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Prussian blue nanozymes were surface engineered with papain enzyme to develop processable nanoparticle dispersions with anti- oxidant and hydrolytic activities for biocatalytic applications. Enzyme coating improved the colloidal stability of the nanozymes and the obtained papain-Prussian blue hybrid showed remarkable peroxidase (vmax = 8.82 x 10-9 M s-1, KM = 12.3 mM), superoxide dismutase (IC50 = 14.6 ppm) and protease-like (41.2 U L-1) activities. [ABSTRACT FROM AUTHOR]

Papain is widely used in food, drug, and bioactive peptide production and must be immobilized onto carriers with biocompatibility. Dialdehyde starch (DAS) can be a good biocompatible cross‐linker according to its active aldehyde groups. In the present study, the magnetic nanoparticles dialdehyde starch (MDASN), synthesized by DAS and Fe3O4 magnetic nanoparticles (Fe‐MNP), are successfully used to immobilize papain to improve the enzymic activity. The structure and morphology of DAS, MDASN, and immobilized papain onto magnetic dialdehyde starch nanoparticles (papain‐MDASN) are characterized detailly. The morphology of DAS is like a flat ball, and that of Fe‐MNP and papain‐MDASN are spherical and clumpy. The particle size of Fe‐MNP and papain‐MDASN are small, resulting in a large surface electrostatic effect and partial agglomeration. Enzymic activity studies of papain‐MDASN exhibit that the immobilized papain on MDASN represents better temperature resistance, alkaline resistance, thermal stability, and reusability, and its activity recovery is up to 68.21%. Papain onto magnetic dialdehyde starch nanoparticles (MDASN) may enhance its potential application in production processes. [ABSTRACT FROM AUTHOR]

In this investigation, a nano-support containing cellulose nanocrystals – polydopamine (CP) was functionalized with glutaraldehyde (G) and utilized to immobilize papain. The properties of the supports and stabilized enzyme were characterized by TEM, SEM, DLS, Zeta-potential, FTIR, and EDS analyses. The optimal temperature of both papain forms was 60 °C, while the optimal pH value of the stabilized papain shifted from 7 to 8 after immobilization. The immobilized enzyme preparations showed higher stability at 80 and 90 °C and under acidic and alkaline conditions compared to the free enzyme. CPG-papain stability was higher than that of CP-papain. The K m values for free and immobilized papain on CP and CPG were 3.92, 3, and 2.74 mM respectively. K cat values were 9.05, 15.18, and 11.59 min−1 and catalytic efficiency values were 2.3, 5.05, and 4.23 mM−1.min−1. Additionally, the potential advantages of using a silver nanohydrid support were assessed. Although silver nanoparticles conveyed some catalytic activity to the final biocatalysts, they also caused a decrease in stability and activity of the immobilized papain. Therefore, the non-hybrid supports CP and CPG were more suitable candidates for the immobilization of papain than the hybrid supports. [Display omitted] • Cellulose nanocrystals – polydopamine support was synthesized. • Papain was covalently immobilized onto CP using glutaraldehyde. • Immobilizing the enzyme significantly enhanced its storage, thermal, and pH stability. • The K m kinetic parameter decreased while K cat /K m ratio increased. • The addition of AgNPs on the CP-papain worsened enzyme features [ABSTRACT FROM AUTHOR]

In this study, enzymatic [papain (P), bromelain (B), and A. oryzae-derived fungal protease (FP); enzyme ratios: 0.012 (v/v), 38 °C, 50 min] and non-enzymatic [control (C; saline), mineral water (95%)–lemon juice (5%) (ML) (1/2:w/v), 38 °C, 50 min)] tenderizing methods on European squid mantle (Loligo vulgaris Lamarck, 1798) were investigated. Scanning electron microscope (SEM) imaging, water holding capacity (WHC), cooking loss (CL), total free amino acids (TFAA), total soluble protein (TSP), hydroxyproline (Hyp), and Fourier-transform infrared spectroscopy (FTIR) analyses were performed on uncooked samples. pH, water activity (aw), color, nutritional changes, amino acids (AA), total volatile basic-nitrogen (TVB-N), Warner-Bratzler shear (WBS), texture profile analysis (TPA), and sensory evaluations were performed on both uncooked and cooked samples. A significant decrease in protein content was observed in group P (12.86%) compared to untreated (U) squid (15.16%). During frying, group P absorbed more cooking oil (8.37%) than the other groups. A higher degree of hydrolysis was observed in the enzymatically tenderized groups than in non-enzymatic groups, and a shift in secondary protein structures in favor of random coils. Hydrolysis was confirmed by Hyp and AA analyses. The total AA content order was found as B < P < FP < C < ML < U. ML and FP groups have relatively higher total bitter and umami AA compositions, especially in uncooked samples. FP and ML groups had more favorable results across all analyses, especially in terms of the sensory results, nutritional values, and TPA results of cooked samples. It is concluded that both methods are very convenient regarding industrial usage. [ABSTRACT FROM AUTHOR]

In this study, the effect of protease hydrolysis on the stability and flavor of a sesame oil–paste system was investigated. The optimum amount of protease addition, determined by testing the effects of protease addition on the improvement in the oil–paste separation of sesame paste (SP), was investigated using 7% neutral protease (NP), 5% papain (PP), 7% trypsin (TP), and 5% flavourzyme (FZ). The flavor differences among these four groups of samples were investigated, and storage experiments were conducted for 28 days to observe the changes in quality. Finally, the principal component analysis (PCA) calculations showed that the samples in the 5% FP group performed the best, with a considerable improvement in the stability of the sesame paste–oil system during storage. The oil separation capacity (OSC) decreased by 9.1% during storage, the acid value (AV) increased by 1.00 mg/g and the peroxide value (POV) increased by 0.3 mmol/kg compared with those of the control group. This group also had the highest total sensory (4.25 score) and nutty (5.83 score) scores based on the total pyrazine content. Therefore, protease hydrolysis has promising application prospects for increasing the stability of sesame paste. [ABSTRACT FROM AUTHOR]

