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Typical Kunitz proteins (I2 family of the MEROPS database, Kunitz-A family) are metazoan competitive inhibitors of serine peptidases that form tight complexes of 1:1 stoichiometry, mimicking substrates. The cestode Echinococcus granulosus, the dog tapeworm causing cystic echinococcosis in humans and livestock, encodes an expanded family of monodomain Kunitz proteins, some of which are secreted to the dog host interface. The Kunitz protein EgKU-7 contains, in addition to the Kunitz domain with the anti-peptidase loop comprising a critical arginine, a C-terminal extension of ∼20 amino acids. Kinetic, electrophoretic, and mass spectrometry studies using EgKU-7, a C-terminally truncated variant, and a mutant in which the critical arginine was substituted by alanine, show that EgKU-7 is a tight inhibitor of bovine and canine trypsins with the unusual property of possessing two instead of one site of interaction with the peptidases. One site resides in the anti-peptidase loop and is partially hydrolyzed by bovine but not canine trypsins, suggesting specificity for the target enzymes. The other site is located in the C-terminal extension. This extension can be hydrolyzed in a particular arginine by cationic bovine and canine trypsins but not by anionic canine trypsin. This is the first time to our knowledge that a monodomain Kunitz-A protein is reported to have two interaction sites with its target. Considering that putative orthologs of EgKU-7 are present in other cestodes, our finding unveils a novel piece in the repertoire of peptidase-inhibitor interactions and adds new notes to the evolutionary host-parasite concerto.

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Recent advancements in enzyme research have unveiled a new proteoform of bovine trypsin, expanding our understanding of this well-characterized enzyme. While generally similar to other trypsins, this novel proteoform comprises three polypeptide chains, marking a significant difference in activity, kinetic properties, and conformational stability. Compared with the already known bovine trypsin proteoforms, the results showed a lower: activity, kcat and kcat.KM-1 and protein 'foldedness' ratio for the new proteoform. Molecular autolysis, a common feature in trypsin and chymotrypsin, has been explored through comparative physical chemistry properties with other proteoforms. This new proteoform of trypsin not only enriches the existing enzyme repertoire but also promises to shed light on the intricate physiological pathway for enzyme inactivation. Our results suggest that the new trypsin proteoform is one of the likely final pathways for enzyme inactivation in a physiological environment. This discovery opens up new avenues for further research into the functional implications of this new trypsin proteoform.

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This study presents an innovative method for synthesizing ß-amino carbonylated compounds, specifically 2-[phenyl(phenylamino)methyl] cyclohexanone, achieving high conversions and diastereomeric ratios. Using trypsin or α-chymotrypsin in both free and immobilized forms on titanate nanotubes (NtsTi), synthesized through alkaline hydrothermal methods, successful immobilization yields were attained. Notably, α-chymotrypsin, when free, displayed a diastereoselective synthesis of the anti-isomer with 97 % conversion and 16 : 84 (syn : anti) diastereomeric ratio, which slightly decreased upon immobilization on NtsTi. Trypsin, in its free form, exhibited diastereoselective recognition of the syn-isomer, while immobilization on NtsTi (trypsin/NtsTi) led to an inversion of diastereomeric ratio. Both trypsin/NtsTi and α-chymotrypsin/NtsTi demonstrated significant catalytic efficiency over five cycles. In conclusion, NtsTi serves as an effective support for trypsin and α-chymotrypsin immobilization, presenting promising prospects for diastereoselective synthesis and potential industrial applications. Furthermore, it offers promising prospects for the diastereoselective synthesis of 2-[phenyl(phenylamino)methyl] cyclohexanone through multicomponent Mannich reaction and future industrial application.

