Littérature scientifique sur le sujet « Dsz enzymes »
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Articles de revues sur le sujet "Dsz enzymes"
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Li, Guo-qiang, Shan-shan Li, Ming-lu Zhang, Jun Wang, Lin Zhu, Feng-lai Liang, Ru-lin Liu et Ting Ma. « Genetic Rearrangement Strategy for Optimizing the Dibenzothiophene Biodesulfurization Pathway in Rhodococcus erythropolis ». Applied and Environmental Microbiology 74, no 4 (28 décembre 2007) : 971–76. http://dx.doi.org/10.1128/aem.02319-07.
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ABSTRACT Dibenzothiophene (DBT) and its derivatives can be microbially desulfurized by enzymes DszC, DszA, and DszB, which are encoded by the operon dszABC and contribute to the conversion in tandem. We investigated the expression characteristics of the dsz operon. Our results revealed that the levels of transcription and translation of dszA, dszB, and dszC decreased according to the positions of the genes in the dsz operon. Furthermore, the translation of dszB was repressed by an overlapping structure in the dsz operon. In order to get better and steady expression of the Dsz enzymes and optimize the metabolic flux of DBT, we rearranged the dsz operon according to the catalytic capabilities of the Dsz enzymes and expressed the rearranged dsz operon, dszBCA, in Rhodococcus erythropolis. After rearrangement, the ratio of dszA, dszB, and dszC mRNAs in the cells was changed, from 11:3.3:1 to 1:16:5. Western blot analysis revealed that the levels of expression of dszB and dszC had been enhanced but that the expression of dszA had decreased. The desulfurization activity of resting cells prepared from R. erythropolis DRB, which carried the rearranged dsz operon, was about 12-fold higher than that of resting cells of R. erythropolis DRA, which carried the original operon in a similarly constructed vector.
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Sousa, João P. M., Pedro Ferreira, Rui P. P. Neves, Maria J. Ramos et Pedro A. Fernandes. « The bacterial 4S pathway – an economical alternative for crude oil desulphurization that reduces CO2 emissions ». Green Chemistry 22, no 22 (2020) : 7604–21. http://dx.doi.org/10.1039/d0gc02055a.
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We discuss structural and mechanistic aspects of the Dsz enzymes in the 4S pathway, with a focus on rational molecular strategies for enzyme engineering, aiming at enzyme catalytic rate and efficiency improvement to meet industrial demands.
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Pan, Jie, Fan Wu, Jia Wang, Linqing Yu, Naghmeh Hassanzadeh Khayyat, Benjamin C. Stark et John J. Kilbane. « Enhancement of desulfurization activity by enzymes of the Rhodococcus dsz operon through coexpression of a high sulfur peptide and directed evolution ». Fuel 112 (octobre 2013) : 385–90. http://dx.doi.org/10.1016/j.fuel.2013.04.065.
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Tanaka, Yasuhiro, Osamu Yoshikawa, Kenji Maruhashi et Ryuichiro Kurane. « The cbs mutant strain of Rhodococcus erythropolis KA2-5-1 expresses high levels of Dsz enzymes in the presence of sulfate ». Archives of Microbiology 178, no 5 (1 novembre 2002) : 351–57. http://dx.doi.org/10.1007/s00203-002-0466-7.
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Li, Lu, Lei Ye, Zhijie Guo, Wei Zhang, Xihao Liao, Ying Lin et Shuli Liang. « A kinetic model to optimize and direct the dose ratio of Dsz enzymes in the 4S desulfurization pathway in vitro and in vivo ». Biotechnology Letters 41, no 11 (14 septembre 2019) : 1333–41. http://dx.doi.org/10.1007/s10529-019-02730-1.
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Duarte, Gabriela Frois, Alexandre Soares Rosado, Lucy Seldin, Welington de Araujo et Jan Dirk van Elsas. « Analysis of Bacterial Community Structure in Sulfurous-Oil-Containing Soils and Detection of Species Carrying Dibenzothiophene Desulfurization (dsz) Genes ». Applied and Environmental Microbiology 67, no 3 (1 mars 2001) : 1052–62. http://dx.doi.org/10.1128/aem.67.3.1052-1062.2001.
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ABSTRACT The selective effects of sulfur-containing hydrocarbons, with respect to changes in bacterial community structure and selection of desulfurizing organisms and genes, were studied in soil. Samples taken from a polluted field soil (A) along a concentration gradient of sulfurous oil and from soil microcosms treated with dibenzothiophene (DBT)-containing petroleum (FSL soil) were analyzed. Analyses included plate counts of total bacteria and of DBT utilizers, molecular community profiling via soil DNA-based PCR-denaturing gradient gel electrophoresis (PCR-DGGE), and detection of genes that encode enzymes involved in the desulfurization of hydrocarbons, i.e., dszA, dszB, and dszC.Data obtained from the A soil showed no discriminating effects of oil levels on the culturable bacterial numbers on either medium used. Generally, counts of DBT degraders were 10- to 100-fold lower than the total culturable counts. However, PCR-DGGE showed that the numbers of bands detected in the molecular community profiles decreased with increasing oil content of the soil. Analysis of the sequences of three prominent bands of the profiles generated with the highly polluted soil samples suggested that the underlying organisms were related to Actinomyces sp.,Arthrobacter sp., and a bacterium of uncertain affiliation.dszA, dszB, and dszC genes were present in all A soil samples, whereas a range of unpolluted soils gave negative results in this analysis. Results from the study of FSL soil revealed minor effects of the petroleum-DBT treatment on culturable bacterial numbers and clear effects on the DBT-utilizing communities. The molecular community profiles were largely stable over time in the untreated soil, whereas they showed a progressive change over time following treatment with DBT-containing petroleum. Direct PCR assessment revealed the presence of dszB-related signals in the untreated FSL soil and the apparent selection of dszA- and dszC-related sequences by the petroleum-DBT treatment. PCR-DGGE applied to sequential enrichment cultures in DBT-containing sulfur-free basal salts medium prepared from the A and treated FSL soils revealed the selection of up to 10 distinct bands. Sequencing a subset of these bands provided evidence for the presence of organisms related to Pseudomonas putida, a Pseudomonassp., Stenotrophomonas maltophilia, and Rhodococcus erythropolis. Several of 52 colonies obtained from the A and FSL soils on agar plates with DBT as the sole sulfur source produced bands that matched the migration of bands selected in the enrichment cultures. Evidence for the presence of dszB in 12 strains was obtained, whereas dszA and dszC genes were found in only 7 and 6 strains, respectively. Most of the strains carrying dszA or dszC were classified asR. erythropolis related, and all revealed the capacity to desulfurize DBT. A comparison of 37 dszA sequences, obtained via PCR from the A and FSL soils, from enrichments of these soils, and from isolates, revealed the great similarity of all sequences to the canonical (R. erythropolis strain IGTS8)dszA sequence and a large degree of internal conservation. The 37 sequences recovered were grouped in three clusters. One group, consisting of 30 sequences, was minimally 98% related to the IGTS8 sequence, a second group of 2 sequences was slightly different, and a third group of 5 sequences was 95% similar. The first two groups contained sequences obtained from both soil types and enrichment cultures (including isolates), but the last consisted of sequences obtained directly from the polluted A soil.
