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Li Z, Liu T, Fan K, Geng L, Wang P, Ren F, Luo J. Preparation of pH-responsive chitosan microspheres containing aminopeptidase and their application in accelerating cheese ripening. J Dairy Sci 2024; 107:3502-3514. [PMID: 38246547 DOI: 10.3168/jds.2023-23982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 12/21/2023] [Indexed: 01/23/2024]
Abstract
Microencapsulated enzymes have been found to effectively accelerate cheese ripening. However, microencapsulated enzyme release is difficult to control, often resulting in enzyme release during cheese processing and causing texture and flavor defects. This study aims to address this issue by developing aminopeptidase-loaded pH-responsive chitosan microspheres (A-CM) for precise enzyme release during cheese ripening. An aminopeptidase with an isoelectric point (pH 5.4) close to the pH value of cheese ripening was loaded on chitosan microspheres through electrostatic interaction. Turbidity titration measurements revealed that pH 6.5 was optimal for binding aminopeptidase and microspheres, affording the highest loading efficiency of 58.16%. Various characterization techniques, including scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy confirmed the successful loading of aminopeptidase molecules on the chitosan microspheres. In vitro release experiments conducted during simulated cheese production demonstrated that aminopeptidase release from A-CM was pH responsive. The microspheres retained the enzyme during the coagulation and cheddaring processes (pH 5.5-6.5) and only released it after entering the cheese-ripening stage (pH 5.0-5.5). By loading aminopeptidase on chitosan microspheres, the loss rate of the enzyme in cheese whey was reduced by approximately 79%. Furthermore, compared with cheese without aminopeptidase and cheese with aminopeptidase added directly, the cheeses made with A-CM exhibited the highest proteolysis level and received superior sensory ratings for taste and smell. The content of key aroma substances, such as 2/3-methylbutanal and ethyl butyrate, in cheese with A-CM was more than 15 times higher than the others. This study provides an approach for accelerating cheese ripening through the use of microencapsulated enzymes.
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Affiliation(s)
- Zhixi Li
- College of Food Science and Technology, Hunan Agricultural University, Changsha 410114, China
| | - Tianshu Liu
- Key Laboratory of Functional Dairy, Co-constructed by Ministry of Education and Beijing Government, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Ke Fan
- College of Food Science and Technology, Hunan Agricultural University, Changsha 410114, China
| | - Lanlan Geng
- College of Food Science and Technology, Hunan Agricultural University, Changsha 410114, China
| | - Pengjie Wang
- Key Laboratory of Functional Dairy, Co-constructed by Ministry of Education and Beijing Government, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Fazheng Ren
- Key Laboratory of Functional Dairy, Co-constructed by Ministry of Education and Beijing Government, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Jie Luo
- College of Food Science and Technology, Hunan Agricultural University, Changsha 410114, China; Key Laboratory of Functional Dairy, Co-constructed by Ministry of Education and Beijing Government, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
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Olajide JS, Xiong L, Yang S, Qu Z, Xu X, Yang B, Wang J, Liu B, Ma X, Cai J. Eimeria falciformis secretes extracellular vesicles to modulate proinflammatory response during interaction with mouse intestinal epithelial cells. Parasit Vectors 2022; 15:245. [PMID: 35804396 PMCID: PMC9270845 DOI: 10.1186/s13071-022-05364-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 06/15/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Protozoan parasite secretions can be triggered by various modified media and diverse physicochemical stressors. Equally, host-parasite interactions are known to co-opt the exchange and secretion of soluble biochemical components. Analysis of Eimeria falciformis sporozoite secretions in response to interaction with mouse intestinal epithelial cells (MIECs) may reveal parasite secretory motifs, protein composition and inflammatory activities of E. falciformis extracellular vesicles (EVs). METHODS Eimeria falciformis sporozoites were allowed to interact with inactivated MIECs. Parasite secretions were separated into EV and vesicle-free (VF) fractions by discontinuous centrifugation and ultracentrifugation. Secreted EVs were purified in an iodixanol density gradient medium and the protein composition of both EV and VF fractions were analyzed by liquid chromatoraphy-tandem mass spectroscopy. The inflammatory activities of E. falciformis sporozoite EV on MIECs were then investigated. RESULTS During the interaction of E. falciformis sporozoites with inactivated MIECs, the parasite secreted VF and vesicle-bound molecules. Eimeria falciformis vesicles are typical pathogenic protozoan EVs with a mean diameter of 264 ± 2 nm, and enclosed heat shock protein (Hsp) 70 as classical EV marker. Refractile body-associated aspartyl proteinase (or eimepsin), GAP45 and aminopeptidase were the main components of E. falciformis sporozoite EVs, while VF proteins include Hsp90, actin, Vps54 and kinases, among others. Proteomic data revealed that E. falciformis EV and VF proteins are aggregates of bioactive, antigenic and immunogenic molecules which act in concert for E. falciformis sporozoite motility, pathogenesis and survival. Moreover, in MIECs, E. falciformis EVs induced upregulation of gene expression and secretion of IL-1β, IL-6, IL-17, IL-18, MCP1 as well as pyroptosis-dependent caspase 11 and NLRP6 inflammasomes with the concomitant secretion of lactate dehydrogenase. CONCLUSIONS Eimeria falciformis sporozoite interaction with MIECs triggered the secretion of immunogenic and antigenic proteins. In addition, E. falciformis sporozoite EVs constitute parasite-associated molecular pattern that induced inflammatory response and cell death. This study offers additional insight in the secretion and protein composition of E. falciformis secretomes as well as the proinflammatory functions of E. falciformis sporozoite EVs.
