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Prolyl aminopeptidases: Reclassification, properties, production and industrial applications. Process Biochem 2022. [DOI: 10.1016/j.procbio.2022.04.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Biochemical Characterisation and Structure Determination of a Novel Cold-Active Proline Iminopeptidase from the Psychrophilic Yeast, Glaciozyma antarctica PI12. Catalysts 2022. [DOI: 10.3390/catal12070722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Microbial proteases constitute one of the most important groups of industrially relevant enzymes. Proline iminopeptidases (PIPs) that specifically release amino-terminal proline from peptides are of major interest for applications in food biotechnology. Proline iminopeptidase has been extensively characterised in bacteria and filamentous fungi. However, no similar reports exist for yeasts. In this study, a protease gene from Glaciozyma antarctica designated as GaPIP was cloned and overexpressed in Escherichia coli. Sequence analyses of the gene revealed a 960 bp open reading frame encoding a 319 amino acid protein (35,406 Da). The purified recombinant GaPIP showed a specific activity of 3561 Umg−1 towards L-proline-p-nitroanilide, confirming its identity as a proline iminopeptidase. GaPIP is a cold-active enzyme with an optimum activity of 30 °C at pH 7.0. The enzyme is stable between pH 7.0 and 8.0 and able to retain its activity at 10–30 °C. Although GaPIP is a serine protease, only 25% inhibition by the serine protease inhibitor, phenylmethanesulfonylfluoride (PMSF) was recorded. This enzyme is strongly inhibited by the presence of EDTA, suggesting that it is a metalloenzyme. The dimeric structure of GaPIP was determined at a resolution of 2.4 Å. To date, GaPIP is the first characterised PIP from yeasts and the structure of GaPIP is the first structure for PIP from eukaryotes.
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Ghifari AS, Teixeira PF, Kmiec B, Pružinská A, Glaser E, Murcha MW. A mitochondrial prolyl aminopeptidase PAP2 releases N-terminal proline and regulates proline homeostasis during stress response. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 104:1182-1194. [PMID: 32920905 DOI: 10.1111/tpj.14987] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 08/17/2020] [Accepted: 08/19/2020] [Indexed: 06/11/2023]
Abstract
Most mitochondrial proteins are synthesised in the cytosol and targeted into the organelle via N-terminal targeting peptides that are cleaved upon import. The free targeting peptide is subsequently processed in a stepwise manner, with single amino acids released as final products. Here, we have characterised a proline-cleaving aminopeptidase in Arabidopsis thaliana, prolyl aminopeptidase-2 (PAP2, At3g61540). Activity assays show that PAP2 has a preferred activity to hydrolyse N-terminal proline. Protein localisation studies revealed that PAP2 is exclusively targeted to mitochondria. Characterisation of pap2 mutants show defective pollen, enhanced dark-induced senescence and increased susceptibility to abiotic stresses, which are likely attributed to a reduced level of accumulated free proline. Taken together, these results demonstrate the role of PAP2 in proline cleavage from mitochondrial peptides and proline homeostasis, which is required for the development of male gametophyte, tolerance to abiotic stresses, and leaf senescence.