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INTRODUCTION: Trypsin inhibitors (TIs) have the ability to competitively or non-competitively bind to trypsin and inhibit its action. These inhibitors are commonly found in plants and are used in protease inhibition studies involved in biochemical pathways of pharmacological interest. OBJECTIVES: This work aimed to purify a trypsin inhibitor from Bauhinia pulchella seeds (BpuTI), describing its kinetic mechanism and anticoagulant effect. METHODS: Affinity chromatography, protein assay, and SDS-PAGE were used to purify the inhibitor. Mass spectrometry, inhibition assays, and enzyme kinetics were used to characterize the inhibitor. In vitro assays were performed to verify its ability to prolong blood clotting time. RESULTS: Affinity chromatography on a Trypsin-Sepharose 4B column gave a yield of 43.1. BpuTI has an apparent molecular mass of 20 kDa with glycosylation (1.15%). Protein identification was determined by MS/MS, and BpuTI showed similarity to several Kunitz-type trypsin inhibitors. BpuTI inhibited bovine trypsin as an uncompetitive inhibitor with IC50 (3 x 10-6 M) and Ki (1.05 x 10-6 M). Additionally, BpuTI showed high stability to temperature and pH variations, maintaining its activity up to 100ºC and in extreme pH ranges. However, the inhibitor was susceptible to reducing agents, such as DTT, which completely abolished its activity. BpuTI showed an anticoagulant effect in vitro at a concentration of 33 µM, prolonging clotting time by 2.6 times. CONCLUSION: Our results suggest that BpuTI can be a biological tool to be used in blood clotting studies.

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Introducción: la fibrosis quística (FQ) es una enfermedad genética, multisistémica, caracterizada por la disfunción de las glándulas de secreción exocrina secundaria a la mutación de una proteína transmembrana que actúa como canal de cloro. La inclusión de su búsqueda en el Sistema Nacional de Pesquisa Neonatal (SNPN) determinó un gran impacto sobre la morbimortalidad de esta enfermedad, permitiendo un diagnóstico y tratamiento precoz. El íleo meconial (IM) es la manifestación más precoz de la enfermedad, ocurriendo en un 10% a 18% de los pacientes. Objetivo: describir una forma de presentación precoz de FQ con resultado de pesquisa neonatal normal. Caso clínico: 18 meses. Sexo femenino; 33 semanas de edad gestacional. Retraso en la expulsión del meconio. Al tercer día de vida íleo meconial con oclusión intestinal, vólvulo de intestino medio y necrosis intestinal. Se realiza resección quirúrgica. Tripsina inmunorreactiva (TIR) normal a los 7 y 23 días de vida. No se solicita proteína asociada a la pancreatitis (PAP). Desnutrición crónica, bronquiolitis grave a los 3 meses, neumonías virales a los 7 y 11 meses. Ingreso con diagnóstico de neumonía aguda comunitaria con insuficiencia respiratoria. Test del sudor alterado en dos oportunidades. Elastasa pancreática insuficiente. Se aísla Staphylococcus aureus y Pseudomonas aeruginosa en exudado nasal y de secreciones respiratorias. Estudio genético: mutación Delta F508. Con diagnóstico de FQ se inició abordaje multidisciplinario, tratamiento y derivación al centro especializado. Conclusiones: la existencia de IM puede dar falsos negativos en el valor de la TIR, siendo necesaria la dosificación de la PAP. El pronóstico de estos pacientes va a depender de un diagnóstico precoz y el manejo terapéutico oportuno en centros especializados.

Introduction: cystic fibrosis (CF) is a genetic, multisystemic disease, characterized by dysfunction of the exocrine secretion glands secondary to the mutation of a transmembrane protein that acts as a chloride channel. Including its research by the National Neonatal Screening System (SNPN) caused a great impact on the morbidity and mortality of this disease, enabling early diagnosis and treatment. Meconium ileus (MI) is the earliest manifestation of the disease, occurring in 10% to 18% of patients. Objective: to describe a form of early presentation of CF with normal neonatal screening results. Clinical case: 18 months. Female, 33 weeks gestational age. Delay in the expulsion of meconium. On the third day of life, meconium ileus with intestinal obstruction, midgut volvulus and intestinal necrosis. Surgical resection is performed. Trypsin immunoreactive (TIR) normal at 7 and 23 days of age. Pancreatitis-associated protein (PAP) is not requested. Chronic malnutrition, severe bronchiolitis at 3 months, viral pneumonia at 7 and 11 months. Admission with a diagnosis of acute community pneumonia with respiratory failure. Sweat test altered on two occasions. Insufficient pancreatic elastase. Staphylococcus aureus and Pseudomonas aeruginosa were isolated in nasal exudate and respiratory secretions. Genetic study: Delta F508 mutation. With the CF diagnosis, a multidisciplinary approach, treatment and referral to a specialized center began. Conclusions: the existence of MI can provide false negatives in the IRR value, making PAP dosage necessary. The prognosis of these patients will depend on early diagnosis and timely therapeutic management at specialized centers.