Plant-based foods offer a sustainable alternative to meet the growing protein demand. Legumes are the most promising of these, as they contain relatively high concentrations of protein, low digestible starch, and dietary fiber, as well as them possibly featuring low levels of fat. Enzymatically modified legume proteins provide us with tempting perspectives in terms of enhancing foods' biological values. However, their bioavailability and digestibility are generally less sufficient than that of proteins of animal origin, which may be improved by well-tailored enzyme modification. In this study, the efficacy of three plant-based proteases (bromelain, ficin, and papain) were evaluated at two distinct concentrations (2.5% and 10%) and three hydrolysis durations (1, 2, and 12 h) when transforming chickpea and lentil proteins. The degree of hydrolysis (DH), peptide profiles, and free amino acid content were analyzed to determine the efficiency of each enzyme. Results showed significant variations in DH, which was influenced by enzyme type, concentration, and hydrolysis duration. Papain exhibited the highest DH, particularly at a 10% concentration, reaching 27.8% efficiency in chickpea and 34.8% in lentils after 12 h. Bromelain and ficin were proven to be less effective, with ficin showing the least hydrolytic activity. SDS-PAGE analysis revealed substantial protein degradation, especially subsequent to papain treatment, pointing out that most proteins were cleaved into smaller peptides. SEC-HPLC indicated a predominant release of peptides within the 200–1000 Da range, suggesting enhanced bioavailability. Papain and bromelain treatments resulted in a significant release of oligopeptides and dipeptides. UHPLC analysis highlighted a marked post-hydrolysis increase in total free amino acids, with arginine, leucine, and lysine being the most abundant ones. Notably, tryptophan, being undetectable in untreated samples, was released in measurable amounts post-hydrolysis. These findings demonstrate papain's superior performance in protein hydrolysis and its potential in producing bioactive peptides, highlighting its applicability in food processing and the development of both nutraceuticals and functional foods. [ABSTRACT FROM AUTHOR]

Epimedium is used in traditional Chinese medicine. Epimedium polysaccharides have a variety of physiological properties. This study compared three different processes for the extraction of polysaccharides from Epimedium spp., including ultrasonic, aqueous enzymatic, and microwave extraction, to optimize the extraction conditions and determine the optimal extraction method. The optimal parameters for each method were analyzed. The results showed that the optimal process for ultrasonic extraction was an ultrasonic power of 250 W, an extraction time of 60 min, a temperature of 50 °C, and a solid–liquid ratio of 1:35. The optimal conditions for the aqueous enzymatic method were a papain concentration of 70 U/mL, extraction time of 70 min, a temperature of 50 °C, and a material-to-liquid ratio of 1:30, while those for microwave extraction were a microwave power of 650 W, an extraction time of 50 min, a temperature of 40 °C, and a material-to-liquid ratio of 1:25. The polysaccharide yields were 4.85%, 4.72%, and 3.98% for the three methods, respectively, indicating that ultrasonic extraction resulted in the highest yield of polysaccharides from Epimedium brevicornum. After purification with DEAE-cellulose, the polysaccharide yields were 4.13%, 3.67%, and 3.12%, respectively. A comprehensive comparison demonstrated the superiority of the ultrasonic extraction method in terms of both extraction yield and purification efficiency. Characterization of the extracted Epimedium polysaccharides showed the presence of five monosaccharides, i.e., glucose, galactose, mannose, galacturonic acid, and rhamnose, and a number average molecular weight Mn of 1.65 × 105 Da and weight average molecular weight Mw of 6.61 × 105 Da. These results provide a scientific basis for the in-depth study and application of Epimedium polysaccharides. [ABSTRACT FROM AUTHOR]

The effect of a wide range of γ-radiation dose from 250 to 3000 kGy on the acute toxicity of papain administered to laboratory animals has been studied. It has been discovered that preliminary γ-irradiation of papain up to 1000 kGy reduces by more than five times the toxicity of its aqueous dispersions in the case of intraperitoneal administration. A further increase in the radiation dose to 3000 kGy does not lead to a noticeable change in the toxic effect. The study results indicate that γ-irradiation of papain may be used to reduce its toxicity. [ABSTRACT FROM AUTHOR]

In papain macromolecules irradiated with γ-rays, fragments with terminal primary amino groups were formed, and they appeared in the Fourier transform IR spectra as a broad peak with a maximum at 3440 cm–1 and an intense absorption band centered at 1706 cm–1 due to stretching vibrations of carbonyl groups. The intensity of the absorption bands of radiolysis products increased linearly with the irradiation dose of papain. Along with this, a noticeable weakening of the intensity of the absorption peaks of the peptide bond with radiation dose was observed to indicate radiation-induced degradation of the main chain of papain. [ABSTRACT FROM AUTHOR]

Objective: Preparation of protein–polysaccharide complexes allows to modulate practically significant characteristics of both components, thereby increasing not only the practical potential of the resulting structures, but also contributing to our understanding of the features of their interactions. Thus, the aim of this work was to study the structural and functional features of the complexes of cysteine proteases (bromelain, papain and ficin) with a graft copolymer of chitosan with poly(N,N-dimethylaminoethyl methacrylate) (CTS–DMAEMA), and also assess the effect of complexation processes on the protease activity and stability of the enzymes in question. Methods: The CTS–DMAEMA graft copolymer was obtained by solution radical polymerization in 2% acetic acid. Protein–polysaccharide complexes were received in glycine buffer. The protein content in the obtained complexes was determined by the modified Lowry method and proteolytic activity of enzymes as part of complexes was assessed using azocasein as a substrate. Molecular docking was used to identify the types of bonds and interactions within protein–polysaccharide complexes. Results and Discussion: Complexes of cysteine proteases (bromelain, papain, and ficin) with the graft copolymer of chitosan with poly(N,N-dimethylaminoethyl methacrylate) were synthesized. It was found that the complexes have a lower protease activity than the native enzymes, because as a result of complex formation, the active site of cysteine proteases is shielded from the substrate, which complicates the catalysis process. The complexes are more stable compared to the native enzymes and retain up to 26% of protease activity after 21 days of incubation at 37°C in Tris-HCl buffer (pH 7.5). Conclusions: It was found that the proteolytic activity of the complexes is lower compared to their native forms of enzymes. The results of molecular docking showed that the modified chitosan is located in the catalytic pocket of cysteine proteases globules. The synthesized complexes have increased stability on storage under physiological conditions, which makes them promising candidates for the development of wound healing drugs. [ABSTRACT FROM AUTHOR]

