Bromelain enzymes

Isolation of Proteolytic Enzyme from Pineapple Crown

The pineapple waste from the pineapple industry has contributed to an increase in waste in Malaysia and worldwide every year. A major type of endopeptidase enzymes found in pineapple is fruit bromelain, stem bromelain, ananain, and comasain. This study aims to extract and purify protease from the crown of MD2 pineapple. Protease was extracted and purified using anion exchange chromatography, gel filtration, and desalting before being identified using liquid chromatography-mass spectrometry (LC-MS). Proteolytic activity was determined using the well diffusion method and Casein Digestion Unit. In the present study, the proteolytic assay showed that 1 kg crown of MD2 cultivar produced an activity of 126.0 ± 3.86 U/ml, a specific activity of 3937.50 U/mg. In the present study, the proteolytic assay showed that 1 kg crown of MD2 cultivar produced an activity of 126.0 ± 3.86 U/mL, a specific activity of 3937.50 U/mg and the total activity of 3.94 × 109 U. The molecular weight of the purified enzyme was in the range of 25 to 35 kDa under the optimum condition of pH 7 and 37°C. Purification of the extract yielded a band at the molecular weight of 20–25 kDa at the optimum pH of 3 and 9 at 60°C. From LC-MS analysis, the purified enzyme from the crown extract was similar to ananain under accession number A0A199VSS3 (according to Uniprot). It had five unique peptides and covered 97/356 amino acids (44.9% coverage). The ananain (EC 3.4.22.31) is classified in the subfamilies of cysteine protease C1A (clan CA, family C1), a peptidase family related to papain. In conclusion, protease was extracted and identified as an ananain-like protease from the crown.

Glucose-Induced Enhanced Virulence in Strains of Multidrug-Resistant Pseudomonas aeruginosa Isolated from Diabetic Patients

Pseudomonas aeruginosa is known for its metabolic versatility and uses a variety of substrates; interestingly, glucose is not the favored carbon source. Although glucose is not readily utilized by them, there is a possibility that the increased susceptibility of diabetics to infections with P. aeruginosa is related to the effect of glucose on the expression of virulence genes. The curiosity in understanding the effect of glucose on virulence gene expression in P. aeruginosa and the lacuna of studies in this field prompted us to undertake the current investigation. It included the quantification of various virulence factors and their gene expression upon supplementation with glucose in clinical MDR P. aeruginosa isolates recovered from diabetics. Interestingly, the study observed a remarkable difference in the virulence attributes in the isolates with and without glucose supplementation. External glucose was found to be modulating the QS gene expression, thus altering the elaboration of other virulence factors. Variations in the gene expressions induced by glucose partly explain the increased susceptibility of diabetic patients to P. aeruginosa infections.

Unravelling the Distinctive Virulence Traits and Clonal Relationship among the Pseudomonas aeruginosa Isolates from Diabetic Patients

Infections with P. aeruginosa are three times more common in people with diabetes than in non-diabetic individuals. Investigations disclosing the distinguishing traits of P. aeruginosa strains to cause respiratory and wound infection in diabetics is limited. Wound swab and sputum from infected diabetic patients were used for the isolation of P. aeruginosa. The confirmed isolates were evaluated for their virulence factor production, antibiotic susceptibility, and clonal relationship. The study confirmed the increased virulence of sputum isolates characterized by their multidrug resistant nature, strong biofilm formation at 72h [(p<0.05) =0.003)] and 96h [(p<0.05) =0.002)] and elaboration of proteolytic enzymes (40.0%). Albeit the fact that wound isolates were less virulent than the sputum isolates, there was an increased siderophore production (77.0%). Nearly 90.0% of the isolates including sputum and wound were resistant to colistin. Random Amplified Polymorphic DNA analysis showed no distinct lineages of wound and sputum isolates. The study disclosed the higher prevalence of virulent P. aeruginosa in causing infection in the diabetics. No distinct lineages of the wound and sputum isolates indicated their ability to adapt to different host environments. To the best of our knowledge, this is the first study to show the difference in virulence traits among the P. aeruginosa strains isolated from sputum and wound of diabetic patients. Our study distinctly reveals the significance of periodic examination of antibiotic resistance and virulence factors of P. aeruginosa in order to recognize the possible co-regulatory mechanism involved in their expression.