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Affiliation(s)
- Joshua Seun Olajide
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, 730046 China
- Centre for Distance Learning, Obafemi Awolowo University, Ile-Ife, Nigeria
| | - Ling Xiong
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, 730046 China
| | - Shunli Yang
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, 730046 China
| | - Zigang Qu
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, 730046 China
| | - Xiao Xu
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, 730046 China
| | - Bin Yang
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, 730046 China
| | - Jing Wang
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, 730046 China
| | - Baohong Liu
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, 730046 China
| | - Xueting Ma
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, 730046 China
| | - Jianping Cai
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, 730046 China
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Abstract
Apicomplexans are important pathogens that cause severe infections in humans and animals. The biology and pathogeneses of these parasites have shown that proteins are intrinsically modulated during developmental transitions, physiological processes and disease progression. Also, proteins are integral components of parasite structural elements and organelles. Among apicomplexan parasites, Eimeria species are an important disease aetiology for economically important animals wherein identification and characterisation of proteins have been long-winded. Nonetheless, this review seeks to give a comprehensive overview of constitutively expressed Eimeria proteins. These molecules are discussed across developmental stages, organelles and sub-cellular components vis-à-vis their biological functions. In addition, hindsight and suggestions are offered with intention to summarise the existing trend of eimerian protein characterisation and to provide a baseline for future studies.
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Escotte-Binet S, Huguenin A, Aubert D, Martin AP, Kaltenbach M, Florent I, Villena I. Metallopeptidases of Toxoplasma gondii: in silico identification and gene expression. ACTA ACUST UNITED AC 2018; 25:26. [PMID: 29737275 PMCID: PMC5939537 DOI: 10.1051/parasite/2018025] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 04/16/2018] [Indexed: 12/17/2022]
Abstract
Metallopeptidases are a family of proteins with domains that remain highly conserved throughout evolution. These hydrolases require divalent metal cation(s) to activate the water molecule in order to carry out their catalytic action on peptide bonds by nucleophilic attack. Metallopeptidases from parasitic protozoa, including Toxoplasma, are investigated because of their crucial role in parasite biology. In the present study, we screened the T. gondii database using PFAM motifs specific for metallopeptidases in association with the MEROPS peptidase Database (release 10.0). In all, 49 genes encoding proteins with metallopeptidase signatures were identified in the Toxoplasma genome. An Interpro Search enabled us to uncover their domain/motif organization, and orthologs with the highest similarity by BLAST were used for annotation. These 49 Toxoplasma metallopeptidases clustered into 15 families described in the MEROPS database. Experimental expression analysis of their genes in the tachyzoite stage revealed transcription for all genes studied. Further research on the role of these peptidases should increase our knowledge of basic Toxoplasma biology and provide opportunities to identify novel therapeutic targets. This type of study would also open a path towards the comparative biology of apicomplexans.