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Pan, Jie, Fan Wu, Jia Wang, Linqing Yu, Naghmeh Hassanzadeh Khayyat, Benjamin C. Stark et John J. Kilbane II. « Corrigendum to “Enhancement of desulfurization activity by enzymes of the Rhodococcus dsz operon through coexpression of a high sulfur peptide and directed evolution” [Fuel 112 (2013) 385–390] ». Fuel 113 (novembre 2013) : 766. http://dx.doi.org/10.1016/j.fuel.2013.07.061.
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Elnashar, Magdy M. M., et Mohamed E. Hassan. « Novel Epoxy Activated Hydrogels for Solving Lactose Intolerance ». BioMed Research International 2014 (2014) : 1–9. http://dx.doi.org/10.1155/2014/817985.
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“Lactose intolerance” is a medical problem for almost 70% of the world population. Milk and dairy products contain 5–10% w/v lactose. Hydrolysis of lactose by immobilized lactase is an industrial solution. In this work, we succeeded to increase the lactase loading capacity to more than 3-fold to 36.3 U/g gel using epoxy activated hydrogels compared to 11 U/g gel using aldehyde activated carrageenan. The hydrogel’s mode of interaction was proven by FTIR, DSC, and TGA. The high activity of the epoxy group was regarded to its ability to attach to the enzyme’s –SH, –NH, and –OH groups, whereas the aldehyde group could only bind to the enzyme’s –NH2group. The optimum conditions for immobilization such as epoxy chain length and enzyme concentration have been studied. Furthermore, the optimum enzyme conditions were also deliberated and showed better stability for the immobilized enzyme and the Michaelis constants,KmandVmax, were doubled. Results revealed also that both free and immobilized enzymes reached their maximum rate of lactose conversion after 2 h, albeit, the aldehyde activated hydrogel could only reach 63% of the free enzyme. In brief, the epoxy activated hydrogels are more efficient in immobilizing more enzymes than the aldehyde activated hydrogel.
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Akhir, J., S. W. Budi, E. N. Herliyana et Surono. « Lignocellulolytic enzyme potential of dark septate endophyte (dse) from Pinus merkusii roots in Dramaga Bogor Indonesia ». IOP Conference Series : Earth and Environmental Science 959, no 1 (1 janvier 2022) : 012031. http://dx.doi.org/10.1088/1755-1315/959/1/012031.
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Abstract The ability of Dark Septate Endophyte (DSE) derived from the roots of P. merkusii in decomposing organic matter is not much published. This study aims to determine the activity of lignolytic and cellulolytic enzymes, as well as the value of the cellulolytic index of Apls, isolates from P. merkusii roots taken from IPB Dramaga Bogor. Enzyme activity was tested by measuring the clear zone formed, while the cellulolytic index value was obtained by measuring the ratio of the clear zone formed around the colony. Data were analyzed descriptively. The results identified 10 isolates, 8 Apls isolates had potential enzyme activity that able to form clear zone, 5 isolates had lignolytic enzyme activity (Apls 1.4.1, Apls 2.3.1.1, Apls 3.4.2, Apls 2.1.1 and Apls 3.4 1.1) and 1 isolate had cellulolytic enzyme activity (Apls 3.1.3), and 2 isolates had lignocellulolytic enzyme activity (Apls 1.5.3 and Apls 3.4.3b), with the highest cellulolytic index value in Apls 1.5.3 isolates of 0,87 mm. 2 isolates had not lignocellulolytic enzymes activity (Apls 3.4.3 and Apls 3.1.4). The DSE roots of P. merkusii from IPB Dramaga Bogor had the potential for lignocellulolytic enzymes of 20 per cent of the total DSE found.
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Kloosterman, H., G. I. Hessels, J. W. Vrijbloed, G. J. Euverink et L. Dijkhuizen. « (De)regulation of key enzyme steps in the shikimate pathway and phenylalanine-specific pathway of the actinomycete Amycolatopsis methanolica ». Microbiology 149, no 11 (1 novembre 2003) : 3321–30. http://dx.doi.org/10.1099/mic.0.26494-0.
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Prephenate dehydratase (PDT), chorismate mutase (CM) and 3-deoxy-d-arabino-7-heptulosonate 7-phosphate (DAHP) synthase are key regulatory enzymes in aromatic amino acid biosynthesis in the actinomycete Amycolatopsis methanolica. Deregulated, feedback-control-resistant mutants were isolated by incubation of A. methanolica on glucose mineral agar containing the toxic analogue p-fluoro-dl-phenylalanine (pFPhe). Several of these mutants had completely lost PDT sensitivity to Phe inhibition and Tyr activation. Mutant characterization yielded new information about PDT amino acid residues involved in Phe and Tyr effector binding sites. A. methanolica wild-type cells grown on glucose mineral medium normally possess a bifunctional CM/DAHP synthase protein complex (with DS1, a plant-type DAHP synthase). The CM activity of this protein complex is feedback-inhibited by Tyr and Phe, while DS1 activity is mainly inhibited by Trp. Isolation of pFPhe-resistant mutants yielded two feedback-inhibition-resistant CM mutants. These were characterized as regulatory mutants, derepressed in (a) synthesis of CM, now occurring as an abundant, feedback-inhibition-resistant, separate protein, and (b) synthesis of an alternative DAHP synthase (DS2, an E. coli-type DAHP synthase), only inhibited by Tyr and Trp. DS1 and DS2 thus are well integrated in A. methanolica primary metabolism: DS1 and CM form a protein complex, which stimulates CM activity and renders it sensitive to feedback inhibition by Phe and Tyr. Synthesis of CM and DS2 proteins appears to be controlled co-ordinately, sensitive to Phe-mediated feedback repression.
Thèses sur le sujet "Dsz enzymes"
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PARRAVICINI, FEDERICA. « Characterization of enzymes from desulfurizing bacterial strains ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2015. http://hdl.handle.net/10281/76247.
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L’enorme quantità di pneumatici fuori uso accumulati costituisce un grave problema ambientale. Per porvi rimedio si cercano soluzioni che mirano al riutilizzo della gomma naturale (NR), principale materia prima utilizzata nella produzione di pneumatici.
Per poter essere riutilizzata, la NR viene generalmente macinata finemente e sottoposta ad un trattamento di devulcanizzazione, cioè alla rottura dei ponti trasversali zolfo-zolfo.
Diversi metodi chimici o meccanici sono utilizzabili per devulcanizzare il polverino. Tuttavia, ciascuno di essi presenta degli svantaggi. Sarebbe quindi auspicabile la messa a punto di processi in cui reazioni specifiche siano realizzate in condizioni moderate di temperatura e pressione. In questo scenario l’utilizzo di biocatalizzatori potrebbe costituire un’alternativa valida e di minor impatto ambientale.
Questo studio si occupa di verificare la possibilità di trattamenti enzimatici di “biodevulcanizzazione”.
Non essendo noti enzimi in grado di devulcanizzare la gomma, questo lavoro di tesi è partito dall’analisi di microrganismi isolati da campioni ambientali e con potenziali proprietà desolforanti che sono state saggiate su un substrato modello, il dibenzotiofene (DBT).
