Showing papers on "Proteolytic enzymes published in 2022"

Gut Microbial β-Glucuronidases Regulate Host Luminal Proteases and are depleted in Irritable Bowel Syndrome

Abstract: Intestinal proteases mediate digestion and immune signalling, while increased gut proteolytic activity disrupts the intestinal barrier and generates visceral hypersensitivity, which is common in irritable bowel syndrome (IBS). However, the mechanisms controlling protease function are unclear. Here we show that members of the gut microbiota suppress intestinal proteolytic activity through production of unconjugated bilirubin. This occurs via microbial β-glucuronidase-mediated conversion of bilirubin conjugates. Metagenomic analysis of faecal samples from patients with post-infection IBS (n = 52) revealed an altered gut microbiota composition, in particular a reduction in Alistipes taxa, and high gut proteolytic activity driven by specific host serine proteases compared with controls. Germ-free mice showed 10-fold higher proteolytic activity compared with conventional mice. Colonization with microbiota samples from high proteolytic activity IBS patients failed to suppress proteolytic activity in germ-free mice, but suppression of proteolytic activity was achieved with colonization using microbiota from healthy donors. High proteolytic activity mice had higher intestinal permeability, a higher relative abundance of Bacteroides and a reduction in Alistipes taxa compared with low proteolytic activity mice. High proteolytic activity IBS patients had lower fecal β-glucuronidase activity and end-products of bilirubin deconjugation. Mice treated with unconjugated bilirubin and β-glucuronidase-overexpressing E. coli significantly reduced proteolytic activity, while inhibitors of microbial β-glucuronidases increased proteolytic activity. Together, these data define a disease-relevant mechanism of host-microbial interaction that maintains protease homoeostasis in the gut.

d-Amino Acid-Based Antifouling Peptides for the Construction of Electrochemical Biosensors Capable of Assaying Proteins in Serum with Enhanced Stability.

Abstract: The susceptibility of peptides to proteolytic degradation in human serum significantly hindered the potential application of peptide-based antifouling biosensors for long-term assaying of clinical samples. Herein, a robust antifouling biosensor with enhanced stability was constructed based on peptides composed of d-amino acids (d-peptide) with prominent proteolytic resistance. The electrode was electropolymerized with poly(3,4-ehtylenedioxythiophene) and electrodeposited with Au nanoparticles (AuNPs), and the d-peptide was then immobilized onto the AuNPs, and a typical antibody specific for immunoglobulin M (IgM) was immobilized. Because of the effect of d-amino acids, the d-peptide-modified electrode surface showed prominent antifouling capability and high tolerance to enzymatic hydrolysis. Moreover, the d-peptide-modified electrode exhibited much stronger long-term stability, as well as antifouling ability in human serum than the electrode modified with normal peptides. The electrochemical biosensor exhibited a sensitive response to IgM linearly within the range of 100 pg mL-1 to 1.0 μg mL-1 and a very low detection limit down to 37 pg mL-1, and it was able to detect IgM in human serum with good accuracy. This work provided a new strategy to develop robust peptide-based biosensors to resist the proteolytic degradation for practical application in complex clinical samples.

Effects of Moderate Enzymatic Hydrolysis on Structure and Functional Properties of Pea Protein

Abstract: Pea protein (PP) was moderately hydrolyzed using four proteolytic enzymes including flavourzyme, neutrase, alcalase, and trypsin to investigate the influence of the degree of hydrolysis (DH) with 2%, 4%, 6%, and 8% on the structural and functional properties of PP. Enzymatic modification treatment distinctly boosted the solubility of PP. The solubility of PP treated by trypsin was increased from 10.23% to 58.14% at the 8% DH. The results of SDS-PAGE indicated the protease broke disulfide bonds, degraded protein into small molecular peptides, and transformed insoluble protein into soluble fractions with the increased DH. After enzymatic treatment, a bathochromic shift and increased intrinsic fluorescence were observed for PP. Furthermore, the total sulfhydryl group contents and surface hydrophobicity were reduced, suggesting that the unfolding of PP occurred. Meanwhile, the foaming and emulsification of PP were improved after enzymatic treatment, and the most remarkable effect was observed under 6% DH. Moreover, under the same DH, the influence on the structure and functional properties of PP from large to small are trypsin, alcalase, neutrase and flavourzyme. This result will facilitate the formulation and production of natural plant-protein-based products using PP.