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Affiliation(s)
- Abi S Ghifari
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA, 6009, Australia
- ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA, 6009, Australia
| | - Pedro F Teixeira
- Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, Stockholm, SE-106 91, Sweden
| | - Beata Kmiec
- Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, Stockholm, SE-106 91, Sweden
| | - Adriana Pružinská
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA, 6009, Australia
- ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA, 6009, Australia
| | - Elzbieta Glaser
- Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, Stockholm, SE-106 91, Sweden
| | - Monika W Murcha
- School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA, 6009, Australia
- ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA, 6009, Australia
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Liu D, Zhang D, Huang Q, Gu L, Zhou N, Tian Y. Mutagenesis for Improvement of Activity and Stability of Prolyl Aminopeptidase from Aspergillus oryzae. Appl Biochem Biotechnol 2020; 191:1483-1498. [PMID: 32125650 DOI: 10.1007/s12010-020-03277-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 02/13/2020] [Indexed: 11/27/2022]
Abstract
In this study, the prokaryotic expression system of Escherichia coli was used to modify prolyl aminopeptidase derived from Aspergillus oryzae JN-412 (AoPAP) via random mutagenesis and site-directed saturation mutagenesis. A random mutant library with a capacity of approximately 3000 mutants was compiled using error-prone polymerase chain reaction, and nonconservative amino acids within 3 Å of the substrate L-proline-p-nitroaniline were selected as site-directed saturation mutagenesis sites via homologous simulation and molecular docking of AoPAP. Variants featuring high catalytic efficiency were screened by a high-throughput screening method. The specific activities of the variants of 3D9, C185V, and Y393W were 127 U mg-1, 156 U mg-1, and 120 U mg-1, respectively, which were 27%, 56%, and 20% higher than those of the wild type, with a value of 100 U mg-1. The half-life of thermostability of the mutant 3D9 was 4.5 h longer than that of the wild type at 50 °C. The mutant C185V improved thermostability and had a half-life 2 h longer than that of the wild type at a pH of 6.5. Prolyl aminopeptidase had improved stability within the acidic range and thermostability after modification, making it more suitable for a synergistic combination with various acidic and neutral endoproteases.
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Affiliation(s)
- Dehua Liu
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Dawei Zhang
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Qinqin Huang
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Lili Gu
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China
| | - Nandi Zhou
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China.
| | - Yaping Tian
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China.
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Wang K, Tian Y, Zhou N, Liu D, Zhang D. Studies on fermentation optimization, stability and application of prolyl aminopeptidase from Bacillus subtilis. Process Biochem 2018. [DOI: 10.1016/j.procbio.2018.08.035] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Chanalia P, Gandhi D, Attri P, Dhanda S. Extraction, purification and characterization of low molecular weight Proline iminopeptidase from probiotic L. plantarum for meat tenderization. Int J Biol Macromol 2018; 109:651-663. [DOI: 10.1016/j.ijbiomac.2017.12.092] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 10/26/2017] [Accepted: 12/17/2017] [Indexed: 10/18/2022]
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Nandan A, Nampoothiri KM. Molecular advances in microbial aminopeptidases. BIORESOURCE TECHNOLOGY 2017; 245:1757-1765. [PMID: 28599921 DOI: 10.1016/j.biortech.2017.05.103] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 05/15/2017] [Accepted: 05/16/2017] [Indexed: 05/22/2023]
Abstract
Aminopeptidases are exopeptidases that catalyze the hydrolysis of amino acid residues from the N terminus of peptides and proteins. They are widely and diversely used for protein hydrolysis in industrial and research applications. They form a large enzyme family in microorganisms and most of the sequenced microbial genomes contain several aminopeptidase coding genes. Various approaches are being used to enhance the yield and desired properties of these enzymes to make it more suited for industrial applications. Novel aminopeptidases are being developed by site directed mutagenesis and recombinant DNA technology with improved substrate specificity and stability. This review focuses on its classification and recent advancements in the molecular studies pertaining to this enzyme.