BACKGROUND RESULTS CONCLUSION This study explores enzymatic hydrolysis as a method of modifying soybean meal (SM). It can reduce the particle size, improve flavor, and convert macromolecules into absorbable nutrients. The purpose is to provide technical information regarding the use of SM. Papain alone, and a combination of papain and acid protease, and a mixture of papain, acid protease, and Lactiplantibacillus plantarum were employed for the enzymatic hydrolysis of SM.Sensory evaluation and nutritional and flavor analyses were performed with yogurt produced after SM enzymatic hydrolysis. The enzymatic hydrolysis improved yogurt quality significantly in comparison with non‐enzymatically hydrolyzed soybean meal yogurt (SMY) by accelerating the decrease in pH and shortening the duration of fermentation. Enzymatic hydrolysis also reduced beany flavors and bitterness and enhanced the aromatic compound, flavor‐related amino acid, and organic acid content, rendering the yogurt more appealing to consumers. Microstructural analysis revealed favorable characteristics that textural and rheological properties of the yogurt produced after enzymatically hydrolyzed SM were improved.In this study, the biotechnological approach was used to demonstrate the efficacy of enzymatic hydrolysis in improving the quality and value of SM, promoting the efficient application of SM in the food industry. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The present study focused on preparing rohu egg sauce using optimized conditions through enzymatic and fermentative methods. The enzymatic preparation of rohu egg sauce (ERS) involved homogenizing the eggs in water at a ratio of 1:0.9 (w/v), followed by the addition of salt (20% w/w) and papain (3% w/w). A mixture containing salt (25% w/w), sugar (7.5% w/w), and inoculum (10% (w/v)) of Pediococcus pentosaceus FSBP4-40 was utilized to prepare fermentatively produced rohu egg sauce (FRS). ERS and FRS were then stored at room temperature (25 ± 2 °C) and 37 °C for 180 days. After storage, both sauces were evaluated for their scavenging activity against DPPH, ABTS, and superoxide anion (SOA). The ERS demonstrated significantly higher DPPH, ABTS, and SOA scavenging activity compared to the FRS, with values of 61.61 ± 7.33%, 71.21 ± 2.14%, and 85.11 ± 4.92%, respectively, as opposed to 37.49 ± 5.34, 52.31 ± 1.76%, and 63.09 ± 2.31%. Significant changes were observed in the fatty acid profile of the sauces during 180 day storage. Furthermore, after 180 days, the bacterial counts in the FRS were much lower than in the ERS. Overall, this study highlights the importance of using enzymes and LAB in accelerating the hydrolytic process to produce biofunctional rohu egg sauce. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of ultrasound using papain and sodium bicarbonate (SC) on meat tenderness to achieve the desired texture for elderly individuals. Meats were immersed in distilled water (DW) or papain (PI), ultrasonically treated with papain (UPI), or ultrasonically treated with papain and SC (UPIS). Response surface methodology was used to optimize the processing conditions with the lowest hardness, and the optimal conditions were determined as follows: 400 U/mL papain, ultrasonic for 30 min, and 4% SC. Hardness, color, and myofibrillar fragmentation index (MFI) were investigated. The hardness followed the order of DW (22.50 N), PI (18.62 N), UPI (12.08 N), and UPIS (7.16 N), and UPIS showed the highest MFI. Papain and SC affected the color of the meat. Overall, ultrasound-assisted treatment using papain and SC resulted in hardness levels of less than 7.8 N, which can be easily compressed by low tongue pressure. [ABSTRACT FROM AUTHOR]

Background Results Conclusion Soybean meal yogurt was prepared from soybean meal using papain and Bifidobacterium animalis subsp. lactis. A non‐targeted metabolomics approach was employed to analyze the relevance of papain to the differences in volatile and non‐volatile metabolites of soybean meal yogurt.The results showed that the main up‐regulated metabolites and metabolic pathways after enzymatic digestion were dominated by amino acids and their derivatives. Conversely, the main down‐regulated metabolites and pathways were predominantly associated with flavonoid metabolism. Amino acids and their derivatives, as well as flavonoids, were found to be highly correlated with the formation of sweet, umami, astringent, and bitterness. The addition of papain enriched the content of aromatic compounds in soybean meal yogurt. Aromatic components such as 2‐heptanone, naphthalene, and p‐xylene increased in concentration. Synthetic peptide of aspartate and serine, gramine, geissospermine, N‐desmethyl vinblastine, and 3,7‐dihydroxyflavone were the major non‐volatile differential metabolites distinguishing the soybean meal yogurt.This study provided a comprehensive analysis of the metabolic traits of products co‐fermented by papain and Bifidobacterium animalis subsp. lactis, offering insights for the application of papain in fermented goods. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

A few computational studies indicated that some inhibitors of viral RNA–polymerase such as favipiravir could also inhibit cysteine proteases. The potential dual action of favipiravir as an inhibitor for both RNA–polymerase and proteases promises enhanced therapeutic efficacy of the drug against coronaviruses. To shed more light on this phenomenon, in view of the chemical structure of favipiravir and the recent advances in this field, six novel derivatives of 3-methyl quinoxaline were synthesized. In silico methods confirmed the abilities of these compounds to occupy the active-site clefts of both 3CLpro and PLpro with favorable interactions, while the ADMET evaluations predicted low toxicity and high bioavailability for them. Then, due to the high similarities between PLpro and papain, the inhibitory impacts of favipiravir and the synthesized quinoxalines on the kinetics of papain were thoroughly investigated. The outcome revealed that the potential dual-action of favipiravir-like compounds is a possibility that should be taken into account in designing more effective and safe drugs against coronavirus. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic, instigated by the emergence of the novel coronavirus, SARS-CoV-2, created an incomparable global health crisis. Due to its highly virulent nature, identifying potential therapeutic agents against this lethal virus is crucial. PLpro is a key protein involved in viral polyprotein processing and immune system evasion, making it a prime target for the development of antiviral drugs to combat COVID-19. To expedite the search for potential therapeutic candidates, this review delved into computational studies. Recent investigations have harnessed computational methods to identify promising inhibitors targeting PLpro, aiming to suppress the viral activity. Molecular docking techniques were employed by researchers to explore the binding sites for antiviral drugs within the catalytic region of PLpro. The review elucidates the functional and structural properties of SARS-CoV-2 PLpro, underscoring its significance in viral pathogenicity and replication. Through comprehensive all-atom molecular dynamics (MD) simulations, the stability of drug–PLpro complexes was assessed, providing dynamic insights into their interactions. By evaluating binding energy estimates from MD simulations, stable drug–PLpro complexes with potential antiviral properties were identified. This review offers a comprehensive overview of the potential drug/lead candidates discovered thus far against PLpro using diverse in silico methodologies, encompassing drug repurposing, structure-based, and ligand-based virtual screenings. Additionally, the identified drugs are listed based on their chemical structures and meticulously examined according to various structural parameters, such as the estimated binding free energy (ΔG), types of intermolecular interactions, and structural stability of PLpro–ligand complexes, as determined from the outcomes of the MD simulations. Underscoring the pivotal role of targeting SARS-CoV-2 PLpro in the battle against COVID-19, this review establishes a robust foundation for identifying promising antiviral drug candidates by integrating molecular dynamics simulations, structural modeling, and computational insights. The continual imperative for the improvement of existing drugs and exploring novel compounds remains paramount in the global efforts to combat COVID-19. The evolution and management of COVID-19 hinge on the symbiotic relationship between computational insights and experimental validation, underscoring the interdisciplinary synergy crucial to this endeavor. [ABSTRACT FROM AUTHOR]