Development of membranes based on carboxymethyl cellulose/acetylated arrowroot starch containing bromelain extract carried on nanoparticles and liposomes

Polymeric membranes have been used in several applications, including their use as curatives in cutaneous wounds. Bromelain has long been used for anti-inflammatory purposes, so the objective of this work was to produce carboxymethylcellulose-acetylated blends, incorporate bromelain, characterize the systems, compare the blends with bromelain loaded in nanoparticles and liposomes and, finally, to evaluate their healing potential. Four membrane formulations were produced by solvent evaporation: the control, membranes containing free bromelain, bromelain-loaded nanoparticles (NPs) and bromelain-loaded liposomes (LIPs). The enzyme concentration was the same for all formulations. Transparent, flexible and intact films were obtained. The membranes containing free bromelain, bromelain-loaded NPs and bromelain-loaded LIPs had higher water content, lower water vapor permeability and maximum tensile strength, and greater elongation at rupture. The capacity to absorb simulated exudate was higher in samples containing free bromelain, and bioadhesion was reduced in the presence of free bromelain compared to the control. An in vivo assay was performed to verify the membranes' healing potential. Histological analysis revealed no edema on the 14th day in animals treated with membranes containing bromelain-loaded NPs and LIPs.

Extraction and crosslinking of bromelain aggregates for improved stability and reusability from pineapple processing waste

The present study is first of its kind that focuses upon the extraction of bromelain from pineapple core waste and stabilising it as insoluble cross-linked aggregates. The influence of process variables such as the choice of precipitant, type of cross-linker, concentration of cross-linker and the reaction time for cross-linking step was investigated upon the activity recovery of bromelain cross-linked aggregates. The optimization of this biocatalyst preparation specifically recovered 87% of the enzymatic activity available in pineapple core waste by ammonium sulphate (60%, w/v) precipitation followed by cross-linking for 4 h with 80 mM glutaraldehyde. Cross-linked bromelain aggregates were thermally more stable and exhibited higher pH stability in comparison to free bromelain. The cross-linked bromelain aggregates exhibited higher operational stability in different organic solvents at 4 °C. The highest operational stability (% stability given in parenthesis) was observed in acetone (100%) followed by hexane (53.6%), ethyl acetate (39.6%), ethanol (32.5%) and chloroform (14.9%). The kinetic studies revealed higher Km value (5.45 mM) after the formation of cross-linked bromelain aggregates as compared to free bromelain (5.04 mM) with almost similar Vmax values. Cross-linked bromelain aggregates also showed significant reusability characteristics with an activity retention of >85% after 5-time cycles. Such recyclability of bromelain cross-linked aggregates could lead to potential industrial applications in both food and non-food sector. In addition, the present extraction method avoids costs related to purification and expensive immobilization carriers.

Performance of a Two-Stage Membrane System for Bromelain Separation from Pineapple Waste Mixture as Impacted by Enzymatic Pretreatment and Diafiltration