Identification of Arginine Phosphorylation in Mycolicibacterium smegmatis

Abstract: Mycobacteria that cause tuberculosis infections employ proteolytic pathways that modulate cellular behavior by destroying specific proteins in a highly regulated manner. Some proteolytic enzymes have emerged as novel antibacterial targets against drug-resistant tuberculosis infections. ABSTRACT Tuberculosis is a leading cause of worldwide infectious mortality. The prevalence of multidrug-resistant Mycobacterium tuberculosis infections drives an urgent need to exploit new drug targets. One such target is the ATP-dependent protease ClpC1P1P2, which is strictly essential for viability. However, few proteolytic substrates of mycobacterial ClpC1P1P2 have been identified to date. Recent studies in Bacillus subtilis have shown that the orthologous ClpCP protease recognizes proteolytic substrates bearing posttranslational arginine phosphorylation. While several lines of evidence suggest that ClpC1P1P2 is similarly capable of recognizing phosphoarginine-bearing proteins, the existence of phosphoarginine modifications in mycobacteria has remained in question. Here, we confirm the presence of posttranslational phosphoarginine modifications in Mycolicibacterium smegmatis, a nonpathogenic surrogate of M. tuberculosis. Using a phosphopeptide enrichment workflow coupled with shotgun phosphoproteomics, we identified arginine phosphosites on several functionally diverse targets within the M. smegmatis proteome. Interestingly, phosphoarginine modifications are not upregulated by heat stress, suggesting divergent roles in mycobacteria and Bacillus. Our findings provide new evidence supporting the existence of phosphoarginine-mediated proteolysis by ClpC1P1P2 in mycobacteria and other actinobacterial species. IMPORTANCE Mycobacteria that cause tuberculosis infections employ proteolytic pathways that modulate cellular behavior by destroying specific proteins in a highly regulated manner. Some proteolytic enzymes have emerged as novel antibacterial targets against drug-resistant tuberculosis infections. However, we have only a limited understanding of how these enzymes function in the cell and how they select proteins for destruction. Some proteolytic enzymes are capable of recognizing proteins that carry an unusual chemical modification, arginine phosphorylation. Here, we confirm the existence of arginine phosphorylation in mycobacterial proteins. Our work expands our understanding of a promising drug target in an important global pathogen.

Does Microsecond Active-Site Dynamics Primarily control Proteolytic Activity of Bromelain? Clues from Single Molecular Level Study with a Denaturant, a Stabilizer and a Macromolecular Crowder.

Abstract: Proteins are dynamic entity with various molecular motions at different timescale and length scale. Molecular motions are crucial for the optimal function of an enzyme. It seems intuitive that these motions are crucial for optimal enzyme activity. However, it is not easy to directly correlate an enzyme's dynamics and activity due to biosystems' enormous complexity. amongst many factors, structure and dynamics are two prime aspects that combinedly control the activity. Therefore, having a direct correlation between protein dynamics and activity is not straightforward. Herein, we observed and correlated the structural, functional, and dynamical responses of an industrially crucial proteolytic enzyme, bromelain with three versatile classes of chemicals: GnHCl (protein denaturant), sucrose (protein stabilizer), and Ficoll-70 (macromolecular crowder). The only free cysteine (Cys-25 at the active-site) of bromelain has been tagged with a cysteine-specific dye to unveil the structural and dynamical changes through various spectroscopic studies both at bulk and at the single molecular level. Proteolytic activity is carried out using casein as the substrate. GnHCl and sucrose shows remarkable structure-dynamics-activity relationships. Interestingly, with Ficoll-70, structure and activity are not correlated. However, microsecond dynamics and activity are beautifully correlated in this case also. Overall, our result demonstrates that bromelain dynamics in the microsecond timescale around the active-site is probably a key factor in controlling its proteolytic activity.