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Affiliation(s)
- Sandie Escotte-Binet
- EA 7510, ESCAPE, Laboratory of Parasitology-Mycology, University of Reims Champagne-Ardenne, 51100 Reims, France - Laboratory of Parasitology-Mycology, Toxoplasmosis National Reference Center, Toxoplasma Biological Resource Center, Maison Blanche Hospital, 51100 Reims, France
| | - Antoine Huguenin
- EA 7510, ESCAPE, Laboratory of Parasitology-Mycology, University of Reims Champagne-Ardenne, 51100 Reims, France - Laboratory of Parasitology-Mycology, Toxoplasmosis National Reference Center, Toxoplasma Biological Resource Center, Maison Blanche Hospital, 51100 Reims, France
| | - Dominique Aubert
- EA 7510, ESCAPE, Laboratory of Parasitology-Mycology, University of Reims Champagne-Ardenne, 51100 Reims, France - Laboratory of Parasitology-Mycology, Toxoplasmosis National Reference Center, Toxoplasma Biological Resource Center, Maison Blanche Hospital, 51100 Reims, France
| | - Anne-Pascaline Martin
- EA 7510, ESCAPE, Laboratory of Parasitology-Mycology, University of Reims Champagne-Ardenne, 51100 Reims, France
| | - Matthieu Kaltenbach
- EA 7510, ESCAPE, Laboratory of Parasitology-Mycology, University of Reims Champagne-Ardenne, 51100 Reims, France
| | - Isabelle Florent
- UMR7245 CNRS-MNHN, National Museum of Natural History, Department Adaptations of the Living, 75005 Paris, France
| | - Isabelle Villena
- EA 7510, ESCAPE, Laboratory of Parasitology-Mycology, University of Reims Champagne-Ardenne, 51100 Reims, France - Laboratory of Parasitology-Mycology, Toxoplasmosis National Reference Center, Toxoplasma Biological Resource Center, Maison Blanche Hospital, 51100 Reims, France
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Li SW, Lin LP, Chen SH, Fu MY, Wu GP. Purification and biochemical characterization of a puromycin-sensitive aminopeptidase from black carp muscle. Process Biochem 2015. [DOI: 10.1016/j.procbio.2015.04.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Aminopeptidase N1 (EtAPN1), an M1 metalloprotease of the apicomplexan parasite Eimeria tenella, participates in parasite development. EUKARYOTIC CELL 2014; 13:884-95. [PMID: 24839124 DOI: 10.1128/ec.00062-14] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Aminopeptidases N are metalloproteases of the M1 family that have been reported in numerous apicomplexan parasites, including Plasmodium, Toxoplasma, Cryptosporidium, and Eimeria. While investigating the potency of aminopeptidases as therapeutic targets against coccidiosis, one of the most important avian diseases caused by the genus Eimeria, we identified and characterized Eimeria tenella aminopeptidase N1 (EtAPN1). Its inhibition by bestatin and amastatin, as well as its reactivation by divalent ions, is typical of zinc-dependent metalloproteases. EtAPN1 shared a similar sequence, three-dimensional structure, and substrate specificity and similar kinetic parameters with A-M1 from Plasmodium falciparum (PfA-M1), a validated target in the treatment of malaria. EtAPN1 is synthesized as a 120-kDa precursor and cleaved into 96-, 68-, and 38-kDa forms during sporulation. Further, immunolocalization assays revealed that, similar to PfA-M1, EtAPN1 is present during the intracellular life cycle stages in both the parasite cytoplasm and the parasite nucleus. The present results support the hypothesis of a conserved role between the two aminopeptidases, and we suggest that EtAPN1 might be a valuable target for anticoccidiosis drugs.
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Katrib M, Ikin RJ, Brossier F, Robinson M, Slapetova I, Sharman PA, Walker RA, Belli SI, Tomley FM, Smith NC. Stage-specific expression of protease genes in the apicomplexan parasite, Eimeria tenella. BMC Genomics 2012; 13:685. [PMID: 23216867 PMCID: PMC3770453 DOI: 10.1186/1471-2164-13-685] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Accepted: 12/04/2012] [Indexed: 12/28/2022] Open
Abstract
Background Proteases regulate pathogenesis in apicomplexan parasites but investigations of proteases have been largely confined to the asexual stages of Plasmodium falciparum and Toxoplasma gondii. Thus, little is known about proteases in other Apicomplexa, particularly in the sexual stages. We screened the Eimeria tenella genome database for proteases, classified these into families and determined their stage specific expression. Results Over forty protease genes were identified in the E. tenella genome. These were distributed across aspartic (three genes), cysteine (sixteen), metallo (fourteen) and serine (twelve) proteases. Expression of at least fifteen protease genes was upregulated in merozoites including homologs of genes known to be important in host cell invasion, remodelling and egress in P. falciparum and/or T. gondii. Thirteen protease genes were specifically expressed or upregulated in gametocytes; five of these were in two families of serine proteases (S1 and S8) that are over-represented in the coccidian parasites, E. tenella and T. gondii, distinctive within the Apicomplexa because of their hard-walled oocysts. Serine protease inhibitors prevented processing of EtGAM56, a protein from E. tenella gametocytes that gives rise to tyrosine-rich peptides that are incorporated into the oocyst wall. Conclusion Eimeria tenella possesses a large number of protease genes. Expression of many of these genes is upregulated in asexual stages. However, expression of almost one-third of protease genes is upregulated in, or confined to gametocytes; some of these appear to be unique to the Coccidia and may play key roles in the formation of the oocyst wall, a defining feature of this group of parasites.