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Affiliation(s)
- Arya Nandan
- CSIR-National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum 695019, Kerala, India
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Zdunek-Zastocka E, Grabowska A, Branicki T, Michniewska B. Biochemical characterization of the triticale TsPAP1, a new type of plant prolyl aminopeptidase, and its impact on proline content and flowering time in transgenic Arabidopsis plants. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2017; 116:18-26. [PMID: 28482331 DOI: 10.1016/j.plaphy.2017.04.026] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 04/20/2017] [Accepted: 04/26/2017] [Indexed: 06/07/2023]
Abstract
Proline aminopeptidase (PAP, EC 3.4.11.5) is the only enzyme that effectively releases proline from the N-termini of peptides. The amino acid sequence of the PAP from Triticosecale, TsPAP1, comprises conserved regions, characteristic of the monomeric forms of PAP found in bacteria but not yet identified in plants. Therefore, we aimed to obtain and biochemically characterize the TsPAP1 protein. The recombinant TsPAP1 protein was received through heterologous expression of the TsPAP1 coding sequence in a bacterial expression system and purified with affinity chromatography. Gel filtration chromatography and SDS electrophoresis revealed that TsPAP1 is a monomer with a molecular mass of 37.5 kDa. TsPAP1 prefers substrates with proline at the N-terminus but is also capable of hydrolyzing β-naphthylamides of hydroxyproline and alanine. Among the peptides tested, the most preferred were di- and tripeptides, especially those with glycine in the Y position. The use of diagnostic inhibitors indicated that TsPAP1 is a serine peptidase; however, further characterization revealed that the SH residues are also important for maintaining its activity. To examine the role of TsPAP1 under physiological conditions, we developed transgenic Arabidopsis plants overexpressing TsPAP1. Compared with wild-type plants, the transgenic lines accumulated more proline, flowered an average of 3.5 days earlier, and developed more siliques than did untransformed controls. Our paper is the first to describe the biochemical properties of a novel monomeric plant PAP and contributes to the functional characterization of PAP proteins in plants.
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Affiliation(s)
- Edyta Zdunek-Zastocka
- Department of Biochemistry, Warsaw University of Life Sciences - SGGW, Nowoursynowska 159, 02-776 Warsaw, Poland.
| | - Agnieszka Grabowska
- Department of Biochemistry, Warsaw University of Life Sciences - SGGW, Nowoursynowska 159, 02-776 Warsaw, Poland
| | - Tomasz Branicki
- Department of Biochemistry, Warsaw University of Life Sciences - SGGW, Nowoursynowska 159, 02-776 Warsaw, Poland
| | - Beata Michniewska
- Department of Biochemistry, Warsaw University of Life Sciences - SGGW, Nowoursynowska 159, 02-776 Warsaw, Poland
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Wang KD, Wang KH, Zhou ND, Tian YP. Secretory Expression, Purification, Characterization, and Application of an Aspergillus oryzae Prolyl Aminopeptidase in Bacillus subtilis. Appl Biochem Biotechnol 2016; 181:1611-1623. [DOI: 10.1007/s12010-016-2305-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 10/24/2016] [Indexed: 01/26/2023]
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Prolyl-specific peptidases for applications in food protein hydrolysis. Appl Microbiol Biotechnol 2015; 99:7837-46. [DOI: 10.1007/s00253-015-6838-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 07/08/2015] [Accepted: 07/11/2015] [Indexed: 01/20/2023]
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Jing Z, Feng H. Studies on the molecular docking and amino Acid residues involving in recognition of substrate in proline iminopeptidase by site-directed mutagenesis. Protein J 2015; 34:173-80. [PMID: 25957260 DOI: 10.1007/s10930-015-9611-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/04/2015] [Indexed: 11/29/2022]
Abstract
The proline iminopeptidase (PchPiPA) of Phanerochaete chrysosporium catalyze specifically hydrolysis of N-terminal proline from peptides. The substrate Pro-pNA was docked into the catalytic pocket and several amino acid residues were identified to interact or associate with the substrate. Eight residues were selected for site-directed mutagenesis. The wild-type and mutant proteins were expressed in Escherichia coli and purified. Kinetic parameters were calculated by hydrolyzing Pro-pNA for these enzymes. Substitution of two Glu residues (Glu198 and Glu227) which interact with the substrate via formation of hydrogen bond, led to deleterious effect on catalytic efficiency (k(cat)/K(m)) due to decrease of k(cat) and increase of K(m). Four Phe residues consisting of catalytic pocket and surrounding the docked substrate, were substituted with Ala, resulting in decrease in k(cat)/K(m) to various extents. Substitution of two residues (Val267 and Cys267) localized at the deep end of the catalytic pocket also yielded negative influence on the substrate hydrolysis. Besides, all the mutants except E227Q exhibited lower thermostability than the wild-type did, indicating that these mutations may modulate the local structure. In conclusion, these amino acid residues may play an important role in maintaining local environment of the impacted catalytic pocket and be involved in recognizing or positioning the substrate.
