization towards five plants and, for comparison, two homologous mite cysteine proteases. In an Italian population of 341 allergic patients, 133 (39%) had IgE specific for at least one of the seven cysteine proteases under investigation. Most of the patients were IgE positive for Der p 1 and/or Der f 1 (96.38%) reported a clinical history suggestive of respiratory allergy to mites, whereas none of the subjects sensitized to the homologs from papaya, pineapple and fig reported allergy symptoms following ingestion of these foods. Only one patient referred symptoms from ingesting kiwifruit. Therefore, the obtained results showed that sensitization to the fruit enzymes was only rarely concomitant with allergic reactions. These observations, together with the literature reports, suggest that the allergy to plant papain-like cysteine proteases might mainly be an occupational disease.

Next-generation nutraceuticals: bioactive peptides from plant proteases

Bioactive peptides are short and specific fragments of proteins with a wide range of biological activities that provide health benefits to the host. These natural peptides are safe and nontoxic and do not show any side effects. Nowadays, the production and characterization of bioactive peptides have been a key area of research as they show great potential as nutraceuticals and functional foods. Thus, bioactive peptides are considered next-generation therapeutic agents that can replace pharmaceutical products with profound adverse effects in the near future. So far, proteolytic hydrolysis has been used as the method of choice for the large-scale production of bioactive peptides. Studies have reported that peptides with specific characteristics can be generated using a particular type of protease. Microbial proteases are the predominantly used ones because of the ease in their production and purification. However, recently, plant proteases have gained a renewed interest as they offer diversity and better specificity compared with other proteases. This review highlights the potential of plant proteases for the production of bioactive peptides and also describes the benefits of bioactive peptides as nutraceuticals.

Efficacy of Ficus sycomorus (Sycamore Fig) Extract on Intestinal Coccidiosis in Experimentally Infected Rabbits

This study was conducted to investigate the effect of the Ficus sycomorus extract on Eimeria intestinalis in experimentally infected rabbits. For this purpose, forty male 30-day-old rabbits (Blanc de Bouscat) were divided into four groups (n = 10 in each group). Rabbits kept in the first group served as negative control (non-treated-non-infected). Rabbits kept in the second, third, and fourth groups were challenged at 10 weeks old with 3 × 10⁴E. intestinalis sporulated oocysts. The third and fourth groups were treated orally with diclazuril 10% (0.05 mg/kg body weight) and F. sycomorus (100 mg/Kg) for three consecutive days, respectively. The efficacy was assessed based on the growth performance parameters, clinical symptoms, oocyst shedding, histopathological findings, and hematological parameters for 16 days post challenge. The study revealed that rabbits treated with F. sycomorus methanolic extract and diclazuril showed mild clinical symptoms with a significant decrease in oocyst shedding compared with the positive control. Moreover, the diclazuril-treated group showed the highest leukocytic count and the lowest monocytes percentage compared with other groups. Furthermore, the lowest lymphocytes percentage was recorded in the control positive group. Histopathologically, moderate coccidia infestation in the intestinal mucosa and moderate hydropic degeneration of hepatocytes were observed in the diclazuril treated group compared with the negative control. However, mild coccidia infestation in the intestinal mucosa and slight coagulative necrosis of hepatocytes was found in the F. sycomorus treated group. In conclusion, F. sycomorus methanolic extract had promising effects on the live performance, oocyst count, and blood variables, while it possesses adverse consequences on the hepatic tissues. Further studies are required to optimize the dose and extraction method to mitigate its side effects.

Potential applications of ficin in the production of traditional cheeses and protein hydrolysates

Using proteolytic enzymes extracted from plant materials is a promising way to ensure the sustainability of the food industry. This is particularly true for the dairy industry, especially in cheesemaking and the production of different milk protein hydrolysates for special food applications, particularly nutrition for infants, older adults, and people with food allergies. Ficin, a cysteyl protease isolated from the latex of the fig tree (Ficus carica), is characterized by strong enzymatic activity and can be used for milk clotting and protein hydrolysis for application in different foods. In particular, it can be used for milk protein hydrolysis to produce ingredients with reduced or eliminated allergenicity and improved bioavailability. Ficin can also be used as an active and effective replacement for calf rennet in cheesemaking, such as in traditional Cacioricotta and Teleme cheeses. It can also be used to produce protein hydrolysates with low or no allergenicity for application in infant formula and geriatric nutrition. This work provides an overview of ficin, a plant-derived protease, with an emphasis on its potential application in the production of some traditional cheeses and milk protein hydrolysates for special food applications.