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Affiliation(s)
- Marilyn Katrib
- Institute for the Biotechnology of Infectious Diseases, University of Technology, Sydney, Broadway, N.S.W. 2007, Australia
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Rieux A, Gras S, Lecaille F, Niepceron A, Katrib M, Smith NC, Lalmanach G, Brossier F. Eimeripain, a cathepsin B-like cysteine protease, expressed throughout sporulation of the apicomplexan parasite Eimeria tenella. PLoS One 2012; 7:e31914. [PMID: 22457711 PMCID: PMC3310820 DOI: 10.1371/journal.pone.0031914] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Accepted: 01/17/2012] [Indexed: 11/29/2022] Open
Abstract
The invasion and replication of Eimeria tenella in the chicken intestine is responsible for avian coccidiosis, a disease that has major economic impacts on poultry industries worldwide. E. tenella is transmitted to naïve animals via shed unsporulated oocysts that need contact with air and humidity to form the infectious sporulated oocysts, which contain the first invasive form of the parasite, the sporozoite. Cysteine proteases (CPs) are major virulence factors expressed by protozoa. In this study, we show that E. tenella expresses five transcriptionally regulated genes encoding one cathepsin L, one cathepsin B and three cathepsin Cs. Biot-LC-LVG-CHN2, a cystatin derived probe, tagged eight polypeptides in unsporulated oocysts but only one in sporulated oocysts. CP-dependant activities were found against the fluorescent substrates, Z-FR-AMC and Z-LR-AMC, throughout the sporulation process. These activities corresponded to a cathepsin B-like enzyme since they were inhibited by CA-074, a specific cathepsin B inhibitor. A 3D model of the catalytic domain of the cathepsin B-like protease, based on its sequence homology with human cathepsin B, further confirmed its classification as a papain-like protease with similar characteristics to toxopain-1 from the related apicomplexan parasite, Toxoplasma gondii; we have, therefore, named the E. tenella cathepsin B, eimeripain. Following stable transfection of E. tenella sporozoites with a plasmid allowing the expression of eimeripain fused to the fluorescent protein mCherry, we demonstrated that eimeripain is detected throughout sporulation and has a punctate distribution in the bodies of extra- and intracellular parasites. Furthermore, CA-074 Me, the membrane-permeable derivative of CA-074, impairs invasion of epithelial MDBK cells by E. tenella sporozoites. This study represents the first characterization of CPs expressed by a parasite from the Eimeria genus. Moreover, it emphasizes the role of CPs in transmission and dissemination of exogenous stages of apicomplexan parasites.