A Disintegrin and Metalloproteinase (ADAM) Family—Novel Biomarkers of Selected Gastrointestinal (GI) Malignancies?

Abstract: Simple Summary A disintegrin and metalloproteinase (ADAM) proteins are proteolytic enzymes that are responsible for destroying the extracellular matrix, but they also have adhesive properties. Recent investigations have demonstrated that the expression of several ADAMs is upregulated in gastrointestinal (GI) tumour cells and have linked the secretion of these proteins to pathogenesis of GI malignancies. Therefore, the aim of this review is to establish the involvement of selected ADAMs in the progression of GI malignancies as well as their prognostic significance. It was found that selected ADAMs might stimulate the proliferation and invasion of malignant cells and may be associated with unfavourable survival of patients with GI tumours. In conclusion, this review confirms the significance of selected ADAMs in the pathogenesis of the most common GI cancers and indicates their promising significance as potential prognostic biomarkers as well as therapeutic targets for GI malignancies. Abstract The global burden of gastrointestinal (GI) cancers is expected to increase. Therefore, it is vital that novel biomarkers useful for the early diagnosis of these malignancies are established. A growing body of data has linked secretion of proteolytic enzymes, such as metalloproteinases (MMPs), which destroy the extracellular matrix, to pathogenesis of GI tumours. A disintegrin and metalloproteinase (ADAM) proteins belong to the MMP family but have been proven to be unique due to both proteolytic and adhesive properties. Recent investigations have demonstrated that the expression of several ADAMs is upregulated in GI cancer cells. Thus, the objective of this review is to present current findings concerning the role of ADAMs in the pathogenesis of GI cancers, particularly their involvement in the development and progression of colorectal, pancreatic and gastric cancer. Furthermore, the prognostic significance of selected ADAMs in patients with GI tumours is also presented. It has been proven that ADAM8, 9, 10, 12, 15, 17 and 28 might stimulate the proliferation and invasion of GI malignancies and may be associated with unfavourable survival. In conclusion, this review confirms the role of selected ADAMs in the pathogenesis of the most common GI cancers and indicates their promising significance as potential prognostic biomarkers as well as therapeutic targets for GI malignancies. However, due to their non-specific nature, future research on ADAM biology should be performed to elucidate new strategies for the diagnosis of these common and deadly malignancies and treatment of patients with these diseases.

Degradation of Hybrid Drug Delivery Carriers with a Mineral Core and a Protein–Tannin Shell under Proteolytic Hydrolases

Abstract: Hybrid carriers with the mineral CaCO3/Fe3O4 core and the protein–tannin shell are attractive for drug delivery applications due to reliable coupling of anticancer drugs with protein–tannin complex and the possibility of remote control over drug localization and delivery by the external magnetic field. This study aims to elucidate the mechanisms of drug release via enzymatic degradation of a protein–tannin carrier shell triggered by proteolytic hydrolases trypsin and pepsin under physiological conditions. To do this, the carriers were incubated with the enzyme solutions in special buffers to maintain the enzyme activity. The time-lapse spectrophotometric and electron microscopy measurements were carried out to evaluate the degradation of the carriers. It was established that the protein–tannin complex demonstrates the different degradation behavior depending on the enzyme type and buffer medium. The incubation in trypsin solution mostly resulted in the protein shell degradation. The incubation in pepsin solution did not affect the protein component; however, the citric buffer stimulates the degradation of the mineral core. The presented results allow for predicting the degradation pathways of the carriers including the release profile of the loaded cargo under physiological conditions. The viability of 4T1 breast cancer cells with mineral magnetic carriers with protein–tannin shells was investigated, and their movement in the fields of action of the permanent magnet was shown.