Recently, jellyfish venom has gained attention as a promising reservoir of pharmacologically active compounds, with potential applications in new drug development. In this investigation, novel peptides, isolated from the hydrolysates of Nemopilema nomurai jellyfish venom (NnV), demonstrate potent inhibitory activities against angiotensin-converting enzyme (ACE). Proteolytic enzymes—specifically, papain and protamex—were utilized for the hydrolysis under optimized enzymatic conditions, determined by assessing the degree of hydrolysis through the ninhydrin test. Comparative analyses revealed that papain treatment exhibited a notably higher degree of NnV hydrolysis compared to protamex treatment. ACE inhibitory activity was quantified using ACE kit-WST, indicating a substantial inhibitory effect of 76.31% for the papain-digested NnV crude hydrolysate, which was validated by captopril as a positive control. The separation of the NnV-hydrolysate using DEAE sepharose weak-anion-exchange chromatography revealed nine peaks under a 0–1 M NaCl stepwise gradient, with peak no. 3 displaying the highest ACE inhibition of 96%. The further purification of peak no. 3 through ODS-C18 column reverse-phase high-performance liquid chromatography resulted in five sub-peaks (3.1, 3.2, 3.3, 3.4, and 3.5), among which 3.2 exhibited the most significant inhibitory activity of 95.74%. The subsequent analysis of the active peak (3.2) using MALDI–TOF/MS identified two peptides with distinct molecular weights of 896.48 and 1227.651. The peptide sequence determined by MS/MS analysis revealed them as IVGRPLANG and IGDEPRHQYL. The docking studies of the two ACE-inhibitory peptides for ACE molecule demonstrated a binding affinity of −51.4 ± 2.5 and −62.3 ± 3.3 using the HADDOCK scoring function. [ABSTRACT FROM AUTHOR]

Biomaterials, such as hydrogels, have an increasingly important role in the development of regenerative approaches for the intervertebral disc. Since animal models usually resist biomaterial injection due to high intradiscal pressure, preclinical testing of the biomechanical performance of biomaterials after implantation remains difficult. Papain reduces the intradiscal pressure, creates cavities within the disc, and allows for biomaterial injections. But papain digestion needs time, and cadaver experiments that are limited to 24 h for measuring range of motion (ROM) cannot not be combined with papain digestion just yet. In this study, we successfully demonstrate a new organ culture approach, facilitating papain digestion to create cavities in the disc and the testing of ROM, neutral zone (NZ), and disc height. Papain treatment increased the ROM by up to 109.5%, extended NZ by up to 210.9%, and decreased disc height by 1.96 ± 0.74 mm. A median volume of 0.73 mL hydrogel could be injected after papain treatment, and histology revealed a strong loss of proteoglycans in the remaining nucleus tissue. Papain has the same biomechanical effects as known from nucleotomies or herniations and thus creates a disc model to study such pathologies in vitro. This new model can now be used to test the performance of biomaterials. [ABSTRACT FROM AUTHOR]

Biogenic synthesis of papain-conjugated copper metallic Nanoparticles and their antibacterial and antifungal activities Papain metallic conjugated nanoparticles (Papain-CuNPs) were synthesised using Papain and CuSO4.5H2O. Papain-CuNPs were characterized using UV-visible spectroscopy, FT-IR (Fourier-Transform Infrared), HR-TEM (High-Resolution Transmission Electron Microscopy), XRD (X-ray diffraction), FE-SEM (Field-emission scanning electron microscopy), zeta potential, and a zeta sizer. The antibacterial activity of papain-CuNPs against human infectious microorganisms (Citrobacter spp, Pseudomonas aeruginosa and Candida albicans) was investigated. The mechanism of action of papain-CuNPs was evaluated using FE-SEM and HRTM. UV spectroscopy confirmed the plasma resonance (SPR) at 679 nm, which indicated the formation of papain-CuNPs. The FT-IR spectrum absorbance peaks at 3927, 3865, 3842, 3363, 2978, and 2900 cm-1 indicate the presence of O-H and N-H of the secondary amine, and peaks at 1643 and 1572 cm-1 represent C=O functional groups in Papain-CuNPs. EDAX analysis confirmed the presence of copper in the papain-CuNPs. The zeta potential (-42.6 mV) and zeta size (99.66 d. nm) confirmed the stability and size of the nanoparticles. XRD confirmed the crystalline nature of the papain-CuNPs. FE-SEM and HRTM showed an oval structure and the nano particles' 16.71244-34.84793 nm. The synthesized papain-NPs showed significant antibacterial activity against clinical P. aeruginosa (15 mm). MIC 125 µg/ml) showed bactericidal activity against P. aeruginosa and the mechanism of action of Papain-NPs was confirmed using an electron microscope by observing cell damage and cell shrinking. Papain-CuNPs have significant antibacterial activity and are thus used in the treatment of P. aeruginosa infections. [ABSTRACT FROM AUTHOR]