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Affiliation(s)
- Anaïs Rieux
- INRA, UMR1282, Equipe Pathogenèse des Coccidioses, Infectiologie et Santé Publique, Nouzilly, France
- Université François Rabelais de Tours, UMR1282, Infectiologie et Santé Publique, Tours, France
| | - Simon Gras
- INRA, UMR1282, Equipe Pathogenèse des Coccidioses, Infectiologie et Santé Publique, Nouzilly, France
- Université François Rabelais de Tours, UMR1282, Infectiologie et Santé Publique, Tours, France
| | - Fabien Lecaille
- INSERM U618, Protéases et Vectorisation Pulmonaires, Université François Rabelais, Tours, France
| | - Alisson Niepceron
- INRA, UMR1282, Equipe Pathogenèse des Coccidioses, Infectiologie et Santé Publique, Nouzilly, France
- Université François Rabelais de Tours, UMR1282, Infectiologie et Santé Publique, Tours, France
| | - Marilyn Katrib
- Institute for the Biotechnology of Infectious Diseases, University of Technology, Sydney, Australia
| | - Nicholas C. Smith
- Queensland Tropical Health Alliance, Faculty of Medicine, Health and Molecular Sciences, James Cook University, Cairns, Australia
| | - Gilles Lalmanach
- INSERM U618, Protéases et Vectorisation Pulmonaires, Université François Rabelais, Tours, France
| | - Fabien Brossier
- INRA, UMR1282, Equipe Pathogenèse des Coccidioses, Infectiologie et Santé Publique, Nouzilly, France
- Université François Rabelais de Tours, UMR1282, Infectiologie et Santé Publique, Tours, France
- * E-mail:
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Chen X, Wu GP, Cai QF, Liu GM, Osatomi K, Su WJ, Cao MJ. Biochemical characterisation of an aminopeptidase with highest preference for lysine from Japanese flounder skeletal muscle. Food Chem 2012. [DOI: 10.1016/j.foodchem.2011.07.109] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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10
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Mucha A, Drag M, Dalton JP, Kafarski P. Metallo-aminopeptidase inhibitors. Biochimie 2010; 92:1509-29. [PMID: 20457213 PMCID: PMC7117057 DOI: 10.1016/j.biochi.2010.04.026] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Accepted: 04/29/2010] [Indexed: 01/05/2023]
Abstract
Aminopeptidases are enzymes that selectively hydrolyze an amino acid residue from the N-terminus of proteins and peptides. They are important for the proper functioning of prokaryotic and eukaryotic cells, but very often are central players in the devastating human diseases like cancer, malaria and diabetes. The largest aminopeptidase group include enzymes containing metal ion(s) in their active centers, which often determines the type of inhibitors that are the most suitable for them. Effective ligands mostly bind in a non-covalent mode by forming complexes with the metal ion(s). Here, we present several approaches for the design of inhibitors for metallo-aminopeptidases. The optimized structures should be considered as potential leads in the drug discovery process against endogenous and infectious diseases.
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Affiliation(s)
- Artur Mucha
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland.
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Rudenskaya YA, Aseev VV, Rudenskaya GN. Endocellular aminopeptidase from Astasia longa. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2008. [DOI: 10.1134/s1068162008030084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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12
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Fetterer RH, Miska KB, Lillehoj H, Barfield RC. Serine protease activity in developmental stages of Eimeria tenella. J Parasitol 2007; 93:333-40. [PMID: 17539417 DOI: 10.1645/ge-824r1.1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
A number of complex processes are involved in Eimeria spp. survival, including control of sporulation, intracellular invasion, evasion of host immune responses, successful reproduction, and nutrition. Proteases have been implicated in many of these processes, but the occurrence and functions of serine proteases have not been characterized. Bioinformatic analysis suggests that the Eimeria tenella genome contains several serine proteases that lack homology to trypsin. Using RT-PCR, a gene encoding a subtilisin-like and a rhomboid protease-like serine protease was shown to be developmentally regulated, both being poorly expressed in sporozoites (SZ) and merozoites (MZ). Casein substrate gel electrophoresis of oocyst extracts during sporulation demonstrated bands of proteolytic activity with relative molecular weights (Mr) of 18, 25, and 45 kDa that were eliminated by coincubation with serine protease inhibitors. A protease with Mr of 25 kDa was purified from extracts of unsporulated oocysts by a combination of affinity and anion exchange chromatography. Extracts of SZ contained only a single band of inhibitor-sensitive proteolytic activity at 25 kDa, while the pattern of proteases from extracts of MZ was similar to that of oocysts except for the occurrence of a 90 kDa protease, resistant to protease inhibitors. Excretory-secretory products (ESP) from MZ contained AEBSF (4-[2-Aminoethyl] benzenesulphonyl fluoride)-sensitive protease activity with a specific activity about 10 times greater than that observed in MZ extracts. No protease activity was observed in the ESP from SZ. Pretreatment of SZ with AEBSF significantly reduced SZ invasion and the release of the microneme protein, MIC2. The current results suggest that serine proteases are present in all the developmental stages examined.
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Affiliation(s)
- R H Fetterer
- Animal Parasitic Diseases Laboratory, Animal and Natural Resources institute, United States Department of Agriculture, Henry A. Wallace Beltsville Agricultural Research Center, Beltsville, Maryland 20705, USA.
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