Thrombin- and plasmin-like and platelet-aggregation-inducing activities of Plumeria alba L. latex: Action of cysteine protease

ETHNOPHARMACOLOGICAL RELEVANCE

In folk medicine, parts of Plumeria alba L. are used for the treatment of many diseases, with its latex being used for curing skin diseases and promoting wound healing.

AIM OF THE STUDY

This study aimed to study the role of P. alba L. latex in hemostasis and platelet aggregation.

MATERIALS AND METHODS

The latex of P. alba L. was processed to remove waxes and enrich protein content, and the final extract was named Plumeria alba L. natant latex (PaNL). PaNL was analyzed for protease activity against casein. The type of protease in PaNL was identified by using protease inhibitors such as E-64, phenylmethylsulfonyl fluoride, ethylenediaminetetraacetic acid, and pepstatin A. Human fibrinogen, fibrin, and collagen types I and IV were subjected to hydrolysis with different concentrations of PaNL. The thrombin-like activity of PaNL was determined by analyzing its fibrinogen-clotting and procoagulant activities. The role of PaNL in platelet aggregation was also investigated. Its hemorrhagic and edema-inducing activities were evaluated in a mouse model. Phytochemical compounds were identified by gas chromatography-mass spectroscopy.

RESULTS

The findings of casein/gelatin zymography confirmed that PaNL possesses protease activity. The results of the protease inhibition study indicated the presence of a cysteine-type protease(s) in PaNL. PaNL hydrolyzed the subunits of fibrinogen, fibrin, and collagen types I and IV. Its fibrin-degradation activity indicated that PaNL possesses plasmin-like activity. PaNL induced clotting of citrated human plasma within 3 min of incubation in the absence of CaCl_2, indicating the presence of thrombin-like activity, which was further confirmed by the results of the fibrinogen-clotting assay. PaNL induced platelet aggregation in the absence of agonists. There was no hemolytic activity. Mice injected with PaNL did not show edema/ hemorrhagic activity.

CONCLUSION

PaNL possesses procoagulant, fibrino(geno)lytic, thrombin- and plasmin-like activities and induces platelet aggregation, which could explain its usage for wound treatment in folk medicine.

Biochemical Properties and Anti-Biofilm Activity of Chitosan-Immobilized Papain

Chitosan, the product of chitin deacetylation, is an excellent candidate for enzyme immobilization purposes. Here we demonstrate that papain, an endolytic cysteine protease (EC: 3.4.22.2) from Carica papaya latex immobilized on the matrixes of medium molecular (200 kDa) and high molecular (350 kDa) weight chitosans exhibits anti-biofilm activity and increases the antimicrobials efficiency against biofilm-embedded bacteria. Immobilization in glycine buffer (pH 9.0) allowed adsorption up to 30% of the total protein (mg g chitosan⁻¹) and specific activity (U mg protein⁻¹), leading to the preservation of more than 90% of the initial total activity (U mL⁻¹). While optimal pH and temperature of the immobilized papain did not change, the immobilized enzyme exhibited elevated thermal stability and 6–7-fold longer half-life time in comparison with the soluble papain. While one-half of the total enzyme dissociates from both carriers in 24 h, this property could be used for wound-dressing materials design with dosed release of the enzyme to overcome the relatively high cytotoxicity of soluble papain. Our results indicate that both soluble and immobilized papain efficiently destroy biofilms formed by Staphylococcus aureus and Staphylococcus epidermidis. As a consequence, papain, both soluble and immobilized on medium molecular weight chitosan, is capable of potentiating the efficacy of antimicrobials against biofilm-embedded Staphylococci. Thus, papain immobilized on medium molecular weight chitosan appears a presumably beneficial agent for outer wound treatment for biofilms destruction, increasing antimicrobial treatment effectiveness.