Membrane technology has been successfully applied for the purification of bromelain, a protease enzyme from pineapple. However, the current system operates less optimally in terms of flux and separation primarily due to properties of the feed, such as viscosity. Hence, in this study, enzymatic pretreatment and diafiltration operation were employed in a two-stage ultrafiltration (UF) system to enhance the performance of the purification and concentration process of bromelain enzyme from an extract of pineapple crude waste mixture (CWM). Pretreatment of the CWM extract using either pectinase or cellulase, or the combination of both, was applied and compared regarding the apparent viscosity reduction. Diafiltration step was introduced in UF stage 2 and observations on the flux performance, enzyme recovery and enzyme purity were made. A 12% apparent viscosity reduction was achieved when the CWM extract was pretreated with pectinase which led to 37-38% improvement in the flux performance of both UF stages, as well as higher enzyme recovery in UF stage 1. The introduction of diafiltration mode in UF stage 2 managed to sustain high flux values while yielding 4.4-fold enzyme purity (higher than a 2.5-fold purity achieved in our previous work); however, high diluent consumption was needed. The outcomes of this study showed that the flux performance and bromelain separation can be enhanced by reducing the viscosity with the employment of enzymatic pretreatment and diafiltration operation. Thus, both techniques can be potentially applied in a large-scale membrane-based process for bromelain production.

Chemo-Enzymatic Synthesis of Linear and Branched Cationic Peptides: Evaluation as Gene Carriers

Cationic peptides such as poly(l-lysine) and poly(l-arginine) are important tools for gene delivery since they can efficiently condense DNA. It is difficult to produce cationic peptides by recombinant bacterial expression, and its chemical synthesis requires several steps of protection/deprotection and toxic agents. Chemo-enzymatic synthesis of peptides is a clean chemistry technique that allows fast production under mild conditions. With the aim to simplify the production of cationic peptides, the present work develops an enzymatic reaction which enables the synthesis of linear cationic peptides and, through terminal functionalization with tris(2-aminoethyl)amine, of branched cationic peptide conjugates, which show improved DNA complex formation. Cytotoxicity and transfection efficiency of all the chemo-enzymatically synthesized cationic peptides are evaluated for their novel use as gene delivery agents. Synthesized peptides exhibit transfection efficiencies comparable to previously reported monodisperse peptides. Chemo-enzymatic synthesis opens the door for efficient production of cationic peptides for their use as gene delivery carriers.

Nanoparticles decorated with proteolytic enzymes, a promising strategy to overcome the mucus barrier

The intestinal mucus gel layer represents a stumbling block for drug adsorption. This study is aimed to formulate a nanoparticulate system able to overcome this barrier by cleaving locally the glycoprotein substructures of the mucus. Mucolytic enzymes such as papain (PAP) and bromelain (BRO) were covalently conjugated to poly(acrylic acid) (PAA). Nanoparticles (NPs) were then formulated via ionic gelation method and characterized by particle size, zeta potential, enzyme content and enzymatic activity. The NPs permeation quantified by rotating tube studies was correlated with changes in the mucus gel layer structure determined by pulsed-gradient-spin-echo NMR (PGSE-NMR), small-angle neutron scattering (SANS) and spin-echo SANS (SESANS). PAP and BRO functionalized NPs had an average size in the range of 250 and 285 nm and a zeta potential that ranged between -6 and -5 mV. The enzyme content was 242 μg enzyme/mg for PAP modified NPs and 253 μg enzyme/mg for BRO modified NPs. The maintained enzymatic activity was 43% for PAP decorated NPs and 76% for BRO decorated NPs. The rotating tube technique revealed a better performance of BRO decorated NPs compared to PAA decorated NPs, with a 4.8-fold higher concentration of NPs in the inner slice of mucus. Addition of 0.5 wt% of enzyme functionalized NPs to 5 wt% intestinal mucin led to c.a. 2-fold increase in the mobility of the mucin as measured by PGSE-NMR indicative of a significant break-up of the structure of the mucin. SANS and SESANS measurements further revealed a change in structure of the intestinal mucus induced by the incorporation of the functionalized NPs mostly occurring at a length scale longer than 0.5 μm. Accordingly, BRO decorated NPs show higher potential than PAP functionalized NPs as mucus permeating drug delivery systems.