Copyright of Science & Technology of Food Industry is the property of Science & Technology of Food Industry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Biogenic synthesis of papain-conjugated copper metallic Nanoparticles and their antibacterial and antifungal activities Papain metallic conjugated nanoparticles (Papain-CuNPs) were synthesised using Papain and CuSO4.5H2O. Papain-CuNPs were characterized using UV-visible spectroscopy, FT-IR, HR-TEM, XRD, FE-SEM, zeta potential, and a zeta sizer. The antibacterial activity of papain-CuNPs against human infectious microorganisms (Citrobacter spp, Pseudomonas aeruginosa and Candida albicans) was investigated. The mechanism of action of papain-CuNPs was evaluated using FE-SEM and HRTM. UV spectroscopy confirmed the plasma resonance (SPR) at 679 nm, which indicated the formation of papain-CuNPs. The FT-IR spectrum absorbance peaks at 3927, 3865, 3842, 3363, 2978, and 2900 cm-1 indicate the presence of O-H and N-H of the secondary amine, and peaks at 1643 and 1572 cm-1 represent C=O functional groups in Papain-CuNPs. EDAX analysis confirmed the presence of copper in the papain-CuNPs. The zeta potential (-42.6 mV) and zeta size (99.66 d. nm) confirmed the stability and size of the nanoparticles. XRD confirmed the crystalline nature of the papain-CuNPs. FE-SEM and HRTM showed an oval structure, and the nano particles' 16.71244–34.84793 nm. The synthesized papain-NPs showed significant antibacterial activity against clinical P. aeruginosa (15 mm). MIC 125 µg/ml) showed bactericidal activity against P. aeruginosa and the mechanism of action of Papain-NPs was confirmed using an electron microscope by observing cell damage and cell shrinking. Papain-CuNPs have significant antibacterial activity and are thus used in the treatment of P. aeruginosa infections

Polysaccharides isolated from microalgae species have shown various biological properties. In this study, the response surface methodology (RSM) was applied to optimize the extraction conditions of crude polysaccharides from Chlorella by double enzymatic hydrolysis method (DEH). The systematic analysis of RSM revealed that the maximum yield of crude polysaccharides was obtained by adding 1.48% double enzymes (cellulose: papain = 1:1), controlling the hydrolysis temperature of 38.13 °C and pH of 5.34. Then, the crude polysaccharides were divided into three parts, named as F1, F2, and F3, using a DEAE Sepharose FF column, and the molecular weights of F1, F2, and F3 are 21.75 KDa, 1058 KDa, 5576 KDa, respectively. Monosaccharide composition analysis showed that the main constituents in F1 and F2 were Galactose (62.90% and 41.85%), while F3 was commonly composed of 39.55% Arabinose and 32.33% Rhamnose. All polysaccharides contained characteristic absorption peaks of polysaccharides with functional groups (O-H, C-H, C = O), confirming that DEH did not affect the primary structural properties of polysaccharides. Furthermore, the Chlorella polysaccharides demonstrated good thermal stability below 180 °C and perfect antioxidant properties. [ABSTRACT FROM AUTHOR]

Sous vide meat is an emerging food category, the consumption of which has increased owing to greater convenience, sensory traits, elderly consumers acceptance, and low‐cost cuts use. However, required prolonged thermal treatment to achieve desired tenderness, impact energy‐consumption besides triggering lipid oxidation, undesired off‐flavors, and cooked meat profiles. Using a response surface methodology (RSM), this study evaluated the effects of the vegetal proteolytic papain (0 to 20 mg/kg) and low‐temperature sous vide cooking (SVC) time (1 to 8 h at 65°C) in low‐value marinated M. semitendinosus beefsteaks on technological characteristics associated with tenderness, and lipid oxidation. Additionally, the sensory profile traits of the pre‐selected treatments were described using check‐all‐that‐apply (CATA) and preference mapping. Shear force (WBsSF) was reduced with greater papain addition, whereas higher cooking losses (CL) were observed with longer SVC cooking times. Both the released total collagen and TBARS values increased with increasing papain concentrations and SVC times. Combining high levels of papain (>10 mg/kg) and SVC time (>6 h) resulted in lower WBsSF values (<20 N) but higher CL (>27%) and the CATA descriptors "aftertaste" and "mushy." The optimized conditions (14 mg/kg papain; 2 h SVC) also reduced WBsSF values (<26 N) with lower CL (<20%) and were most preferred and described as "juicy" and "tender" by consumers. Observed results suggest that combined mild SVC and papain may potentiate tenderness, conjointly favor juiciness and oxidation, further representing a promising tool for reducing SVC time without compromising valued sous vide sensory traits. [ABSTRACT FROM AUTHOR]

This research consolidates our group's advances in developing a therapeutic dressing with innovative enzymatic debridement, focusing on the physicochemical and in vitro biological properties of papain immobilized in wet oxidized bacterial cellulose (OxBC–Papain) dressing. OxBC membranes were produced with Komagataeibacter hansenii oxidized with NaIO4, and papain was immobilized on them. They were characterized in terms of enzyme stability (over 100 days), absorption capacity, water vapor transmission (WVT), hemocompatibility, cytotoxicity, and cell adhesion. The OxBC–Papain membrane showed 68.5% proteolytic activity after 100 days, demonstrating the benefit of using the OxBC wet membrane for papain stability. It had a WVT rate of 678 g/m2·24 h and cell viability of 99% and 86% for L929 and HaCat cells, respectively. The membranes exhibited non-hemolytic behavior and maintained 26% clotting capacity after 1 h. The wet OxBC–Papain membrane shows significant potential as a natural biomolecule-based therapeutic dressing for wound care, offering efficient debridement, moisture maintenance, exudate absorption, gas exchange, and hemostasis without cytotoxic effects or cell adhesion to the dressing. Further research, especially using in vivo models, is needed to assess its efficacy in inducing epithelialization. This study advances stomatherapy knowledge, providing a cost-effective solution for enzymatic debridement in healthcare. [ABSTRACT FROM AUTHOR]

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Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Atherosclerosis, a noncommunicable disease caused by cholesterol plaque, can cause chronic diseases. The antiplatelet medicines used in its treatment can cause complications. Marine collagen peptides can be used as a natural atherosclerosis remedy. The present study investigated the preparation and characterization of hydrolyzed collagen (HC) from jellyfish and its conjugation with black jelly mushroom extract (BJME). Their cytotoxicity and ability to prevent cholesterol-induced endothelial cell injury were also examined. HC was prepared using Alcalase or papain hydrolysis (0.2–0.4 units/g of dry matter (DM)). Higher yield, degree of hydrolysis, and antioxidant activities (AAs) were found in the HC obtained from Alcalase, especially at 0.4 units/g DM (A-0.4), compared to other processes (p < 0.05). Thus, A-0.4 was further conjugated with BJME (1–4%, w/w of HC). The HC-2%BJME conjugate showed the highest surface hydrophobicity and AAs compared to other samples. The FTIR spectra and size distribution also confirmed the conjugation between HC and BJME. When EA.hy926 endothelial cells were treated with HC or HC-2%BJME (25–1000 µg/mL), HC-2%BJME had no cytotoxicity, whereas HC at 1000 µg/mL induced cytotoxicity (p < 0.05). Both samples also exhibited protective ability against cholesterol-induced apoptosis and VE-cadherin downregulation of cells. Therefore, HC and conjugate could be natural agents for preventing atherosclerosis. [ABSTRACT FROM AUTHOR]