Combined Effects of Pressure Cooking and Enzyme Treatment to Enhance the Digestibility and Physicochemical Properties of Spreadable Liver Sausage

Abstract: Abstract This study aimed to determine the effect of enzyme, guar gum, and pressure processing on the digestibility and physicochemical properties of age-friendly liver sausages. Liver sausages were manufactured by adding proteolytic enzyme (Bromelain) and guar gum, and pressure-cooking (0.06 MPa), with the following treatments: control, without proteolytic enzyme; T1, proteolytic enzyme; T2, proteolytic enzyme and guar gum; T3, pressure-cooking; T4, proteolytic enzyme and pressure-cooking; T5, proteolytic enzyme, guar gum, and pressure-cooking. The pH was high in the enzyme- and pressure-processed groups. The pressure-processed groups had lower apparent viscosity than other cooking groups, and it decreased during enzyme treatment. Hardness was lower in the enzyme- and pressure-processed groups than in the control, and the T4 was the lowest. Digestibility was the highest in T4 at 82.58%, and there was no significant difference with that in T5. The general cooking group with enzyme and guar gum also showed higher digestibility than the control (77.50%). As a result of the sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the enzyme- and pressure-treated groups (T4, T5) were degraded more into low-molecular-weight peptides (≤37 kDa) than the control and other treatments. Viscoelasticity showed similar trends for viscous and elastic moduli. Similarly, combined pressure processing and enzymatic treatment decreased viscoelasticity, while guar gum increased elasticity but decreased viscosity. Therefore, the tenderized physical properties and improved digestibility by enzyme and pressurization treatment could be used to produce age-friendly spreadable liver sausages.

Codonopsis pilosula and fish collagen yogurt: Proteolytic, potential Angiotensin-I converting enzyme (ACE) inhibitory activity and sensory properties

Abstract: The effects of Codonopsis pilosula (CP) and/or fish collagen (FC) on post-acidification, proteolysis of milk proteins, angiotensin-I converting enzyme (ACE) inhibitory activity, and sensory evaluation were investigated in yogurt during 0, 7, & 21 days of storage at 4 °C. Two groups of yogurt samples were prepared: group 1 included plain yogurt (control) and CP-yogurt; group 2 included plain yogurt + FC (control) and CP-yogurt + FC. CP- yogurt showed a significant increase in total titratable acidity (TTA) on day 7 of storage. The presence of FC in yogurt significantly improved (p < 0.05) the content of free amino acids (FAA) compared to the absence. O -phthaldialdehyde (OPA) peptide concentration increased (p < 0.05) to the highest amount for CP-yogurt ± FC on day 7 of storage. In addition, more degradation was observed in bovine serum albumin (BSA), α-, β-, & κ-caseins, β-lactoglobulin, and α -lactalbumin of CP - yogurt + FC than its control on day 7 of storage. CP- yogurt with/without FC showed higher (p < 0.05) inhibitory ACE activity than their respective controls on day 7 of storage. The addition of fish collagen in CP- yogurt seemed to have good scoring in sensory evaluation. In conclusion, the presence of C. pilosula and fish collagen in the yogurt can bring about promising health benefits such as anti-ACE activity. • FC in yogurt improved the content of FAA. • CP-yogurt ± FC showed the highest OPA peptide on day 7 of storage. • CP - yogurt + FC showed more degradation of milk proteins on day 7 of storage. • CP- yogurt ± FC showed the highest ACE inhibitory activity on day 7 of storage. • CP- yogurt + FC has a good influence on the overall taste score on 0 & 7 days of storage.