Production of plant proteases in vivo and in vitro--a review

In the latest two decades, the interest received by plant proteases has increased significantly. Plant enzymes such as proteases are widely used in medicine and the food industry. Some proteases, like papain, bromelain and ficin are used in various processes such as brewing, meat softening, milk-clotting, cancer treatment, digestion and viral disorders. These enzymes can be obtained from their natural source or through in vitro cultures, in order to ensure a continuous source of plant enzymes. The focus of this review will be the production of plant proteases both in vivo and in vitro, with particular emphasis on the different types of commercially important plant proteases that have been isolated and characterized from naturally grown plants. In vitro approaches for the production of these proteases is also explored, focusing on the techniques that do not involve genetic transformation of the plants and the attempts that have been made in order to enhance the yield of the desired proteases.

Extraction of bromelain from pineapple peels

Large amount of pineapple peels (by-products) is left over after processing and they are a potential source for bromelain extraction. Distilled water (DI), DI containing cysteine and ethylenediaminetetraacetic acid (EDTA) (DI-CE), sodium phosphate buffer pH 7.0 (PB) and PB containing cysteine and EDTA (PB-CE) were used as extractants for bromelain from the pineapple peels. The highest bromelain activity was obtained when it was extracted with PB-CE (867 and 1032 units for Nang Lae and Phu Lae cultv, respectively). The PB could maintain the pH of the extract (pH 5.1-5.7) when compared with others. Under sodium dodecyl sulfate polyacrylamide gel electrophoresis, the extract showed protein bands in the range 24-28 kDa. The protein band with a molecular weight of ∼28 kDa exposed the clear zone on blue background under the casein-substrate gel electrophoresis. The effects of the bromelain extract on the protein patterns of beef, chicken and squid muscles were also determined. Trichloroacetic acid soluble peptide content of all the treated muscles increased when the amount of bromelain extract increased. Decrease in myosin heavy chains and actin was observed in all the muscle types when bromelain extract was used. The best extractant for bromelain from pineapple peels was PB-CE. Moreover, bromelain extract could be used as a muscle food tenderizing agent in food industries.

Purification and Characterization of a Pineapple Crown Leaf Thiol Protease

A thiol protease was isolated and purified from the crown leaf of pineapple, Ananas comosus (L.) Merr. cv. Queen, by an immunoaffinity procedure. After the purification to electrophoretic homogeneity, the enzyme was characterized with respect to some of its physico-chemical and kinetic properties. The molecular weight of the protease (22.4-22.9 kDa), Km (97 microM) and kcat (8.8 s(-1)) for its esterolytic cleavage of the synthetic protease substrate N(alpha)-CBZ-L-lysine p-nitrophenyl ester, the concentration of its thiol activator L-cysteine required for half maximal activation A0.5 (9.9 microM), optimum pH (6.5) for its proteolytic action on azocasein, T(1/2) (60 degrees C) for inactivation by heating the enzyme (35.5 microg protein/mL) in citrate buffer pH 6.0 for 15 min, and SH-group content (0.98 mol/mol enzyme) were determined. Most of these physicochemical and kinetic properties were found to be similar to those of the already well-characterized stem bromelain (EC 3.4.22.32). Thus, the immunoaffinity purified crown leaf protease appeared to be closely related to stem bromelain.

Procerain, a stable cysteine protease from the latex of Calotropis procera

A protease was purified to homogeneity from the latex of medicinal plant Calotropis procera (Family-Asclepiadaceae). The molecular mass and isoelectric point of the enzyme are 28.8 kDa and 9.32, respectively. Hydrolysis of azoalbumin by the enzyme was optimal in the range of pH 7.0-9.0 and temperature 55-60 degree C. The enzyme hydrolyses denatured natural substrates like casein, azoalbumin, and azocasein with high specific activity. Proteolytic and amidolytic activities of the enzyme were activated by thiol protease activators and inhibited by thiol protease inhibitors, indicating the enzyme to be a cysteine protease. The enzyme named as procerain, cleaves N-succinyl-Ala-Ala-Ala-p-nitroanilide but not -Ala-Ala-p-nitroanilide, -Ala p-nitroanilide and N-d-Benzoyl--Arg-p-nitroanilide and appears to be peptide length dependent. The extinction coefficient (epsilon 1% 280 nm) of the enzyme was 24.9 and it had no detectable carbohydrate moiety. Procerain contains eight tryptophan, 20 tyrosine and seven cysteine residues forming three disulfide bridges, and the remaining one being free. Procerain retains full activity over a broad range of pH 3.0-12.0 and temperatures up to 70 degree C, besides being stable at very high concentrations of chemical denaturants and organic solvents. Polyclonal antibodies against procerain do not cross-react with other related proteases. Procerain unlike most of the plant cysteine proteases has blocked N-terminal residue.