Isolation, identification, and stability of Ficin 1c isoform from fig latex

Purified alkaline ficin isoform, identified as Ficin 1c regarding fig transcriptome, shows decreased stability compared to the ficin isoform mixture.

The proteolytic system of pineapple stems revisited: Purification and characterization of multiple catalytically active forms

Crude pineapple proteases extract (aka stem bromelain; EC 3.4.22.4) is an important proteolytic mixture that contains enzymes belonging to the cysteine proteases of the papain family. Numerous studies have been reported aiming at the fractionation and characterization of the many molecular species present in the extract, but more efforts are still required to obtain sufficient quantities of the various purified protease forms for detailed physicochemical, enzymatic and structural characterization. In this work, we describe an efficient strategy towards the purification of at least eight enzymatic forms. Thus, following rapid fractionation on a SP-Sepharose FF column, two sub-populations with proteolytic activity were obtained: the unbound (termed acidic) and bound (termed basic) bromelain fractions. Following reversible modification with monomethoxypolyethylene glycol (mPEG), both fractions were further separated on Q-Sepharose FF and SP-Sepharose FF, respectively. This procedure yielded highly purified molecular species, all titrating ca. 1 mol of thiol group per mole of enzyme, with distinct biochemical properties. N-terminal sequencing allowed identifying at least eight forms with proteolytic activity. The basic fraction contained previously identified species, i.e. basic bromelain forms 1 and 2, ananain forms 1 and 2, and comosain (MEROPS identifier: C01.027). Furthermore, a new proteolytic species, showing similarities with basic bomelain forms 1 and 2, was discovered and termed bromelain form 3. The two remaining species were found in the acidic bromelain fraction and were arbitrarily named acidic bromelain forms 1 and 2. Both, acidic bromelain forms 1, 2 and basic bromelain forms 1, 2 and 3 are glycosylated, while ananain forms 1 and 2, and comosain are not. The eight protease forms display different amidase activities against the various substrates tested, namely small synthetic chromogenic compounds (DL-BAPNA and Boc-Ala-Ala-Gly-pNA), fluorogenic compounds (like Boc-Gln-Ala-Arg-AMC, Z-Arg-Arg-AMC and Z-Phe-Arg-AMC), and proteins (azocasein and azoalbumin), suggesting a specific organization of their catalytic residues. All forms are completely inhibited by specific cysteine and cysteine/serine protease inhibitors, but not by specific serine and aspartic protease inhibitors, with the sole exception of pepstatin A that significantly affects acidic bromelain forms 1 and 2. For all eight protease forms, inhibition is also observed with 1,10-phenanthrolin, a metalloprotease inhibitor. Metal ions (i.e. Mn²⁺, Mg²⁺ and Ca²⁺) showed various effects depending on the protease under consideration, but all of them are totally inhibited in the presence of Zn²⁺. Mass spectrometry analyses revealed that all forms have a molecular mass of ca. 24 kDa, which is characteristic of enzymes belonging to the papain-like proteases family. Far-UV CD spectra analysis further supported this analysis. Interestingly, secondary structure calculation proves to be highly reproducible for all cysteine proteases of the papain family tested so far (this work; see also Azarkan et al., 2011; Baeyens-Volant et al., 2015) and thus can be used as a test for rapid identification of the classical papain fold.

Autolysis control and structural changes of purified ficin from Iranian fig latex with synthetic inhibitors

The fig's ficin is a cysteine endoproteolytic enzyme, which plays fundamental roles in many plant physiological processes, and has many applications in different industries such as pharmaceutical and food. In this work, we report the inhibition and activation of autolysis and structural changes associated with reaction of ficin with iodoacetamide and tetrathionate using high-performance liquid chromatography (HPLC), ultra filtration membrane, and dynamic light scattering (DLS) methods. The ficin structural changes were also determined using UV-absorption, circular dichroism (CD), fluorescence spectroscopy, and differential scanning calorimetry (DSC) techniques. These techniques demonstrated that iodoacetamide completely inhibited ficin autolysis, which was irreversible. However, tetrathionate partially and reversibility inhibited its autolysis. The ficin structural changes with two synthetic inhibitors were associated with secondary structural changes related to decreased alpha-helix and increased beta sheet and random coil conformations, contributing to its aggregation.