Papain (PN) is a proteolytic enzyme derived from Carica Papaya L. While the pharmacological effects of PN have not been extensively studied compared to its enzymatic activity, PN also holds potential benefits beyond protein digestion. This study aimed to investigate the potential effects of PN against skin inflammation in house dust mite Dermatophagoides farinae body (Dfb)-exposed NC/Nga atopic dermatitis (AD) mice and human HaCaT keratinocytes and their underlying mechanisms. The effects of PN on the skin were assessed via histological examination, measurements of transepidermal water loss (TEWL), quantitative reverse transcription-polymerase chain reaction, Western blotting, and enzyme-linked immunosorbent assay. Our findings indicated that the oral intake of PN decreased the severity scores of lesions resembling AD, TEWL, and the levels of inflammatory cytokines and serum immunoglobulin E in Dfb-induced AD mice, along with a reduction in epidermal thickness and mast cell infiltration. Additionally, PN inhibited the activation of the mitogen-activated protein kinases (MAPKs) and the signal transducer and activator of transcription (STAT) pathways in Dfb-induced AD mice and HaCaT keratinocytes. Moreover, PN improved survival and reduced ROS production in H2O2-damaged HaCaT keratinocytes and enhanced the expression of antioxidant enzymes in Dfb-induced AD mice. Concludingly, the oral administration of PN suppressed inflammatory mediators and downregulated the MAPKs/STAT pathway, suggesting its potential role in AD pathogenesis. [ABSTRACT FROM AUTHOR]

Papain a protease enzyme naturally present in the Carica papaya has gained significant interest across several industries due to its unique properties and versatility. The unique structure of papain imparts the functionality that assists in elucidating how papain enzyme works and making it beneficial for a variety of purposes. This review highlights recent advancements in papain extraction techniques to enhance production efficiency to meet market demand. The extraction of papain from the Carica papaya plant offers various advantages such as cost‐effectiveness, biodegradability, safety, and the ability to withstand a wide range of pH and temperature conditions. Key findings reveal that non‐conventional papain extraction techniques offer significant advantages in terms of efficiency, product quality, and environmental sustainability. Furthermore, papain treatment enhances the value of final products due to its anti‐bacterial, anti‐oxidant, and anti‐obesity properties. The ability of papain to hydrolyze a wide range of proteins across various conditions makes it a suitable protease enzyme. While the study emphasizes the advantages of papain, the study also acknowledges limitations such as the continuous research and development to optimize extraction processes which will help unlock papain's potential and meet the growing demand. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Why was the work done: Gushing caused by hydrophobin originating from field fungal contamination of grain remains a significant problem in certain regions. We sought to explore whether the use of added proteinase enzymes could overcome the problem and allow the use of problematic grain. How was the work done: Four commercial proteinases were studied for their ability to digest hydrophobin and remove its foaming potential. One of those enzymes was then explored for its utility as an addition to mashing with a view to lowering the gushing potential of the ensuing beer. What are the main findings: The four enzyme preparations (Smizyme LP-G, Thermoase PC, Bromelain and Papain) were all capable of digesting hydrophobin. Of these, papain was chosen to assess whether the use of such an enzyme in mashing could ameliorate the gushing potential in finished beers. It was demonstrated that this can be achieved and without apparent detriment to the foaming potential of those beers. Why is the work important: It is now possible for brewers to consider an alternative approach to rectifying gushing risks if they are confronted with problematic grain. It must be stressed that this technique will not address the other main risk from infections of this type, namely the production of mycotoxins. Even in a context where gushing is not a problem, this work has indicated that there should be little concern with addition of papain at the mashing stage from a perspective of decreasing the foaming performance of beer. [ABSTRACT FROM AUTHOR]

The management of acute and chronic wounds has a significant financial, clinical, social impact on healthcare and affects the living conditions of over 2.5% of the population. Despite the numerous treatments, already established, for both chronic and acute wounds, their management continues to constitute an urgent and burdensome issue in modern times, necessitating the development of novel therapies. The most powerful catalysts found in nature are enzymes. Proteases are among the most highly lucrative commercial enzymes and account for around 60% of the entire enzyme market. The first protein to be obtained from papaya and the first cysteine protease whose three-dimensional X-ray analysis showed its structure was papain. As a result, cysteine proteases, a major category of essential substances, are acknowledged as pa-pain-like proteins. Thus, papaya (Carica papaya) and mountain papaya (Vasconcellea cundinamarcensis) both contain the cysteine protease enzyme known as papain, also referred to as papaya proteinase I. This mini review's objective is to look into the recent literature for healing properties of papain attributed to its bactericidal and anti-inflammatory action. [ABSTRACT FROM AUTHOR]

The objective of this work was to assess the efficacy of different proteolytic agents on the bond strength of pit and fissure sealants to bovine enamel. Eighty-four bovine enamel specimens were randomly assigned in groups according to the pit and fissure sealant applied (HelioSeal F or Dyad Flow). Then, the specimens were subdivided according to the proteolytic agent used (n = 7): Group 1, distilled water (control); Group 2, 10 wt.% Tergazyme®; Group 3, 10 wt.% ZYME®; Group 4, 10% papain gel; Group 5, 10% bromelain gel; and Group 6, 5.25 wt.% sodium hypochlorite. The cell viability of the proteolytic solutions was assessed through the MTT assay. The proteolytic agents were applied on the enamel surface prior to the acid-etching procedure; then, the pit and fissure sealants were placed. The micro-shear bond strength was evaluated after 24 h or 6 months of water storing at 37 °C. Representative SEM images were taken for each experimental group. The bond strength data were statistically analyzed by a three-way ANOVA test using a significance level of α = 0.05. Bromelain and papain proteolytic solutions did not exert any cytotoxic effect on the human dental pulp cells. After 24 h and 6 months of aging, for both pit and fissure sealants, sodium hypochlorite, papain, bromelain, and Tergazyme® achieved statistically significant higher bond strength values (p < 0.05). Irrespective of the deproteinizing agent used, Dyad Flow resulted in a better bond strength after 6 months of aging. The type 1 etching pattern was identified for sodium hypochlorite, papain, and bromelain. Tergazyme®, papain, and bromelain demonstrated efficacy in deproteinizing enamel surfaces prior to acid etching, leading to the improved bond strength of pit and fissure sealants. Clinically, this suggests that these proteolytic agents can be considered viable alternatives to traditional methods for enhancing sealant retention and longevity. Utilizing these agents in dental practice could potentially reduce sealant failures. [ABSTRACT FROM AUTHOR]