Lactic Acid Bacteria: Proteolytic Systems

Abstract: Only a part of the proteolytic system of lactic acid bacteria (LAB), a cell-wall protease and a set of intracellular peptidases essential for optimal growth in milk, has been extensively explored. However, analysis of LAB genomes revealed the presence of up to 40 putative proteolytic enzymes per species, the role of half remaining unknown. Recent data indicate that proteolysis at LAB surface is more intense than expected so far. The role of the proteolytic system of LAB in regulation, protein maturation, secretion or degradation remains to be understood to better control these industrially-relevant bacteria.

Bacteria of the Black Sea Are Producers of Proteolytic Enzymes

Abstract: Despite the fact that in recent years there has been a certain enhancing interest in the study of marine microorganisms, nevertheless, marine bacteria as producers of biologically active substances, in particular enzymes, are still poorly studied. The marine biota is significantly different from the terrestrial one; therefore, there is a high probability of detecting in the marine environment different from terrestrial bacteria producers of enzymes with unique specificity and activity, for the needs of modern biotechnology. Proteolytic enzymes play an important role in these studies. Since the majority of microbial producers are characterized by a number of serious deficiencies, in particular, most of the elastase producers described in the literature are pathogenic for humans, the search for new, effective producers continues to be an urgent problem, given that highly active producers of proteolytic enzymes, in particular elastase, are generally absent in Ukraine. In this regard, the purpose of this work was to screen microorganisms isolated from the Black Sea for the presence of effective producers of proteolytic enzymes. Methods. We used methods of determining proteolytic (caseinilytic, elastolytic, fibrinolytic, fibrinogenolytic) activity. Results. The study of the enzymatic activity of the isolates showed that on the 10th day of cultivation in the supernatant of the culture liquid, caseinolytic activity was not detected only in one isolate 56, whereas very insignificant activity was observed in isolates 7, 20, and 50. The maximum activity was detected in isolate 247 (0.2 units/mL), and lower one - in isolates 46 (0.16 U/mL), 52 (0.15 U/mL), 51 (0.135 U/mL), 54 (0.08 U/mL), and 44 (0.05 U/mL). Of the 10 studied isolates, elastase activity was found only in four of them. The highest activity was found in isolates 51 and 54 (20.83 and 19.96 U/mL, respectively). Lower levels of activity (15.62 U/mL and 12.15 U/mL, respectively) were shown by isolates 52 and 247. The studied isolates also differed in their ability to hydrolyze fibrin and fibrinogen. T e highest fi brinolytic activity (2.33 U/mL) was found in isolates 46 and 54, significantly lower in isolate 20 (0.5 U/mL) and isolate 44 (0.33 U/mL). The rest isolates did not show fibrinolytic activity. As for fibrinogenolytic activity, it was noted in 6 studied cultures. The highest levels of activity were observed in isolate 51 (1.16 U/mL). Lower activity was found in isolates 54 (0.66 U/mL), 7 (0.5 U/mL), and 247 (0.33 U/mL). In isolate 50, it was minimal (0.083 U/mL). Conclusions. No correlation was found between elastase, fibrinolytic and fibrinogenic activity in the studied isolates. Thus, isolates 51, 54 and, to a lesser extent, 52 and 247 synthesize elastase activity. The highest fibrinolytic activity was in isolates 46 and 54, and fibrinogenolytic activity was in isolate 51. It was shown that the Black Sea is rich in marine bacterial species, which can be effective producers of a number of practically important enzymes, in particular, proteolytic ones with specificity to elastin, fibrin, and fibrinogen, which can be promising for implementation in biotechnological processes.