Il primo screening sui microrganismi ha portato alla selezione di un nuovo ceppo di Rhodococcus sp. AF21875. L’attività desolforante di questo microrganismo è stata studiata con due approcci paralleli, da un lato verificando la presenza di geni codificanti per enzimi che desolforano il DBT e dall’altro individuando nuovi enzimi con abilità desolforanti.
In batteri attivi in processi di desolforazione, i geni dsz codificano per 4 enzimi: DszA, DszB, DszC e DszD. Nel DNA genomico di Rhodococcus sp. AF21875 è stata verificata la presenza dei quattro geni dsz, che sono stati clonati per consentire la produzione ricombinante delle proteine corrispondenti in un ceppo del batterio Escherichia coli. Tre delle proteine, DszA, DszC e DszD, sono abbondantemente espresse in forma solubile e sono state purificate con successo. In previsione di un impiego biotecnologico delle proteine DszA, DszC e DszD è stata intrapresa l’analisi di alcune caratteristiche strutturali e di stabilità. In particolare, è stata analizzata la composizione della struttura secondaria e la stabilità al calore mediante dicroismo circolare; la stabilità in presenza di diversi solventi organici, attraverso spettrofluorimetria.
L’attività degli enzimi è stata monitorata mediante cromatografia liquida (HPLC) che consente di rilevare la formazione di 2-idrossibifenile (HBP) come prodotto finale di reazione. L’attività di desolforazione dei quattro enzimi è stata infine saggiata su gomma naturale vulcanizzata. È emerso che il trattamento enzimatico provoca modificazioni chimiche della gomma. Sebbene le analisi condotte evidenzino cambiamenti di modesta entità e non associabili univocamente ad un processo di desolforazione, gli enzimi individuati costituiscono un buon punto di partenza per approcci di ingegneria proteica volti a migliorare l’attività e la stabilità degli enzimi Dsz da Rhodococcus sp. AF21875.
Inoltre, per individuare nuove attività enzimatiche è stata eseguita un’analisi di proteomica differenziale delle cellule di Rhodococcus sp. AF21875. Da cellule cresciute in terreno privo o addizionato di DBT sono state estratte le proteine totali che sono state analizzate mediante elettroforesi bidimensionale. Quando Rhodococcus sp. AF21875 cresce in presenza di DBT, produce un pool di proteine che non si ritrovano tra le proteine espresse in assenza di DBT. Tre delle proteine sono state analizzate tramite digestione triptica in gel e analisi di spettrometria di massa. Questa analisi ha permesso di identificare due enzimi che non sono coinvolti nel metabolismo dello zolfo ma appartengono ad una stessa via catabolica distinta da quella cui appartengono gli enzimi Dsz.The environmental hazard posed by the accumulation of huge amounts of used tires might be partly relieved by the implementation of methods for recycling natural rubber (NR) from waste tires. This approach requires rubber grinding and a process of devulcanization that breaks the sulfur-sulfur crosslinks among polymer chains. Several chemic al or mechanical methods are already used to devulcanize ground-rubber. However, each of them has drawbacks related either to the lack of specificity or to the use of hazardous chemicals. It would therefore be desirable to develop processes in which selective and specific reactions are carried out in mild conditions of temperature and pressure, without the use of hazardous compounds. In this view, the use of biocatalysts could be a valuable and ecological alternative. This study explores the possibility of applying enzymes to devulcanize rubber in a process of “biodevulcanization”. Since enzymes active in rubber devulcanization were not available at the beginning of this thesis, this research started with the analysis of microorganisms isolated from environmental samples contaminated with waste tires. The desulfuring properties of several bacteria were tested on the model substrate dibenzothiophene (DBT). A first in-vivo screening of microorganisms allowed the selection of a new strain of Rhodococcus sp. referred as AF21875. This microorganism was studied with two aims: assessing the presence of a metabolic pathway for DBT desulfurization already described in other bacteria and identifying new metabolic abilities and enzymes. In bacteria active in desulfurization, four enzymes co-operate in the reaction of desulfurization: DszA, DszB, DszC and DszD. The presence of the four corresponding dsz genes in the genomic DNA of Rhodococcus sp. AF21875 has been assessed. The four genes have been cloned in a strain of the bacterium Escherichia coli to allow for the production of recombinant Dsz enzymes. The three recombinant proteins DszA, DszC and DszD are soluble and were successfully purified. More difficult was the production of DszB that is poorly expressed in any experimental condition. In view of a biotechnological application, structural and stability studies were carried out on DszA, DszC and DszD enzymes. In particular, we investigated secondary structure and heat stability by circular dichroism, while protein stability in the presence of different organic solvents was studied by spectrofluorimetry. Enzymes activity on DBT was assessed by high performance liquid chromatography (HPLC) by detecting the formation of 2 -hydroxybiphenyl (HBP), the reaction product of DBT desulfurization. The desulfurization activity of the four enzymes was then tested on vulcanized natural rubber using Rubber Process Analyzer and Fourier Transform Infrared Spectroscopy to detect chemical modifications induced by the enzymatic treatment. These analyses revealed minor changes. Other studies should be performed to attribute such modifications to desulfurization. Overall, Dsz enzymes from Rhodococcus sp. AF21875 were found to be an interesting starting point for the application of protein engineering approaches aimed to improve not only their activity but also their stability. A differential proteomic analysis of Rhodococcus sp. AF21875 was performed to identify enzymatic activities related to sulfur metabolism and different from Dsz proteins. Total proteins, extracted from cells grown either in the presence or in the absence of DBT, were separated by two-dimensional electrophoresis, showing that DBT induces a few changes in the proteome of Rhodococcus sp. AF21875. Three proteins, belonging to a metabolic pathway different from the Dsz one were identified by in-gel tryptic digestion and mass spectrometry.
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Bhandari, Murari. « Investigating the role of DsbA enzymes in growth and virulence of uropathogenic Escherichia coli ». Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/120696/2/Murari_Bhandari_Thesis.pdf.
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This study set out to investigate the impact of inhibiting bacterial enzymes on pathogen growth and virulence as an alternative antimicrobial strategy to antibiotics. Results support the hypothesis that DsbA enzyme inhibition is a robust anti-virulence strategy that can 'disarm but not kill bacteria' using uropathogenic Escherichia coli as the model pathogen. These findings have enhanced the pharmacological importance of DsbA as an anti-virulence drug target and contribute to ongoing research that aims to develop DsbA inhibitors against different bacterial pathogens with diverse DsbA enzymes.
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Martin, Melanie. « Inhibitoren des Angiotensin Converting Enzyme (ACE) in hypoallergenen Säuglingsnahrungen ». Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1234543148442-91042.