Introdução: a fibrose cística (FC) é uma doença genética, multissistêmica, caracterizada pela disfunção das glândulas secretoras exócrinas secundária à mutação de uma proteína transmembrana que age como canal de cloreto. A inclusão da sua pesquisa no Sistema Nacional de Triagem Neonatal (SNPN) determinou grande impacto na morbimortalidade desta doença, permitindo diagnóstico e tratamento precoces. O íleo meconial (IM) é a manifestação mais precoce da doença, ocorrendo em 10 a 18% dos pacientes. Objetivo: descrever uma forma de apresentação precoce da FC com resultados normais de triagem neonatal. Caso clínico: 18 meses. Sexo feminino. 33 semanas de idade gestacional. Atraso na expulsão do mecônio. No terceiro dia de vida, íleo meconial com obstrução intestinal, vólvulo de intestino médio e necrose intestinal. A ressecção cirúrgica é realizada. Imunorreativo à tripsina (TIR) normal aos 7 e 23 dias de vida. A proteína associada à pancreatite (PAP) não é solicitada. Desnutrição crônica, bronquiolite grave aos 3 meses, pneumonia viral aos 7 e11 meses. Internação com diagnóstico de pneumonia comunitária aguda com insuficiência respiratória. Teste do suor alterado em duas ocasiões. Elastase pancreática insuficiente. Staphylococcus aureus e Pseudomonas aeruginosa foram isolados em exsudato nasal e secreções respiratórias. Estudo genético: mutação Delta F508. Com o diagnóstico de FC iniciou-se abordagem multidisciplinar, tratamento e encaminhamento para centro especializado. Conclusões: a existência de IM pode dar falsos negativos no valor da TIR, tornando necessária a dosagem de PAP. O prognóstico destes pacientes dependerá do diagnóstico precoce e do manejo terapêutico oportuno em centros especializados.

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Proteases are the main enzymes traded worldwide-comprising 60% of the total enzyme market-and are fundamental to the degradation and processing of proteins and peptides. Due to their high commercial demand and biological importance, there is a search for alternative sources of these enzymes. Crotalaria stipularia is highlighted for its agroecological applications, including organic fertilizers, nematode combat, and revegetation of areas contaminated with toxic substances. Considering the pronounced biotechnological functionality of the studied species and the necessity to discover alternative sources of proteases, we investigated the extraction, purification, and characterization of a protease from seeds of the C. stipularia plant. Protease isolation was achieved by three-phase partitioning and single-step molecular exclusion chromatography in Sephacryl S-100, with a final recovery of 47% of tryptic activity. The molecular mass of the isolated enzyme was 40 kDa, demonstrating optimal activities at pH 8.0 and 50 °C. Enzymatic characterization demonstrated that the protease can hydrolyze the specific trypsin substrate, BApNA. This trypsin-like protease had a Km, Vmax, Kcat, and catalytic efficiency constant of 0.01775 mg/mL, 0.1082 mM/min, 3.86 s-1, and 217.46, respectively.

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This study aimed to immobilize trypsin on activated carbon submitted to different surface modifications and its application in casein hydrolysis. With the aim of determining which support can promote better maintenance of the immobilized enzyme. Results showed that pH 5.0 was obtained as optimal for immobilization and pH 9.0 for the casein hydrolysis reaction for activated carbon and glutaraldehyde functionalized carbon. Among the supports used, activated carbon modified with iron ions in the presence of a chelating agent was the one that showed best results, under the conditions evaluated in this study. Presenting an immobilization yield of 95.15% and a hydrolytic activity of 4.11 U, same as soluble enzyme (3.76 U). This derivative kept its activity stable at temperatures above 40 °C for1 h and when stored for 30 days at 5 °C. Furthermore, it was effective for more than 6 reuse cycles (under the same conditions as the 1st cycle). In general, immobilization of trypsin on metallized activated carbon can be an alternative to biocatalysis, highlighting the advantages of protease immobilization.

