Articles de revues : « Catalasi »

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Fusaroli, Federica. « La traduzione della «Somme le roi» tra Occitania e Catalogna : primi sondaggi ». Mot so razo 20 (25 janvier 2022) : 1. http://dx.doi.org/10.33115/udg_bib/msr.v20i0.22744.

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RIASSUNTO: Il presente lavoro mira a fornire nuovi appunti sulle conoscenze circa la traduzione catalana della Somme le roi, compendio morale francese composto nel 1279 dal domenicano Frère Laurent e di grande successo lungo tutto il xiv secolo. Le forti analogie con la versione occitanica della Somme, nota anche come Libre de vicis et de vertutz, lasciano presumere che il testo catalano discenda proprio dalla traduzione occitana e non dall’originale francese. Il caso di studio è reso difficile dalla mancanza di lezioni erronee imputabili al processo di traduzione e dalle complicazioni imputabili alla probabile concomitanza di più fonti, in occitano e in francese, dietro l’allestimento della versione catalana. In ragione di ciò, il contributo si sofferma a illustrare le due tradizioni testuali – catalana e occitana – mettendo a confronto i dati tratti dall’edizione critica del Libre de vicis et vertutz, di futura pubblicazione, con lo studio di Wittlin (1983) sul testo catalano. Il discorso si concentra principalmente su due questioni cruciali: la reductio ad unum dei testimoni catalani e la scelta di includere nella recensio occitana un testimone trascritto in catalano. ABSTRACT: This paper aims at updating the scholarship on the 14th-century Catalan translation of the French moral compendium known as Somme le roi. The relevant similarities between the texts demonstrate that the Catalan version directly depends on the Occitan translation, known as Libre de vicis et de vertutz. Therefore, the paper illustrates both the Catalan and the Occitan textual traditions and compares the results of my critical edition of the Libre de vicis et vertutz with Wittlin’s study (1983) on the Catalan text. This examination will focus on two main critical issues: the reductio ad unum of all the Catalan manuscripts and the choice to include a Catalan manuscript in the Occitan recensio.

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Hidayati, Nur, Rahmah Puspita Sari et Herry Purnama. « Catalysis of glycerol acetylation on solid acid catalyst : a review ». Jurnal Kimia Sains dan Aplikasi 23, n^o 12 (14 janvier 2021) : 414–23. http://dx.doi.org/10.14710/jksa.23.12.414-423.

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Biodiesel is a substitute fuel that is environmentally friendly, biodegradable, and sustainable. The need for biodiesel continues to increase. Biodiesel is made through the process of transesterification of triglycerides and alcohol. Glycerol is a side-effect of biodiesel products with a capacity of 10% of the total weight of its production. Glycerol is the simplest glyceride compound and has several functions as a primary ingredient in chemical production. Through acetylation, glycerol is converted to a material that has a higher sale value. Both homogeneous and heterogeneous catalysts are the acetylation approach to achieve the desired product, namely acetyl glycerol esters (mono-, di- and triacetin). However, in the process, the catalyst’s type and characteristics significantly affect the yield and conversion of the product and the deactivation or reusability of the catalyst, which can inhibit the catalyst’s utilization and effectiveness; therefore, it must be studied further. Besides, the parameters that affect the reaction will also be assessed.

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Ripa, Valentina. « Omaggio a Joan Vinyoli ». SCRIPTA. Revista Internacional de Literatura i Cultura Medieval i Moderna 5, n^o 5 (12 juin 2015) : 305. http://dx.doi.org/10.7203/scripta.5.6377.

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Riassunto: In continuità con l’omaggio a Joan Vinyoli organizzato a Roma nel 2014, si propongono le traduzioni in italiano di alcuni suoi componimenti, con testo a fronte. Parole chiave: Joan Vinyoli, traduzione dal catalano all’italiano, poesia catalana del Novecento. Abstract: In continuity with the Joan Vinyoli Tribute organized in Rome in December 2014, I propose the translation from Catalan to Italian of some of his poems. Keywords: Joan Vinyoli, translation from Catalan to Italian, twentieth-century Catalan poetry.

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Ortega-Caballero, Fernando, et Mikael Bols. « Cyclodextrin derivatives with cyanohydrin and carboxylate groups as artificial glycosidases ». Canadian Journal of Chemistry 84, n^o 4 (1 avril 2006) : 650–58. http://dx.doi.org/10.1139/v06-039.

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Two cyclodextrin derivatives (1 and 2) were prepared in an attempt to create glycosidase mimics with a general acid catalyst and a nucleophilic carboxylate group. The catalysts 1 and 2 were found to catalyse the hydrolysis of 4-nitrophenyl β-D-glucopyranoside at pH 8.0, but rapidly underwent decomposition with loss of hydrogen cyanide to convert the cyanohydrin to the corresponding aldehyde. The initial rate of the catalysis shows that the cyanohydrin group in these molecules functions as a good catalyst, but that the carboxylate has no positive effect. The decomposition product aldehydes display little or no catalysis. A mechanism for the decomposition is suggested.Key words: biomimicry, enzyme model, kinetics, intramolecular reaction.

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Puigmalet, Joan. « Un vocabulari pornogràfic francès-català inèdit ». SCRIPTA. Revista Internacional de Literatura i Cultura Medieval i Moderna 3, n^o 3 (28 juin 2014) : 291. http://dx.doi.org/10.7203/scripta.3.3824.