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Als Schlüsselenzym im Renin-Angiotensin System übernimmt das Angiotensin Converting Enzyme (ACE) eine wichtige Rolle bei der Blutdruckregulierung. ACE spaltet das biologisch inaktive Angiotensin I zum vasokonstriktorisch wirksamen Angiotensin II, was zu einem Anstieg des Blutdruckes führt. Tier- und Humanstudien zeigten, dass die Aufnahme bekannter, aus dem Proteinabbau stammender ACE-Inhibitoren eine Absenkung des Blutdruckes bewirkte. In der Lebensmittelindustrie finden Hydrolysate von Milchproteinen, im speziellen von Molkenproteinen, Einsatz in hypoallergenen (HA) Säuglingsnahrungen. Obwohl das Phänomen einer ACE-Inhibierung durch HA-Nahrungen in vitro in der Literatur bereits Erwähnung fand, existieren bislang keine Angaben zu einer potentiellen Wirkung in vivo. In der vorliegenden Arbeit konnte für kommerzielle hypoallergene (HA) Säuglingsnahrung eine sehr starke ACE-Hemmung in vitro zeigen (IC50-Werte zwischen 20 und 104 mg Protein/liter), welche die für fermentierte Sauermilchprodukte dokumentierte Wirkung bei weitem überstieg.] Mittels RP-HPLC und ESI-TOF-MS konnte neben zahlreichen bekannten Peptiden mit ACE-hemmendem Effekt erstmals das aus der Primärsequenz von -Lactalbumin freigesetzte Dipeptid Ile-Trp in den HA-Nahrungen identifiziert und quantifiziert werden. Ile-Trp ist der bislang potenteste in Lebensmitteln nachgewiesene ACE-Inhibitor (IC50 = 0,7µM). HA-Nahrungen zeigten auch ex vivo im Zellsystem (HUVECs) einen stark ACE-hemmenden Effekt. Aus diesem Grunde wurde ein möglicher Einfluss der HA-Nahrungen auf den Blutdruck spontan hypertensiver Ratten untersucht. Hierfür wurden die Tiere im Rahmen einer Fütterungsstudie über 14 Wochen mit standardisiertem Futter, welchem HA-Nahrung (Gruppe 1), konventionelle Säuglingsnahrung (Gruppe 2) bzw. der bekannte ACE-Inhibitor Captopril (Gruppe 3) zugesetzt war, gefüttert. Eine vierte Gruppe mit Standardfutter diente als Kontrolle. Der Blutdruck wurde am wachen Tier nichtinvasiv mittels tail-cuff-Methode gemessen. Der systolische Blutdruck sank bei Verabreichung der HA-Nahrung nach 7 Wochen signifikant um 21 ± 8 mmHg ab im Vergleich zur Kontrollgruppe bzw. den mit konventioneller Säuglingsnahrung gefütterten Tieren. Captopril führte zur einer Blutdrucksenkung um 30 ± 7 mmHg.
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Ragnitz, Kerstin. « Immobilisierung und Stabilisierung der Hydantoinase und L-N-Carbamoylase aus Arthrobacter aurescens DSM 3747 ». [S.l. : s.n.], 2000. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB8926276.
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Mills, Landon C. « IMPACT OF CONFORMATIONAL CHANGE, SOLVATION ENVIRONMENT, AND POST-TRANSLATIONAL MODIFICATION ON DESULFURIZATION ENZYME 2'-HYDROXYBIPHENYL-2-SULFINATE DESULFINASE (DSZB) STABILITY AND ACTIVITY ». UKnowledge, 2019. https://uknowledge.uky.edu/cme_etds/105.
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Naturally occurring enzymatic pathways enable highly specific, rapid thiophenic sulfur cleavage occurring at ambient temperature and pressure, which may be harnessed for the desulfurization of petroleum-based fuel. One pathway found in bacteria is a four-step catabolic pathway (the 4S pathway) converting dibenzothiophene (DBT), a common crude oil contaminant, into 2-hydroxybiphenyl (HBP) without disrupting the carbon-carbon bonds. 2’-Hydroxybiphenyl-2-sulfinate desulfinase (DszB), the rate-limiting enzyme in the enzyme cascade, is capable of selectively cleaving carbon-sulfur bonds. Accordingly, understanding the molecular mechanisms of DszB activity may enable development of the cascade as industrial biotechnology. Based on crystallographic evidence, we hypothesized that DszB undergoes an active site conformational change associated with the catalytic mechanism. Moreover, we anticipated this conformational change is responsible, in part, for enhancing product inhibition. Rhodococcus erythropolis IGTS8 DszB was recombinantly produced in Escherichia coli BL21 and purified to test these hypotheses. Activity and the resulting conformational change of DszB in the presence of HBP were evaluated. The activity of recombinant DszB was comparable to the natively expressed enzyme and was competitively inhibited by the product, HBP. Using circular dichroism, global changes in DszB conformation were monitored in response to HBP concentration, which indicated that both product and substrate produced similar structural changes. Molecular dynamics (MD) simulations and free energy perturbation with Hamiltonian replica exchange molecular dynamics (FEP/λ-REMD) calculations were used to investigate the molecular-level phenomena underlying the connection between conformation change and kinetic inhibition. In addition to the HBP, MD simulations of DszB bound to common, yet structurally diverse, crude oil contaminates 2’2-biphenol (BIPH), 1,8-naphthosultam (NTAM), 2-biphenyl carboxylic acid (BCA), and 1,8-naphthosultone (NAPO) were performed. Analysis of the simulation trajectories, including root mean square fluctuation (RMSF), center of mass (COM) distances, and strength of nonbonded interactions, when compared with FEP/λ-REMD calculations of ligand binding free energy, showed excellent agreement with experimentally determined inhibition constants. Together, the results show that a combination of a molecule’s hydrophobicity and nonspecific interactions with nearby functional groups contribute to a competitively inhibitive mechanism that locks DszB in a closed conformation and precludes substrate access to the active site.
Limitations in DszB’s potential applications in industrial sulfur fixation are not limited to turnover rate. To better characterize DszB stability and to gain insight into ways by which to extend lifetime, as well as to pave the way for future studies in inhibition regulation, we evaluated the basic thermal and kinetic stability of DszB in a variety of solvation environments. Thermal stability of DszB was measured in a wide range of different commercially available buffer additives using differential scanning fluorimetry (DSF) to quickly identify favorable changes in protein melting point. Additionally, a fluorescent kinetic assay was employed to investigate DszB reaction rate over a 48 hr time period in a more focused group of buffer to link thermal stability to DszB life-time. Results indicate a concerningly poor short-term stability of DszB, with an extreme preference for select osmolyte buffer additives that only moderately curbed this effect. This necessitates a means of stability improvement beyond alteration of solvation environment. To this end, a more general investigation of glycosylation and its impact on protein stability was performed.
Post-translational modification of proteins occurs in organisms from all kingdoms life, with glycosylation being among the most prevalent of amendments. The types of glycans attached differ greatly by organism but can be generally described as protein-attached carbohydrate chains of variable lengths and degrees of branching. With great diversity in structure, glycosylation serves numerous biological functions, including signaling, recognition, folding, and stability. While it is understood that glycans fulfill a variety of important roles, structural and biochemical characterization of even common motifs and preferred rotamers is incomplete. To better understand glycan structure, particularly their relevance to protein stability, we modeled and computed the solvation free energy of 13 common N- and O-linked glycans in a variety of conformations using thermodynamic integration. N-linked glycans were modeled in the β-1,4-linked conformation, attached to an asparagine analog, while O-linked glycans were each modeled in both the α-1,4 and β-1,4-linked conformations attached to both serine and threonine analogs. Results indicate a strong preference for the β conformation and show a synergistic effect of branching on glycan solubility. Our results serve as a library of solvation free energies for fundamental glycan building blocks to enhance understanding of more complex protein-carbohydrate structures moving forward.