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Ganoderma lucidum is a medicinal mushroom widely recognized as a source of biomolecules with pharmacological properties, however, little is known about the factors that influence the synthesis of bioactive proteins by this fungus when cultivated under submerged fermentation. The objective of this work was to evaluate the production of mycelial biomass and intracellular proteases and protease inhibitors by G. lucidum cultivated under different submerged fermentation conditions. The cultivation was carried out in a medium composed of glucose (10 or 20 g.L-1), soy peptone (2.5 or 5 g.L-1) and yeast extract (5 g.L-1), with incubation under agitation (120 rpm) and non-agitation, totaling 8 experimental conditions. Biomass production was determined from the dry weight, while glucose consumption was estimated by quantification of reducing sugars. The proteins were extracted in NaCl (0.15 M), and the protein extracts were submitted to protein quantification by the Bradford method, total proteolytic activity using azocasein, caseinolytic and fibrinolytic activity in Petri dishes, activity of serine (trypsin and chymotrypsin) and cysteine (papain) protease inhibitors. Cultivation in agitated condition showed higher biomass production with a maximum value of 7 g.L-1, in addition to higher activities of trypsin, chymotrypsin and papain inhibitors, with 154 IU.mg-1, 153 IU.mg-1 e 343 IU.mg-1 of protein, respectively. The non-agitated condition showed a greater potential for obtaining proteins, total proteases, caseinolytic and fibrinolytic enzymes, with maximum values of 433 mg.g-1 of extract, 71 U.mL-1 of extract, 63.62 mm2 and 50.27 mm2, respectively. Thus, a medium composed of soy peptone, yest extract and glucose in a 1:2:4 proportion is recommended, under agitation to produce protease inhibitors, and the non-agitated condition when the target is, mainly caseinolytic and fibrinolytic enzymes.

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Proteases such as trypsins in the gut of Spodoptera frugiperda are responsible for breaking down dietary proteins into amino acids necessary for insect growth and development. In this study, we characterized the insecticidal potential of dioscorin, the storage protein of yam (Dioscorea alata), using molecular docking and molecular dynamics simulations to determine the interactions between trypsin enzymes and the protein inhibitor dioscorin. To achieve this, we used the three-dimensional structures of the trypsin-like digestive enzymes of S. frugiperda, a pest of corn and cotton, as receptors or target molecules. We performed protein-protein docking using Cluspro software, estimation of the binding free energy, and information on the dynamic and time-dependent behavior of dioscorin-trypsin complexes using the NAMD package. Our computational analysis showed that dioscorin can bind to the digestive trypsins of S. frugiperda, as confirmed by the affinity energy values (-1022.4 to -1236.9), stability of the complexes during the simulation trajectory, and binding free energy values between -57.3 and -66.9 kcal/mol. Additionally, dioscorin uses two reactive sites to bind trypsin, but the largest contribution to the interaction energy is made by amino acid residues between amino acid backbone positions 8-14 by hydrogen bonds, hydrophobic, and Van der Waals (VdW) interactions. VdW is the energy that makes the greatest contribution to the binding energy. Collectively, our findings demonstrate, for the first time, the binding capacity of the yam protein dioscorin to the digestive trypsin of S. frugiperda. These promising results suggest a possible bioinsecticide action of dioscorin.

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Enterotoxemia caused by Clostridium perfringens type D usually affects sheep and goats ≥ 2-wk-old. The main clinical signs and lesions of the disease are produced by the epsilon toxin (ETX) elaborated by this microorganism. However, ETX is produced in the form of a mostly inactive prototoxin that requires protease cleavage for activation. It has traditionally been believed that younger animals are not affected by type D enterotoxemia given the low trypsin activity in the intestinal content associated with the trypsin-inhibitory action of colostrum. Two Nigerian dwarf goat kids, 2- and 3-d-old, with a history of acute diarrhea followed by death, were submitted for postmortem examination and diagnostic workup. Autopsy and histopathology revealed mesocolonic edema, necrosuppurative colitis, and protein-rich pulmonary edema. Alpha toxin and ETX were detected in intestinal content, and C. perfringens type D was isolated from the colon of both animals. The isolates encoded the gene for lambda toxin, a protease that has been shown previously to activate ETX in vitro. Type D enterotoxemia has not been reported previously in neonatal kids, to our knowledge, and we suggest that lambda toxin activated the ETX.

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