A variety of parameters, including liquefaction and semen viscosity, affect the sperm's ability to travel and reach the egg for fertilization and conception. Given that the details behind the viscosity of the semen in male camels have not yet been fully clarified, the purpose of this study was to ascertain how the addition of papain affected the viscosity of fresh diluted camel semen. The study examined semen samples derived from camels that had distinct viscosities. Sperm motility, viability, abnormal sperm percentage, concentration, viscosity, morphometry, acrosome integrity and liquefaction were among the evaluations following 0, 5, 10, 20 or 30 min of incubation at 37°C with papain (0.004 mg/mL, 0.04 mg/mL or 0.4 mg/mL; a semen sample without papain was used as a control). A statistically significant interaction between the effects of papain concentrations and incubation time was found (F = 41.68, p =.0001). Papain concentrations (p =.0001) and incubation times (p =.0001) both had a statistically significant impact on viscosity, according to a simple main effects analysis. A lower viscosity was found (p <.05) at 0.04 mg/mL (0.1 ± 0.0) after 10 min of incubation. A simple main effects analysis showed that papain concentrations and incubation time have a statistically significant effect on sperm motility (p =.0001). At 0.04 mg/mL papain, the sperm motility % was higher (p <.05) after 10 min (64.4 ± 4.8), 20 min (68.4 ± 6.2), and 30 min incubation (72.2 ± 6.6) compared to 0, 5 min (38.3 ± 4.1 and 51.6 ± 5.0, respectively). In conclusion, the fresh diluted camel semen had the lowest viscosity properties after 10 min of incubation with 0.04 mg/mL papain, without compromising sperm motility, viability, acrosome integrity and sperm morphology. [ABSTRACT FROM AUTHOR]

Copyright of Indonesian Fisheries Processing Journal / Jurnal Pengolahan Hasil Perikanan Indonesia is the property of IPB University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study explored the inhibitory potential of gallium maltolate against severe acute respiratory syndrome coronavirus 2 and main and papain-like proteases. Computational methods, including density functional theory and molecular docking, were used to assess gallium maltolate reactivity and binding interactions. Density functional theory calculations revealed gallium maltolate's high electron-capturing capacity, particularly around the gallium metal atom, which may contribute to their activity. Molecular docking demonstrated that gallium maltolate can form strong hydrogen bonds with key amino acid residues like glutamate-166 and cysteine-145, tightly binding to main and papain-like proteases. The binding energy and interactions of gallium maltolate were comparable to known SARS-CoV-2 inhibitors like N-[(5-methyl-1,2-oxazol-3-yl)carbonyl]-L-alanyl-L-valyl-N-{(2S,3E)-5-(benzyloxy)-5-oxo-1-[(3S)-2-oxopyrrolidin-3-yl]pent-3-en-2-yl}-L-leucinamide, indicating its potential as an antiviral agent. However, further experimental validation is required to confirm its effectiveness in inhibiting SARS-CoV-2 replication and treating COVID-19. [ABSTRACT FROM AUTHOR]

Eggs of dumbo catfish are known to stick to the substrate due to the presence of a mucus layer, which causes suboptimal oxygen supply and low hatching percentage. This indicates that the mucus layer must be lowered while eliminating the need for a substrate during hatching. One of the natural ingredients that can be used for this purpose is papaya leaf, which contains the proteolytic enzyme papain. Therefore, this study aims to determine the effect of papaya leaf solution on the percentage of live embryos after soaking, hatching percentage, hatching time, survival rate, and abnormality percentage of dumbo catfish larvae. This research was carried out at the Basic Fisheries Laboratory, Aquaculture Study Program, Fisheries Department, Faculty of Agriculture, Sriwijaya University in August-October 2022. A Completely Randomized Design (CRD) was used, which consisted of four treatments and three repetitions. The treatment given was the soaking of eggs in papaya leaf solution with different concentrations of (P0/control), 2 g/0.96 L (P1), 4 g/0.96 L (P2), and 6 g/0.96 L (P3). The results showed that P2 was the best treatment with 100% live embryos after soaking, 94.06% hatching percentage, 20.24 hours hatching time, 92.78% survival rate, and 0.93% abnormality percentage. Based on these results, the soaking of dumbo catfish eggs in papaya leaf solution could increase the hatching percentage and survival rate. [ABSTRACT FROM AUTHOR]

Abstract The study examined the efficacy of freeze-dried papain enzyme obtained from three Vasconcellea species (V. pubescens, V. chachapoyensis, V. heilbornii) as a natural coagulant in cheese making. Notably, the enzyme V. pubescens demonstrated the most promising results when concentrations of 2 g/L, 4 g/L, and 6 g/L were used to produce fresh cheese, while other enzyme species exhibited lower efficacy. The optimal yield of fresh cheese with minimal residual enzyme was achieved when a 2 g/L dose of papain enzyme was employed at a coagulation temperature of 30 °C, resulting in physicochemical and organoleptic characteristics comparable to those produced with commercial Hansen’s rennet. Nevertheless, an increase in the coagulation temperature (42 °C) and a higher dose of papain enzyme (4 g/L) resulted in a reduction in the yield of fresh cheese and; consequently, the residual enzyme increased. Further studies are required to determine the purity of freeze-dried papain and the most effective dosage to increase profitability for producers and consumers. Such findings could facilitate the ecological application of this alternative in producing of fresh cheese.

The prevalence of chronic kidney disease (CKD) is increasing, affecting more than 10 % of the global population. In addition, subclinical inflammation associated with COVID-19 infection leads to a progressive decline in kidney function, resulting in chronic kidney disease. Early intervention in candidates with early-stage CKD may delay, or avert, progression to end-stage complications. It is widely accepted that serum Cystatin C is a reliable and early indicator of CKD. Urinary Cystatin C tends to increase with the progression of kidney malfunctioning. Thus, early detection can lower the morbidity and mortality associated with CKD. This study includes the design of a proteotronic platform for the rapid detection of CKD. Here, we have developed a biosensor that is highly specific to Cystatin C and shows a negligible response to other urinary biomarkers. The sensitivity of the biosensor was 50889.6 µA cm−2 mg−1 and the limit of detection for Cystatin C in the sample was calculated as 26 ng mL−1. The stability of the biosensor was studied by measuring the change inthe differential pulse voltammetric current at every month of storage at 4 °C. The biosensor was established to be stable for 12 months, with approximately 10 % loss in the preliminary peak current (Ip) value with storage at 4 °C. Thus, the fabricated proteotronic biosensor exhibited an analytical yet simple approach for point of care diagnostics (POCD) of CKD. The developed POCD is economical and proficient, and will enable CKD management in non-hospitalized patients.