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Othman, Mohamad. « Characterisation and Control of 3-Deoxy-D-arabino-heptulosonate 7-phosphate Synthase from Geobacillus sp ». Thesis, University of Canterbury. Department of chemisty, 2014. http://hdl.handle.net/10092/10113.
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3-Deoxy-D-arabino heptulosonate 7-phosphate synthase (DAH7PS) catalyses the first step of the shikimate pathway, responsible for the biosynthesis of aromatic amino acids. This pathway is found in microorganisms, plants and apicomplexan parasites and its absence in mammals makes it a viable target for antimicrobial drug design. DAH7PS enzymes differ in the regulatory machinery that decorates the catalytic (β/α)8 barrel. Some DAH7PS enzymes are fused to chorismate mutase (CM), another enzyme in the shikimate pathway. This fusion protein is allosterically regulated by chorismate (CA) or prephenate (PA), the precursor of tyrosine and phenylalanine. It has been suggested that DAH7PS enzymes evolved these extensions to the core barrel for the sole purpose of regulation.
Geobacillus sp DAH7PS (GspDAH7PSWT) is a thermophilic type Iβ DAH7PS enzyme with an N-terminal CM domain fused through a linker region. This thesis describes the functional characterisation work carried out on GspDAH7PSWT, in attempt to help determine how DAH7PS enzymes evolved such diverse methods of regulation.
Chapter 2 describes the functional characterisation work carried out on the catalytic and regulatory domains of GspDAH7PSWT. The enzyme demonstrated both DAH7PS and CM activities with the DAH7PS domain determined to be metal dependent and most activated by Cd2+. PA completely inhibited the catalytic activity of GspDAH7PSWT, and AUC demonstrated an equilibrium exists between the dimeric and tetrameric quaternary states of the enzyme in solution.
Chapter 3 describes the domain truncation of GspDAH7PSWT carried out at the linker region in order to obtain two separate protein domains, the catalytic domain lacking the N-terminal domain (GspDAH7PSDAH7PS) and the regulatory domain without the catalytic domain (GspDAH7PSCM). Both variants were fully characterised, and information obtained from each domain was compared to the respective catalytic and regulatory domains of the wild-type enzyme, which was also characterised. Like GspDAH7PSWT, GspDAH7PSDAH7PS showed greatest activation in the presence of Cd2+, with other metals having varying effects on activation rates and stability of the enzyme. Both truncated variants followed Michaelis-Menten kinetics where GspDAH7PSDAH7PS was found to be more active than GspDAH7PSWT and unaffected by PA, whereas GspDAH7PSCM was a less efficient catalyst than the CM domain of GspDAH7PSWT. AUC demonstrated that in solution an equilibrium occurs between the monomeric and tetrameric oligomeric states of GspDAH7PSDAH7PS.
Chapter 4 summarises the findings of the thesis along with future directions of this research, combining the results obtained and expanding upon them. It is concluded that the catalytic regulatory CM domain supports both protein structure and allosteric regulation of GspDAH7PSWT
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Ubhi, Devinder Kaur. « Structural analysis and discovery of lead compounds for the fungal methionine synthase enzyme ». Thesis, 2013. http://hdl.handle.net/2152/28686.
Texte intégralRésumé :
Methionine synthases catalyze methyl transfer from 5-methyl-tetrahydrofolate (5-methyl-THF) to L-homocysteine (Hcy) in order to generate methionine (Met). Mammals, including humans, use a cobalamin dependent form, while fungi use a cobalamin independent protein called Met6p. The large structural differences between them make Met6p a potential anti-fungal drug target. Met6p is a 90 kDa protein with the active site located between two (βα)₈ barrels. The active site has a catalytic Zn²+ and binding sites for the two substrates, Hcy and folate. I present the crystal structures of three engineered variants of the Met6p enzyme from Candida albicans. I also solved Met6p in complex with several substrate and product analogs, including Hcy, Met, Gln, 5-methyl-THF-Glu₃ and Methotrexate-Glu₃ (MTX-Glu₃), and the bi-dentate ligand S-adenosyl homocysteine. Also described is a new fluorescence-based activity assay monitoring Hcy. Lastly, a high-throughput Differential Scanning Fluorimetry (DSF) assay was used to screen thousands of compounds in order to identify ligands which bind Met6p. My work details the mode of interaction of Hcy and folate with the Met6p protein. Several residues important to activity were discovered, like Asn 126 and Tyr 660, and proven to be important by site directed mutagenesis. Structural analysis revealed an important aspect of the mechanism. When Hcy binds to its pocket it makes strong ion pairs with the enzyme. In particular, 614 moves toward the substrate amine and triggers a rearrangement of active site loops; this draws the catalytic Zn²+ toward the Hcy thiol where a new ligand bond is formed, activating the thiol for methyl transfer. The work presented here lays the groundwork for structure based drug design and makes the development of Met6p specific bi-dentate ligands feasible. The fluorescence based activity assay I developed was successfully used to test the folate analog MTX-Glu₃, which inhibits with an IC₅₀ of ~4 mM. I also discovered our first bi-dentate ligand in the form of S-adenosyl homocysteine.text
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Ottenheim, Christoph, Katharina A. Werner, Wolfgang Zimmermann et Jin Chua Wu. « Improved endoxylanase production and colony morphology of Aspergillus niger DSM 26641 by g-ray induced mutagenesis ». 2015. https://ul.qucosa.de/id/qucosa%3A16854.
Texte intégralRésumé :
Aspergillus niger DSM 26641 was exposed to 60Co g-radiation to enhance the b-1,4-endoxylanase activity, restrict colony growth and improve robustness of pellets. The first promising mutant obtained after g-radiation of the fungal spores at 50-2000 Gy showed a restricted colony growth and an 82% enhancement in b-1,4-endoxylanase activity. The mutant was subjected to a second round of g-radiation at 1400 Gy generating a mutant with double the b-1,4-endoxylanase activity compared to the native strain. The selected final mutant, deposited as Aspergillus niger DSM 28712, showed a maximal saccharification activity of 26 U·ml-1 on xylan based broth, 48 U·ml-1 on lignocellulose hydrolysate and 375 U·ml-1 on lignocellulose hydrolysate supplemented with yeast extract and mineral salts.
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Dumaual, Carmen Michelle. « Expression and Function of the PRL Family of Protein Tyrosine Phosphatase ». 2013. http://hdl.handle.net/1805/3248.