Development of Enzyme-Based Cosmeceuticals: Studies on the Proteolytic Activity of Arthrospira platensis and Its Efficient Incorporation in a Hydrogel Formulation

Abstract: Microalgae are a valuable source of enzymes and active ingredients due to their biochemical variability, health-beneficial properties, lower production cost and viability on an industrial scale. In addition, the growing demand for sustainable products constitutes microalgae as a viable resource for the development of a range of innovative products. In the present work, the proteolytic activity of Arthrospira platensis lysate was assessed and characterized using kinetics analysis and zymography employing different substrates, pH values and divalent ions. The results suggest the presence of two main proteolytic enzymes in the lysate. In addition, a rapid and easy purification protocol of the proteolytic activity, under mild conditions, was developed using a polyethyleneglycol (PEG)/phosphate aqueous two-phase system (ATPS). The proteolytic activity of A. platensis lysate was used to develop a hydrogel formulation as an enzyme-based cosmeceutical, with potential application as a topical exfoliating agent. The incorporation of the A. platensis extract in the developed hydrogel formulation significantly improved its operational stability over time, which is a significant advantage in enzyme-based product development.

Message in the bottle: regulation of the tumor microenvironment via exosome-driven proteolysis

Abstract: Exosomes comprise a subtype of extracellular vesicles involved in cell-to-cell communication, specifically by transporting biological molecules, such as proteins and nucleic acids, to either local or more distant recipient cells, thus triggering distinct biological behaviors. Included in the exosome cargo is frequently a wide range of proteolytic enzymes, such as the matrix metalloproteinases (MMPs), the disintegrin and metalloproteinases (ADAMs), and the ADAM with thrombospondin-like motifs (ADAMTSs), whose functions contribute to the development and progression of cancer. In recent years, extensive research on the potential use of exosomes in diagnostic and therapeutic applications for personalized medicine has emerged, but the targeting of the proteolytic cargo of exosomes has not been fully exploited in this direction. In this review, we aim to explore both the mechanistic and the translational importance of proteolytic enzymes carried by the tumor cell–derived exosomes, as well as their role in the acquisition and support of certain hallmarks of cancer.

The Role of Proteolysis in Amyloidosis

Abstract: Amyloidoses are a group of diseases associated with deposits of amyloid fibrils in different tissues. So far, 36 different types of amyloidosis are known, each due to the misfolding and accumulation of a specific protein. Amyloid deposits can be found in several organs, including the heart, brain, kidneys, and spleen, and can affect single or multiple organs. Generally, amyloid-forming proteins become prone to aggregate due to genetic mutations, acquired environmental factors, excessive concentration, or post-translational modifications. Interestingly, amyloid aggregates are often composed of proteolytic fragments, derived from the degradation of precursor proteins by yet unidentified proteases, which display higher amyloidogenic tendency compared to precursor proteins, thus representing an important mechanism in the onset of amyloid-based diseases. In the present review, we summarize the current knowledge on the proteolytic susceptibility of three of the main human amyloidogenic proteins, i.e., transthyretin, β-amyloid precursor protein, and α-synuclein, in the onset of amyloidosis. We also highlight the role that proteolytic enzymes can play in the crosstalk between intestinal inflammation and amyloid-based diseases.

ADAM17 Mediates Proteolytic Maturation of Voltage-Gated Calcium Channel Auxiliary α2δ Subunits, and Enables Calcium Current Enhancement

Abstract: Abstract The auxiliary α2δ subunits of voltage-gated calcium (CaV) channels are key to augmenting expression and function of CaV1 and CaV2 channels, and are also important drug targets in several therapeutic areas, including neuropathic pain. The α2δ proteins are translated as preproteins encoding both α2 and δ, and post-translationally proteolyzed into α2 and δ subunits, which remain associated as a complex. In this study, we have identified ADAM17 as a key protease involved in proteolytic processing of pro-α2δ-1 and α2δ-3 subunits. We provide three lines of evidence: First, proteolytic cleavage is inhibited by chemical inhibitors of particular metalloproteases, including ADAM17. Second, proteolytic cleavage of both α2δ-1 and α2δ-3 is markedly reduced in cell lines by knockout of ADAM17 but not ADAM10. Third, proteolytic cleavage is reduced by the N-terminal active domain of TIMP-3 (N-TIMP-3), which selectively inhibits ADAM17. We have found previously that proteolytic cleavage into mature α2δ is essential for the enhancement of CaV function, and in agreement, knockout of ADAM17 inhibited the ability of α2δ-1 to enhance both CaV2.2 and CaV1.2 calcium currents. Finally, our data also indicate that the main site of proteolytic cleavage of α2δ-1 is the Golgi apparatus, although cleavage may also occur at the plasma membrane. Thus, our study identifies ADAM17 as a key protease required for proteolytic maturation of α2δ-1 and α2δ-3, and thus a potential drug target in neuropathic pain.