Hieronymain I, a new cysteine peptidase isolated from unripe fruits of Bromelia hieronymi Mez (Bromeliaceae)

A new peptidase, named hieronymain I, was purified to homogeneity from unripe fruits of Bromelia hieronymi Mez (Bromeliaceae) by acetone fractionation followed by cation exchange chromatography (FPLC) on CM-Sepharose FF. Homogeneity of the enzyme was confirmed by mass spectroscopy (MALDI-TOF), isoelectric focusing, and SDS-PAGE. Hieronymain is a basic peptidase (pI > 9.3) and its molecular mass was 24,066 Da. Maximum proteolytic activity on casein (>90% of maximum activity) was achieved at pH 8.5-9.5. The enzyme was completely inhibited by E-64 and iodoacetic acid and activated by the addition of cysteine; these results strongly suggest that the isolated protease should be included within the cysteine group. The N-terminal sequence of hieronymain (ALPESIDWRAKGAVTEVKRQDG) was compared with 25 plant cysteine proteases that showed more than 50% of identity.

Purification and characterization of macrodontain I, a cysteine peptidase from unripe fruits of Pseudananas macrodontes (Morr.) harms (Bromeliaceae)

A new papain-like cysteine peptidase isolated from fruits of Pseudananas macrodontes (Morr.) Harms, a species closely related to pineapple (Ananas comosus L.), has been purified and characterized. The enzyme, named macrodontain I, is the main proteolytic component present in fruit extracts and was purified by acetone fractionation followed by anion-exchange chromatography. Separation was improved by selecting both an adequate pH value and a narrow saline gradient. Optimum pH range (more than 90% of maximum activity with casein) was achieved at pH 6.1-8.5. Homogeneity of the enzyme was confirmed by bidimensional electrophoresis and mass spectroscopy (MS). Molecular mass of the enzyme was 23,459 (MS) and its isoelectric point was 6.1. The alanine, glutamine, and tyrosine derivatives were strongly preferred when the enzyme was assayed on N-alpha-CBZ-l-amino acid p-nitrophenyl esters. The N-terminal sequence of macrodontain (by comparison with the N-terminus of 30 plant proteases with more than 50% homology) showed a great deal of sequence similarity to the other pineapple-stem-derived cysteine endopeptidases, being 85.7, 85. 2, and 77.8% identical to comosain, stem bromelain, and ananain, respectively. It seems clear that the Bromeliaceae endopeptidases are more closely related to each other than to other members of the papain family, suggesting relatively recent divergence.

Enzymatic hydrolysis of copoly(N-hydroxypropyl-L-glutamine/L-leucine) hydrogels in vitro

Two component random copolypeptide hydrogels consisting of N-hydroxyalkyl L-glutamine and L-leucine were prepared by carrying out aminolysis reactions with 3-amino-1-propanol(P) together with cross-linking reactors with 1,8-octamethylenediamine (OMDA) on hydrogels of the starting copolymers consisting of gamma-methyl-L-glutamate(M) and L-leucine(L). The relation between their bulk structure and properties was investigated with regard to the swelling ration in water, aqueous vapor permeability, tensile properties, and enzymatic degradation behavior in a pseudoextracellular fluid (PECF). The tensile property of the hydrogels was highly dependent on the swelling ratio in PECF, and on the hydrophobicity of the side chains, whose behavior was typical of an elastomer. It was shown that a common relation was obtained between the rate of water vapor permeabilities and the swelling ratio of hydrogels in PECF regardless of the difference of the nature of side chains. Biodegradation of the hydrogels in vitro by bromelain indicated that the degradation took place in bulk rather than on surface, and that the rate of degradation was also highly dependent on the swelling ratio of samples as well as on the hydrophobicity of the side chains of samples.