Texte intégralRésumé :
Indiana University-Purdue University Indianapolis (IUPUI)The PRL family of enzymes constitutes a unique class of protein tyrosine phosphatase, consisting of three highly homologous members (PRL-1, PRL-2, and PRL-3). Family member PRL-3 is highly expressed in a number of tumor types and has recently gained much interest as a potential prognostic indicator of increased disease aggressiveness and poor clinical outcome for multiple human cancers. PRL-1 and PRL-2 are also known to promote a malignant phenotype in vitro, however, prior to the present study, little was known about their expression in human normal or tumor tissues. In addition, the biological function of all three PRL enzymes remains elusive and the underlying mechanisms by which they exert their effects are poorly understood. The current project was undertaken to expand our knowledge surrounding the normal cellular function of the PRL enzymes, the signaling pathways in which they operate, and the roles they play in the progression of human disease. We first characterized the tissue distribution and cell-type specific localization of PRL-1 and PRL-2 transcripts in a variety of normal and diseased human tissues using in situ hybridization. In normal, adult human tissues we found that PRL-1 and PRL-2 messages were almost ubiquitously expressed. Only highly specialized cell types, such as fibrocartilage cells, the taste buds of the tongue, and select neural cells displayed little to no expression of either transcript. In almost every other tissue and cell type examined, PRL-2 was expressed strongly while PRL-1 expression levels were variable. Each transcript was widely expressed in both proliferating and quiescent cells indicating that different tissues or cell types may display a unique physiological response to these genes. In support of this idea, we found alterations of PRL-1 and PRL-2 transcript levels in tumor samples to be highly tissue-type specific. PRL-1 expression was significantly increased in 100% of hepatocellular and gastric carcinomas, but significantly decreased in 100% of ovarian, 80% of breast, and 75% of lung tumors as compared to matched normal tissues from the same subjects. Likewise, PRL-2 expression was significantly higher in 100% of hepatocellular carcinomas, yet significantly lower in 54% of kidney carcinomas compared to matched normal specimens. PRL-1 expression was found to be associated with tumor grade in the prostate, ovary, and uterus, with patient gender in the bladder, and with patient age in the brain and skeletal muscle. These results suggest an important, but pleiotropic role for PRL-1 and PRL-2 in both normal tissue function and in the neoplastic process. These molecules may have a tumor promoting effect in some tissue types, but inhibit tumor formation or growth in others. To further elucidate the signaling pathways in which the PRLs operate, we focused on PRL-1 and used microarray and microRNA gene expression profiling to examine the global molecular changes that occur in response to stable PRL-1 overexpression in HEK293 cells. This analysis led to identification of several molecules not previously associated with PRL signaling, but whose expression was significantly altered by exogenous PRL-1 expression. In particular, Filamin A, RhoGDIalpha, and SPARC are attractive targets for novel mediators of PRL-1 function. We also found that PRL-1 has the capacity to indirectly influence the expression of target genes through regulation of microRNA levels and we provide evidence supporting previous observations suggesting that PRL-1 promotes cell proliferation, survival, migration, invasion, and metastasis by influencing multi-functional molecules, such as the Rho GTPases, that have essential roles in regulation of the cell cycle, cytoskeletal reorganization, and transcription factor function. The combined results of these studies have expanded our current understanding of the expression and function of the PRL family of enzymes as well as of the role these important signaling molecules play in the progression of human disease.
Chapitres de livres sur le sujet "Dsz enzymes"
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Vidal, A., Y. Ruiz, P. Suárez, Ana Alonso Martinez, A. E. Rossignoli, J. Blanco, O. Garcia et F. San Juan. « Accumulation of Okadaic Acid and Detoxifying Enzymes in the Digestive Gland of Mytilus galloprovincialis During Exposure to DSP ». Dans Molluscan Shellfish Safety, 217–25. Dordrecht : Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6588-7_19.
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Lucchesi, John C. « DNA repair and genomic stability ». Dans Epigenetics, Nuclear Organization & ; Gene Function, 173–83. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198831204.003.0015.
Texte intégralRésumé :
A number of pathways have evolved in order to repair DNA. Mismatch repair (MMR) operates when an improper nucleotide is used or when an insertion or deletion occurs during replication. Nucleotide excision repair (NER) repairs damage that distorts the DNA helix such as the presence of pyrimidine dimers induced by ultraviolet light. Base excision repair (BER) removes damaged or altered DNA bases that do not result in a conformational change in the chromatin. Single-strand break repair (SSBR) uses the same enzymatic steps as BER. Double-strand break (DSB) repair can involve either non-homologous end-joining (NHEJ) or homologous recombination (HR). In NHEJ, the broken DNA ends are joined directly. HR requires that one of the strands of the broken DNA molecule participates in the strand invasion of the sister chromatid. The site of the DSB must be modified to allow access to the repair machinery. This modification involves remodeling complexes, as well as histone-modifying enzymes.
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SMEETS, M. F. M., R. J. C. SLEBOS et A. C. BEGG. « DNA DSB MEASUREMENTS USING ENZYME TAILING AND PULSED FIELD GEL ELECTROPHORESIS ». Dans Radiation Research : A Twentieth-century Perspective, 306. Elsevier, 1991. http://dx.doi.org/10.1016/b978-0-12-168561-4.51035-0.
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« Tab le 2. Classification of enzymes in MODOMICS (December 2008). For each class, the number of enzymes and their ability to modify a certain nucleotide or its derivatives is given. The DSS in the rightmost column indicates enzymes having dual substrate specificity for different classes of RNAs, e.g. : tRNA and snRNA or tRNA and rRNA. » Dans DNA and RNA Modification Enzymes, 636–48. CRC Press, 2009. http://dx.doi.org/10.1201/9781498713153-41.
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Pietzsch, M., H. Oberreuter, B. Petrovska, K. Ragnitz et C. Syldatk. « Immobilization of hydantoin cleaving enzymes from Arthrobacter aurescens DSM 3747 - Effect of the coupling method on the stability of the L-N-carbamoylase ». Dans Progress in Biotechnology, 517–22. Elsevier, 1998. http://dx.doi.org/10.1016/s0921-0423(98)80077-4.
Texte intégralActes de conférences sur le sujet "Dsz enzymes"
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Iltchenko, Nikita, Jesse Beam et Ying Zha. « Applications and benefits of phospholipase A enzymes in seed oil processing ». Dans 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/rrjs3474.
Texte intégralRésumé :
Current market conditions have further driven focus on efficiency for oilseed producers. Phospholipases use for enzymatic degumming and refining has, therefore, become more attractive than ever. Since its introduction a decade ago, enzyme assisted seed oil processing has been demonstrated at many plants around the globe for its benefit on yield increase. With the learnings gained from the field, enzyme producers have brought out new generations of products to improve performance, as well as meeting new requirements of the oil plants, such as lower chemical usage, less byproducts and higher ease of use. We would like to demonstrate the applications and benefits of two new phospholipase A enzymes, being Phospholipase A1 (Purifine® PLA1) and Phospholipase A2 (Purifine® LM), which offers these new benefits to producers, crushing and refining. Often the biggest hurdle encountered in implementing enzyme technology is capital expenditure. DSM has worked to develop options for nearly all plants to ensure benefits from enzymatic degumming can be appreciated across the industry. The applications of these enzymes, including efforts needed to make plant changes to accommodate enzyme usage, are demonstrated herein.
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Alhajeri, Mubarak Muhammad, Jenn-Tai Liang et Reza Barati Ghahfarokhi. « Polyelectrolyte Multilayered Nanoparticles as Nanocontainers for Enzyme Breakers During Hydraulic Fracturing Process ». Dans SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/205981-ms.