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Affiliation(s)
- Zhixin Jing
- The Key Laboratory for Biological Resources and the Environment of Ministry of Education, The Sichuan Key Laboratory of Molecular Biology and Biotechnology, College of Life Sciences, Sichuan University, Chengdu, 610064, Sichuan, People's Republic of China
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Zelena K, Eisele N, Berger RG. Escherichia coli as a production host for novel enzymes from basidiomycota. Biotechnol Adv 2014; 32:1382-95. [DOI: 10.1016/j.biotechadv.2014.08.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 08/14/2014] [Accepted: 08/25/2014] [Indexed: 01/14/2023]
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13
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Jiménez DJ, Dini-Andreote F, Ottoni JR, de Oliveira VM, van Elsas JD, Andreote FD. Compositional profile of α / β-hydrolase fold proteins in mangrove soil metagenomes: prevalence of epoxide hydrolases and haloalkane dehalogenases in oil-contaminated sites. Microb Biotechnol 2014; 8:604-13. [PMID: 25171437 PMCID: PMC4408192 DOI: 10.1111/1751-7915.12157] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 07/22/2014] [Accepted: 07/24/2014] [Indexed: 11/30/2022] Open
Abstract
The occurrence of genes encoding biotechnologically relevant α/β-hydrolases in mangrove soil microbial communities was assessed using data obtained by whole-metagenome sequencing of four mangroves areas, denoted BrMgv01 to BrMgv04, in São Paulo, Brazil. The sequences (215 Mb in total) were filtered based on local amino acid alignments against the Lipase Engineering Database. In total, 5923 unassembled sequences were affiliated with 30 different α/β-hydrolase fold superfamilies. The most abundant predicted proteins encompassed cytosolic hydrolases (abH08; ∼ 23%), microsomal hydrolases (abH09; ∼ 12%) and Moraxella lipase-like proteins (abH04 and abH01; < 5%). Detailed analysis of the genes predicted to encode proteins of the abH08 superfamily revealed a high proportion related to epoxide hydrolases and haloalkane dehalogenases in polluted mangroves BrMgv01-02-03. This suggested selection and putative involvement in local degradation/detoxification of the pollutants. Seven sequences that were annotated as genes for putative epoxide hydrolases and five for putative haloalkane dehalogenases were found in a fosmid library generated from BrMgv02 DNA. The latter enzymes were predicted to belong to Actinobacteria, Deinococcus-Thermus, Planctomycetes and Proteobacteria. Our integrated approach thus identified 12 genes (complete and/or partial) that may encode hitherto undescribed enzymes. The low amino acid identity (< 60%) with already-described genes opens perspectives for both production in an expression host and genetic screening of metagenomes.