Biodegradation of random copolypeptide membranes consisting of N-hydroxyalkyl L-glutamine as one component

Two component random copolypeptide membranes, consisting of N-hydroxyalkyl L-glutamine and L-alanine or L-leucine were prepared by carrying out aminolysis reactions with 2-amino-1-ethanol (E) or 5-amino-1-pentanol (Pe), together with a cross-linking reaction with 1,8-octamethylenediamine (OMDA) on membranes of the starting copolymers consisting of gamma-benzyl L-glutamate (B) and L-alanine (A) or L-leucine (L). The relationships between their bulk structure and membrane properties were investigated, such as the swelling ratio in water, aqueous vapour permeability, tensile properties and enzymatic degradation behaviour of the membranes in a pseudo-extracellular fluid (PECF). The tensile properties of the hydrophilic membranes were highly dependent on the swelling ratio of PECF, and the hydrophobicity of the side chains, whose behaviour was typical of an elastomer. We showed that a common relation was obtained between the rate of water vapour permeability and the swelling ratio of membranes in PECF despite the difference of the nature of the side chains. Biodegradation of these membranes in vitro by bromelain indicated that the degradation was a bulk rather than a surface phenomenon, and that the rate of degradation was also highly dependent on the swelling ratio of samples and on the hydrophobicity of the side chains of samples.

Evidence that the gluconeogenic pathway is confined to an enriched Müller cell fraction derived from the amphibian retina

An enriched Müller cell fraction was prepared from bullfrog retina, employing the endoprotease bromelain to digest the retina, and iso-osmotic Percoll gradient centrifugation to resolve the retinal digest. The Müller cell was the most resistant of all retinal cells to bromelain digestion, thus large numbers of morphologically intact cells were produced. The only other retinal cells that survived bromelain digestion were cones and some bipolar cells. The enriched Müller cells were incubated in 10 mm lactate Ringer containing U-[14C]lactate and the amount of [14C]glucose synthesized was used as the biochemical endpoint for assessing the rate of gluconeogenesis. There was no incorporation of [14C]glucose into Müller cell glycogen: however, 2.8 nmol glucose (mg Müller cell protein x hr)-1 was released to the medium. The synthesis and release of glucose to the medium was increased four- to sixfold by glucagon, vasoactive intestinal peptide or a mixture of forskolin/IBMX. In addition, glycolytic flux of isolated intact retina was determined with 3-[3H]glucose. In lactate-free and lactate-containing Ringer, glycolytic flux was 92.5 and 67.9 nmol (mg protein x hr)-1, respectively. In the presence of 100 nM vasoactive intestinal peptide, glycolytic flux in lactate-free and lactate-containing Ringer was reduced by 50 and 66%, respectively. These data strongly suggest that a Cori-like cycle exists in the amphibian retina and the Müller cell may be the predominant site for the gluconeogenic pathway. In addition, vasoactive intestinal peptide may serve both as a gluconeogenic and antiglycolytic neurohormone in the amphibian retina.

The relationship between the chromophore moiety and the cation binding sites in bacteriorhodopsin

Bleaching of the purple membrane strongly reduces the number of divalent cation binding sites as well as their affinities. Conversely, deionization of the bleached membrane drastically inhibits the chromophore regeneration. Proteolysis experiments using bromelain show that the bleached membrane has an additional cleavage site probably located at the fifth loop, whereas in the blue membrane, the C-terminal tail is no longer susceptible to proteolysis. It is suggested that there exists a close relationship between the retinal environment and one or more of the cation binding sites.