Lignin-Based Nanoparticles as Both Structural and Active Elements in Self-Assembling and Self-Healing Multifunctional Hydrogels for Chronic Wound Management

Abstract: Efficient wound healing is feasible when the dressing materials simultaneously target multiple factors causing wound chronicity, such as deleterious proteolytic and oxidative enzymes and bacterial infection. Herein, entirely bio-based multifunctional self-assembled hydrogels for wound healing were developed by simply mixing two biopolymers, thiolated hyaluronic acid (HA-SH) and silk fibroin (SF), with lignin-based nanoparticles (NPs) as both structural and functional elements. Sono-enzymatic lignin modification with natural phenolic compounds results in antibacterial and antioxidant phenolated lignin nanoparticles (PLN) capable of establishing multiple interactions with both polymers. These strong and dynamic polymer-NP interactions endow the hydrogels with self-healing and shear-thinning properties, and pH-responsive NP release is triggered at neutral to alkaline pH (7–9). Despite being a physically crosslinked hydrogel, the material was stable for at least 7 days, and its mechanical and functional properties can be tuned depending on the polymer and NP concentration. Furthermore, human skin cells in contact with the nanocomposite hydrogels for 7 days showed more than 93% viability, while the viability of clinically relevant Staphylococcus aureus and Pseudomonas aeruginosa was reduced by 99.7 and 99.0%, respectively. The hydrogels inhibited up to 52% of the activity of myeloperoxidase and matrix metalloproteinases, responsible for wound chronicity, and showed a strong antioxidant effect, which are crucial features promoting wound healing.

Plant proteases, their properties and therapeutic use

Abstract: Plant enzymes have a wide range of therapeutic activity and are characterized by minor side effects. Especially important are proteases that are actively used in medicine. They accumulate in a plant’s latex and are characterized by stability and high proteolytic activity. Among them, the most widely studied are the enzyme papain, which is obtained from the fruit of the unripe Papaya plant (Carica papaya) and bromelain from the stem and fruit of pineapple (Ananas comosus). There are different ways of isolating and purifying these enzymes, as well as various methods of chemical modification for their quality improvement. The present review article describes the characterization of plant proteases, various methods of their obtaining and modification, their therapeutic significance and the existing literature on the given topic.

Calpain-mediated proteolysis as driver and modulator of polyglutamine toxicity

Abstract: Among posttranslational modifications, directed proteolytic processes have the strongest impact on protein integrity. They are executed by a variety of cellular machineries and lead to a wide range of molecular consequences. Compared to other forms of proteolytic enzymes, the class of calcium-activated calpains is considered as modulator proteases due to their limited proteolytic activity, which changes the structure and function of their target substrates. In the context of neurodegeneration and - in particular - polyglutamine disorders, proteolytic events have been linked to modulatory effects on the molecular pathogenesis by generating harmful breakdown products of disease proteins. These findings led to the formulation of the toxic fragment hypothesis, and calpains appeared to be one of the key players and auspicious therapeutic targets in Huntington disease and Machado Joseph disease. This review provides a current survey of the role of calpains in proteolytic processes found in polyglutamine disorders. Together with insights into general concepts behind toxic fragments and findings in polyglutamine disorders, this work aims to inspire researchers to broaden and deepen the knowledge in this field, which will help to evaluate calpain-mediated proteolysis as a unifying and therapeutically targetable posttranslational mechanism in neurodegeneration.