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Affiliation(s)
- Diego Javier Jiménez
- Department of Microbial Ecology, Centre for Ecological and Evolutionary Studies, University of Groningen, Groningen, 9747AG, The Netherlands
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Ding GW, Zhou ND, Tian YP. Over-Expression of a Proline Specific Aminopeptidase from Aspergillus oryzae JN-412 and Its Application in Collagen Degradation. Appl Biochem Biotechnol 2014; 173:1765-77. [DOI: 10.1007/s12010-014-0963-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2014] [Accepted: 05/15/2014] [Indexed: 10/25/2022]
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Xing K, Feng H. Role of amino acid residues involved in the active cavity of proline iminopeptidase in catalytic activity. ACTA ACUST UNITED AC 2013. [DOI: 10.4236/abc.2013.33032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Szawłowska U, Grabowska A, Zdunek-Zastocka E, Bielawski W. TsPAP1 encodes a novel plant prolyl aminopeptidase whose expression is induced in response to suboptimal growth conditions. Biochem Biophys Res Commun 2012; 419:104-9. [DOI: 10.1016/j.bbrc.2012.01.140] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 01/28/2012] [Indexed: 10/14/2022]
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Szawłowska U, Zdunek-Zastocka E, Bielawski W. Biochemical characterisation of prolyl aminopeptidase from shoots of triticale seedlings and its activity changes in response to suboptimal growth conditions. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2011; 49:1342-1349. [PMID: 21689943 DOI: 10.1016/j.plaphy.2011.05.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Accepted: 05/17/2011] [Indexed: 05/30/2023]
Abstract
Prolyl aminopeptidase (PAP) was isolated from the shoots of three-day-old triticale seedlings and was purified using a five-step purification procedure (acid precipitation, gel filtration, anion-exchange chromatography, hydrophobic chromatography and rechromatography). The enzyme was purified 460-fold with a recovery of 6%. Prolyl aminopeptidase appears to be a tetramer consisting of four subunits, each with a molecular weight of approximately 54kDa. Its pH and temperature optimum are pH 7.5 and 37°C, respectively. The enzyme prefers substrates with Pro and Hyp at the N-terminus, but is also capable of hydrolysing β-naphthylamides (β-NA) of Ala, Phe, and Leu. The K(m) value of PAP against Pro-β-NA was the lowest among the substrates tested and it was 1.47×10(-5)M. The activity of PAP was not inhibited by EDTA, 1,10-phenantroline, or pepstatin A. The most effective inhibitors were DFP, Pefabloc, and PMSF, which are serine protease inhibitors. However, significant inhibition was also observed in the presence of E-64, which modifies sulfhydryl groups. A significant increase of the aminopeptidase activity against Pro-β-NA was observed in shoots of triticale plants grown under salinity, drought stress, and in the presence of cadmium and aluminium ions in the nutrient solution.
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Affiliation(s)
- Urszula Szawłowska
- Department of Biochemistry, Warsaw University of Life Sciences - SGGW, Nowoursynowska 159, 02-776 Warsaw, Poland
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Tchorbanov B, Marinova M, Grozeva L. Debittering of Protein Hydrolysates by Lactobacillus LBL-4 Aminopeptidase. Enzyme Res 2011; 2011:538676. [PMID: 21876793 PMCID: PMC3162980 DOI: 10.4061/2011/538676] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 06/28/2011] [Accepted: 06/30/2011] [Indexed: 11/25/2022] Open
Abstract
Yoghurt strain Lactobacillus LBL-4 cultivated for 8–10 h at pH ~6.0 was investigated as a considerable food-grade source of intracellular aminopeptidase. Cell-free extract manifesting >200 AP U/l was obtained from cells harvested from 1 L culture media. Subtilisin-induced hydrolysates of casein, soybean isolate, and Scenedesmus cell protein with degree of hydrolysis 20–22% incubated at 45°C for 10 h by 10 AP U/g peptides caused an enlarging of DH up to 40–42%, 46–48%, and 38–40% respectively. The DH increased rapidly during the first 4 h, but gel chromatography studies on BioGel P-2 showed significant changes occurred during 4–10 h of enzyme action when the DH increased gradually. After the digestion, the remained AP activity can be recovered by ultrafiltration (yield 40–50%). Scenedesmus protein hydrolysate with DH 20% was inoculated by Lactobacillus LBL-4 cells, and after 72 h cultivation the DH reached 32%. The protein hydrolysates (DH above 40%) obtained from casein and soybean isolate (high Q value) demonstrated a negligible bitterness while Scenedesmus protein hydrolysates (low Q value) after both treatments were free of bitterness.
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Affiliation(s)
- Bozhidar Tchorbanov
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str. 9, 1113 Sofia, Bulgaria
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