Texte intégralRésumé :
Abstract In this study, Layer-by-Layer (LbL) assembled polyelectrolyte multilayered nanoparticles were developed as a technique for targeted and controlled release of enzyme breakers. Polyelectrolyte multilayers (PEMs) were assembled by means of alternate electrostatic adsorption of polyanions and polycations using colloidal structure of polyelectrolyte complexes (PECs) as LbL building blocks. High enzyme concentrations were introduced into polyethyleneimine (PEI), a positively charged polyelectrolyte solution, to form an electrostatic PECs with dextran sulfate (DS), a negatively charged polyelectrolyte solution. Under the right concentrations and pH conditions, PEMs were assembled by alternating deposition of PEI with DS solutions at the colloidal structure of PEI-DS complexes. Stability and reproducibility of PEMs were tested over time. This work demonstrates the significance of PEMs as a technique for the targeted and controlled release of enzymes based on their high loading capacity, high capsulation efficiency, and extreme control over enzyme concentration. Entrapment efficiency (EE%) of polyelectrolyte multilayered nanoparticles were evaluated using concentration measurement methods as enzyme viscometric assays. Controlled release of enzyme entrapped within PEMs was sustained over longer time periods (> 18 hours) through reduction in viscosity, and elastic modulus of borate-crosslinked hydroxypropyl guar (HPG). Long-term fracture conductivity tests at 40℃ under closure stresses of 1,000, 2,000, and 4,000 psi revealed high fracture clean-up efficiency for fracturing fluid mixed with enzyme-loaded PEMs nanoparticles. The retained fracture conductivity improvement from 25% to 60% indicates the impact of controlled distribution of nanoparticles in the filter cake and along the entire fracture face as opposed to the randomly dispersed unentrapped enzyme. Retained fracture conductivity was found to be 34% for fluid systems containing conventional enzyme-loaded PECs. Additionally, enzyme-loaded PEMs demonstrated enhanced nanoparticle distribution, high loading and entrapment efficiency, and sustained release of the enzyme. This allows for the addition of higher enzyme concentrations without compromising the fluid properties during a treatment, thereby effectively degrading the concentrated residual gel to a greater extent. Fluid loss properties of polyelectrolyte multilayered nanoparticles were also studied under static conditions using a high-pressure fluid loss cell. A borate-crosslinked HPG mixed with nanoparticles was filtered against core plugs with similar permeabilities. The addition of multilayered nanoparticles into the fracturing fluid was observed to significantly improve the fluid- loss prevention effect. The spurt-loss coefficient values were also determined to cause lower filtrate volume than those with crosslinked base solutions. The PEI-DS complex bridging effects revealed a denser, colored filter cake indicating a relatively homogenous dispersion and properly sized particles in the filter cake.
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Ramos, Maria, Pedro Ferreira, Sérgio Sousa et Pedro Fernandes. « Accelerating the DszD enzyme for the Biodesulfurization of Crude Oil and Derivatives ». Dans MOL2NET 2018, International Conference on Multidisciplinary Sciences, 4th edition. Basel, Switzerland : MDPI, 2018. http://dx.doi.org/10.3390/mol2net-04-06087.
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Yu, Hansong, Shuang Qu, Yuhua Wang, Chunhong Piao, Junmei Liu et Yaohui Hu. « Cloning and Site-specific Mutagenesis of DS Enzyme Gene of Corynebacterium glutamicum ». Dans 2015 International Conference on Materials, Environmental and Biological Engineering. Paris, France : Atlantis Press, 2015. http://dx.doi.org/10.2991/mebe-15.2015.26.
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Kulikov, D. S., V. V. Kolpakova, V. A. Gulakova, R. V. Ulanova et L. V. Chumikina. « Biotechnological processes of pea grain processing to produce concentrated protein preparations ». Dans CURRENT STATE, PROBLEMS AND PROSPECTS OF THE DEVELOPMENT OF AGRARIAN SCIENCE. Federal State Budget Scientific Institution “Research Institute of Agriculture of Crimea”, 2020. http://dx.doi.org/10.33952/2542-0720-2020-5-9-10-92.
Texte intégralRésumé :
A mathematical model has been developed for the dependence of the solubility of pea flour protein on technological factors (concentration of enzyme preparations, duration of fermentation, hydromodule). The optimal technological parameters were determined at 1 + 2 stages of fermentation (concentration of enzyme preparations 170 units/g of DS or 1.5 %/g of protein, duration of fermentation was 4 hours, water module 1:15), at which the solubility and yield of pea protein reached 60 % of total content in raw materials. New information has been obtained on the effect of ultrasonic treatment on a suspension of pea flour to increase protein yield by 23–24 % compared with a control sample with an ultrasound wave amplitude of 10 microns and a processing time of 3 minutes, the final solubility is 83–84 %. The resulting protein product was characterized by high protein content, complementary amino acid composition; it is recommended for use in food purposes.
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Niederst, P. N., M. Asbach, M. Ott et R. E. Zimmermann. « IN VITRO REACTION MODELS OF THROMBIN AND ITS PHYSIOLOGICAL INHIBITOR ANTITHROMBIN III IN THE PRESENCE OF HEPARIN ». Dans XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644356.
Texte intégralRésumé :
Antithrombin III (AT III) neutralizes thrombin and other serine proteases of plasma coagulation system by forming a stable 1:1 covalent complex. The inhibition rates are greatly increased by the potent catalyst heparin. The catalytic mechanism of heparin was studied in the presence of dextran sulfate (DS), a thrombin-binding sulfated Polysaccharid. DS did not influence the reaction of AT III with heparin and the amidolytic activity of thrombin, but preincubation with thrombin could inhibit the catalytic activity of heparin in the reaction of thrombin with AT III. We conclude that the reaction of heparin with enzyme and inhibitor, thus forming a ternary complex, is necessary for its catalytic activity.It is known that heparin also converts AT III from an inhibitor to a substrate for thrombin in a dose dependent manner. By cleavage of the reaction site bound Arg(385)-Ser(386) an AT III-fragment (MG 50000 d) occurs, which has a decreased affinity to heparin and does not inhibit F I la. At physiological ionic strength we have only measured a small percentage of AT 111-proteolysis (4%, 1 U/ml Hep). The extent of AT III-fragment formation could be enhanced by lowering the ionic strength (max 44%, 1 U/ml Hep., 1=0,02).
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Silva, Bruno Vinícius Diniz e., Brunna Rodrigues de Oliveira, Larissa Silva Magalhães, Kamila Cardoso dos Santos, Livia Melo Vilar, Vanessa Salete de Paula, Karlla Antonieta Amorim Caetano, Sheila Araújo Teles et Megmar Aparecida dos Santos Carneiro. « Seroepidemiological study of herpes simplex virus type 2 (HSV-2) infection in transgender women in Goiás ». Dans XIII Congresso da Sociedade Brasileira de DST - IX Congresso Brasileiro de AIDS - IV Congresso Latino Americano de IST/HIV/AIDS. Zeppelini Editorial e Comunicação, 2021. http://dx.doi.org/10.5327/dst-2177-8264-202133p058.