Direct-acting antivirals are needed to combat coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). The papain-like protease (PLpro) domain of Nsp3 from SARS-CoV-2 is essential for viral replication. In addition, PLpro dysregulates the host immune response by cleaving ubiquitin and interferon-stimulated gene 15 protein from host proteins. As a result, PLpro is a promising target for inhibition by small-molecule therapeutics. Here we design a series of covalent inhibitors by introducing a peptidomimetic linker and reactive electrophile onto analogs of the noncovalent PLpro inhibitor GRL0617. The most potent compound inhibits PLpro with kinact/KI = 9,600 M-1 s-1, achieves sub-μM EC50 values against three SARS-CoV-2 variants in mammalian cell lines, and does not inhibit a panel of human deubiquitinases (DUBs) at >30 μM concentrations of inhibitor. An X-ray co-crystal structure of the compound bound to PLpro validates our design strategy and establishes the molecular basis for covalent inhibition and selectivity against structurally similar human DUBs. These findings present an opportunity for further development of covalent PLpro inhibitors.

The worldwide COVID-19 pandemic caused by the coronavirus SARS-CoV-2 urgently demands novel direct antiviral treatments. The main protease (Mpro) and papain-like protease (PLpro) are attractive drug targets among coronaviruses due to their essential role in processing the polyproteins translated from the viral RNA. In this study, we virtually screened 688 naphthoquinoidal compounds and derivatives against Mpro of SARS-CoV-2. Twenty-four derivatives were selected and evaluated in biochemical assays against Mpro using a novel fluorogenic substrate. In parallel, these compounds were also assayed with SARS-CoV-2 PLpro. Four compounds inhibited Mpro with half-maximal inhibitory concentration (IC50) values between 0.41 μM and 9.0 μM. In addition, three compounds inhibited PLpro with IC50 ranging from 1.9 μM to 3.3 μM. To verify the specificity of Mpro and PLpro inhibitors, our experiments included an assessment of common causes of false positives such as aggregation, high compound fluorescence, and inhibition by enzyme oxidation. Altogether, we confirmed novel classes of specific Mpro and PLpro inhibitors. Molecular dynamics simulations suggest stable binding modes for Mpro inhibitors with frequent interactions with residues in the S1 and S2 pockets of the active site. For two PLpro inhibitors, interactions occur in the S3 and S4 pockets. In summary, our structure-based computational and biochemical approach identified novel naphthoquinonal scaffolds that can be further explored as SARS-CoV-2 antivirals.

A combined pretreatment method of "low temperature-ultrasound-papain" (LTUP) was proposed to remove the purine of pork loins. Compared with untreated pork loin, under optimal conditions (temperature 58 °C, ultrasound density 100 W/cm2, and papain concentration 0.085%), the purine removal rate of treated pork loin could reach 59.29 ± 1.39%. The meat quality of pork loin treated with the LTUP method such as hardness and chewiness decreased by 58.37% and 64.38%, respectively, and the in vitro protein digestibility was increased by 19.64%; the cooking loss was decreased by 15.45%, compared with the simulated household blanching process (HT). In view of the high purine removal rate, the losses of free amino acids and soluble peptides were acceptable and reasonable. SEM and LF-NMR results showed that low temperature and ultrasound combined with papain treatment opened a channel for purine transfer and promoted purine dissolution by affecting the protein structure of pork loin. In addition, the migration of water within the muscle tissue was also related to purine removal. In summary, LTUP is recommended as an efficient and green way for the meat industry to remove purine. [ABSTRACT FROM AUTHOR]

Pure polypyrrole (ppy) doped with different weight percent of papain was synthesized by in situ polymerization. These different compositions of pyrrole and papain composite polymers were analyzed for direct current (DC) conductivity. The size of the particle calculated by using the Scherrer equation and Williamson-Hall (W-H) plot was found to be in the range of 15 nm -- 20 nm. Activation energies evaluated by using Arrhenius plots show an increase in activation energy from base ppy to papain-ppy composite polymer. The activation energy was found to vary from 22.4 meV to 34.4 meV for papain-ppy composite. The experiment revealed that Mott's Variable Range Hopping model (VRH) for three dimensions (3D) applies to pure polypyrrole and papain-ppy composite. The density of states at the Fermi level N(EF) were found to be 2.7 x 1021 eV-1cm-1 for pure ppy and ranged from 0.3 x 1019 eV-1cm-1 to 0.8 x 1020 eV-1cm-1 for the composite polymer. The average hopping range and average hopping energy of pure ppy and composite polymers were also calculated. [ABSTRACT FROM AUTHOR]

Calcium peptide chelates are developed as efficient supplements for preventing calcium deficiency. Spent hen meat (SHM) contains a high percentage of proteins but is generally wasted due to the disadvantages such as hard texture. We chose the underutilized SHM to produce peptides to bind calcium by proteolysis and aimed to investigate chelation between calcium and peptides in hydrolysate for a sustainable purpose. The optimized proteolysis conditions calculated from the result of response surface methodology for two‐step hydrolysis were 0.30% (wenzyme/wmeat) for papain with a hydrolysis time of 3.5 h and 0.18% (wenzyme/wmeat) for flavourzyme with a hydrolysis time of 2.8 h. The enzymatic hydrolysate (EH) showed a binding capacity of 63.8 ± 1.8 mg calcium/g protein. Ethanol separation for EH improved the capacity up to a higher value of 68.6 ± 0.6 mg calcium/g protein with a high association constant of 420 M−1 (25°C) indicating high stability. The separated fraction with a higher amount of Glu, Asp, Lys, and Arg had higher calcium‐binding capacity, which was related to the number of ─COOH and ─NH2 groups in peptide side chains according to the result from amino acid analysis and Fourier transform infrared spectroscopy. Two‐step enzymatic hydrolysis and ethanol separation were an efficient combination to produce peptide mixtures derived from SHM with high calcium‐binding capacity. The high percentage of hydrophilic amino acids in the separated fraction was concluded to increase calcium‐binding capacity. This work provides foundations for increasing spent hen utilization and developing calcium peptide chelates based on underutilized meat. [ABSTRACT FROM AUTHOR]