Texte intégralRésumé :
Introduction: Herpes simplex virus type 2 (HSV-2) causes lesions in the orolabial and anogenital region that last for a lifetime. Data show that about 491.5 million people live with HSV-2. Objective: The aim of this study was to evaluate the epidemiological profile of HSV-2 infection in a population of transgender women in Goiânia-GO and cities in the interior of the state. Methods: This is a cross-sectional study that estimates the prevalence of HSV-2 in transgender women residing or in transit in the metropolitan region of Goiânia and cities in the interior of the state. The Respondent-Driven Sampling (RDS) method was used for recruitment (sample size), the prevalence of HSV-2 was assessed by enzyme immunoassay. Statistical analyses were performed using the Statistical Package for the Social Science (SPSS). The database was analyzed to generate an adjusted prevalence of the characteristics of the study population. The study was approved by the Ethics Committee of the Universidade Federal de Goiás. Results: The prevalence was 8.2% (95% CI 5.0-12.2) for anti-HSV-2 IgM and 70.0% (95% CI 63.0-77.3) for anti-HSV-2 IgG; the bivariate analysis showed an association between positivity by IgG HSV-2 and age >30 years (p<0.0001), exchange of sex for money/drugs or consumer goods (p=0.002), more than 20 sexual partnerships in the past 7 days (p=0.001), and insertive anal sex (p=0.011); in the multivariate analysis, age ≥30 years (p=0.001) and more than 20 sexual partnerships in the past 7 days (p=0.008) were shown statistically related to HSV-2 infection. Conclusion: The data showed a high seroprevalence of HSV-2 among transgender women in the state of Goiás, indicating the need to develop public policies aimed at sexual education and improve this population’s health conditions.
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Castro, Ana Rita Motta, Livia Lima, Larissa Bandeira, Selma Gomes, Barbara Lago, Grazielli Rezende et Gabriela Alves Cesar. « Hepatitis B : changes in epidemiological features of Afrodescendant communities in Central Brazil ». Dans XIII Congresso da Sociedade Brasileira de DST - IX Congresso Brasileiro de AIDS - IV Congresso Latino Americano de IST/HIV/AIDS. Zeppelini Editorial e Comunicação, 2021. http://dx.doi.org/10.5327/dst-2177-8264-202133p142.
Texte intégralRésumé :
Introduction: Hepatitis B virus (HBV) infection is still a concern in vulnerable populations. In a study performed by our team in 1999–2003 in two Afro-Brazilian communities, Furnas dos Dionísios (FD) and São Benedito (SB), high prevalence rates of HBV exposure (42.7% and 16.0%, respectively), high susceptibility to HBV (55.3% and 63.0%, respectively) and low HBV vaccination like profile rates (2.0% and 21.0%, respectively) were observed. Objective: In 2015–2016, we reassessed epidemiological and molecular features of HBV in these two communities to verify the impact of health actions adopted in the past years. Methods: Serum samples were screened by enzyme-linked immunosorbent assay (ELISA) for the presence of HBsAg, hepatitis B core antibody (total anti-HBc), and hepatitis B surface antibody (anti-HBs) (Biokit S.A., Barcelona, Spain). Cobas® e601 analyzer (Roche Diagnostics, Mannheim, Germany) was used to test the presence of HBeAg, anti- -HBe, and anti-HBc IgM in HBsAg-positive samples. The complete pre-S/S HBV region (nt 2826–nt 841) was amplified by semi-nested polymerase chain reaction (PCR). Results: The prevalence rate of HBV exposure among the enrolled 331 subjects was 35.3% in FD and 21.8% in SB. HBV chronic infection (5.8% in FD, 4.9% in SB) remained high. The rate of HBV vaccination like profile rate increased from 10.7% to 43.5% (2.0%–45.9% in FD, 21.0%–39.5% in SB), while susceptible subjects declined from 58.9% to 26.3% (55.3%– 18.8% in FD, 63.0%–38.7% in SB). Among 18 HBsAg-positive samples, 13 were successfully sequenced (pre-S/S region). Phylogenetic analyses showed that all isolates belong to HBV subgenotype A1, clustering within the Asian-American clade. Conclusion: Despite the maintenance of high prevalence rate of HBV exposure over these 13 years of surveillance, significant improvements were observed, reinforcing the importance of facilitated HBV vaccination to difficult-to-access population to close gaps in prevention.
Rapports d'organisations sur le sujet "Dsz enzymes"
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Wilson, Thomas E., Avraham A. Levy et Tzvi Tzfira. Controlling Early Stages of DNA Repair for Gene-targeting Enhancement in Plants. United States Department of Agriculture, mars 2012. http://dx.doi.org/10.32747/2012.7697124.bard.
Texte intégralRésumé :
Gene targeting (GT) is a much needed technology as a tool for plant research and for the precise engineering of crop species. Recent advances in this field have shown that the presence of a DNA double-strand break (DSB) in a genomic locus is critical for the integration of an exogenous DNA molecule introduced into this locus. This integration can occur via either non-homologous end joining (NHEJ) into the break or homologous recombination (HR) between the broken genomic DNA and the introduced vector. A bottleneck for DNA integration via HR is the machinery responsible for homology search and strand invasion. Important proteins in this pathway are Rad51, Rad52 and Rad54. We proposed to combine our respective expertise: on the US side, in the design of zincfinger nucleases (ZFNs) for the induction of DNA DSBs at any desired genomic locus and in the integration of DNA molecules via NHEJ; and on the Israeli side in the HR events, downstream of the DSB, that lead to homology search and strand invasion. We sought to test three major pathways of targeted DNA integration: (i) integration by NHEJ into DSBs induced at desired sites by specially designed ZFNs; (ii) integration into DSBs induced at desired sites combined with the use of Rad51, Rad52 and Rad54 proteins to maximize the chances for efficient and precise HR-mediated vector insertion; (iii) stimulation of HR by Rad51, Rad52 and Rad54 in the absence of DSB induction. We also proposed to study the formation of dsT-DNA molecules during the transformation of plant cells. dsT-DNA molecules are an important substrate for HR and NHEJ-mediatedGT, yet the mode of their formation from single stranded T-DNA molecules is still obscure. In addition we sought to develop a system for assembly of multi-transgene binary vectors by using ZFNs. The latter may facilitate the production of binary vectors that may be ready for genome editing in transgenic plants. ZFNs were proposed for the induction of DSBs in genomic targets, namely, the FtsH2 gene whose loss of function can easily be identified in somatic tissues as white sectors, and the Cruciferin locus whose targeting by a GFP or RFP reporter vectors can give rise to fluorescent seeds. ZFNs were also proposed for the induction of DSBs in artificial targets and for assembly of multi-gene vectors. We finally sought to address two important cell types in terms of relevance to plant transformation, namely GT of germinal (egg) cells by floral dipping, and GT in somatic cells by root and leave transformation. To be successful, we made use of novel optimized expression cassettes that enable coexpression of all of the genes of interest (ZFNs and Rad genes) in the right tissues (egg or root cells) at the right time, namely when the GT vector is delivered into the cells. Methods were proposed for investigating the complementation of T-strands to dsDNA molecules in living plant cells. During the course of this research, we (i) designed, assembled and tested, in vitro, a pair of new ZFNs capable of targeting the Cruciferin gene, (ii) produced transgenic plants which expresses for ZFN monomers for targeting of the FtsH2 gene. Expression of these enzymes is controlled by constitutive or heat shock induced promoters, (iii) produced a large population of transgenic Arabidopsis lines in which mutated mGUS gene was incorporated into different genomic locations, (iv) designed a system for egg-cell-specific expression of ZFNs and RAD genes and initiate GT experiments, (v) demonstrated that we can achieve NHEJ-mediated gene replacement in plant cells (vi) developed a system for ZFN and homing endonuclease-mediated assembly of multigene plant transformation vectors and (vii) explored the mechanism of dsTDNA formation in plant cells. This work has substantially advanced our understanding of the mechanisms of DNA integration into plants and furthered the development of important new tools for GT in plants.