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Resum: Antoni Bulbena Tosell és autor d’un manuscrit, i inèdit, vocabulari pornogràfic francès-català català-francès, la Flora pornogràfica francesa: suplement al argot francès / Flore pornographique catalane: supplément à l’argot catalan. És una obra d’aproximadament l’any 1921 que, per la seva temàtica, ell mateix reservava per a no publicar-se. Bulbena és autor d’una discutida obra lingüística, entre la qual trobem diferents diccionaris, alguns d’ells entre el català i el francès. El darrer que publicà és el Diccionari de les lléngues francesa & catalana / Dictionnaire catalan-français (1921) que inclou dos apèndixs, un «Vocabulari d’argot francès» i un «Vocabulari d’argot catalan». La Flora és, així, un suplement al lèxic pornogràfic d’aquest diccionari. Per altra banda, el títol de Flora pornogràfica sembla fer referència a una obra de la lexicografia francesa que recull mots obscens presents a obres d’Emile Zola i altres escriptors naturalistes, La flore pornographique (1883), d’Ambroise Macrobe. Els mots d’argot sexual de la Flora, amb un especial focus temàtic en la prostitució, tenen interès lingüístic i cultural tant per a la llengua catalana com per a la llengua francesa. Paraules clau: Antoni Bulbena, Flora pornogràfica, lexicografia, català, francès. Abstract: Antoni Bulbena Tosell is the author of an unpublished, pornographic vocabulary French-Catalan Catalan-French, a manuscript called the Flora pornogràfica francesa: suplement al argot francès / Flore pornographique catalane: supplément à l’argot catalan. It was written around 1921 and reserved for not being published. Bulbena is the author of a controversial linguistic work, among which are various dictionaries, some of them between Catalan and French. The latest is the Diccionari de les lléngues francesa & catalana / Dictionnaire catalan-français (1921), that includes two appendixes, a «Vocabulari d’argot francès» and a «Vocabulari d’argot catalan». The Flora is thus a pornographic supplement to the lexicon of these vocabularies. Moreover, the title Flora pornogràfica seems to refer to a pornographic French lexicography work that contains obscene words from books by Émile Zola and other naturalist writers: La flore pornographique (1883) by Ambroise Macrobe. Slang sexual terms from the Bulbena’s Flora, with a special focus on the theme of prostitution, have linguistic and cultural interest both for the Catalan and the French language Keywords: Antoni Bulbena, Flora pornogràfica, lexicography, Catalan, French.

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Kato, Shigeru, Takafumi Ueno, Shunichi Fukuzumi et Yoshihito Watanabe. « Catalase Reaction by Myoglobin Mutants and Native Catalase ». Journal of Biological Chemistry 279, n^o 50 (2 septembre 2004) : 52376–81. http://dx.doi.org/10.1074/jbc.m403532200.

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The catalase reaction has been studied in detail by using myoglobin (Mb) mutants. Compound I of Mb mutants (Mb-I), a ferryl species (Fe(IV)=O) paired with a porphyrin radical cation, is readily prepared by the reaction with a nearly stoichiometric amount ofm-chloroperbenzoic acid. Upon the addition of H2O2to an Mb-I solution, Mb-I is reduced back to the ferric state without forming any intermediates. This indicates that Mb-I is capable of performing two-electron oxidation of H2O2(catalatic reaction). Gas chromatography-mass spectroscopy analysis of the evolved O2from a 50:50 mixture of H218O2/H216O2solution containing H64D or F43H/H64L Mb showed the formation of18O2(m/e= 36) and16O2(m/e= 32) but not16O18O (m/e= 34). This implies that O2is formed by two-electron oxidation of H2O2without breaking the O-O bond. Deuterium isotope effects on the catalatic reactions of Mb mutants and catalase suggest that the catalatic reactions ofMicrococcus lysodeikticuscatalase and F43H/H64L Mb proceed via an ionic mechanism with a small isotope effect of less than 4.0, since the distal histidine residue is located at a proper position to act as a general acid-base catalyst for the ionic reaction. In contrast, other Mb mutants such as H64X (Xis Ala, Ser, and Asp) and L29H/H64L Mb oxidize H2O2via a radical mechanism in which a hydrogen atom is abstracted by Mb-I with a large isotope effect in a range of 10–29, due to a lack of the general acid-base catalyst.

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Yuzugullu, Yonca, Chi H. Trinh, Lucy Fairhurst, Zumrut B. Ogel, Michael J. McPherson et Arwen R. Pearson. « Investigating the active centre of theScytalidium thermophilumcatalase ». Acta Crystallographica Section F Structural Biology and Crystallization Communications 69, n^o 4 (28 mars 2013) : 369–75. http://dx.doi.org/10.1107/s1744309113004211.

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Almost all monofunctional haem catalases contain a highly conserved core containing the active site, which is connected to the exterior of the enzyme by three channels. These channels have been identified as potential routes for substrate flow and product release. To further investigate the role of these molecular channels, a series of mutants ofScytalidium thermophilumcatalase were generated. The three-dimensional structures of four catalase variants, N155A, V123A, V123C and V123T, have been determined at resolutions of 2.25, 1.93, 1.9 and 1.7 Å, respectively. The V123C variant contains a new covalent bond between the S atom of Cys123 and the imidazole ring of the essential His82. This variant enzyme has only residual catalase activity and contains haembinstead of the normal haemd. The H82A variant demonstrates low catalase and phenol oxidase activities (0.2 and 20% of those of recombinant wild-type catalase–phenol oxidase, respectively). The N155A and N155H variants exhibit 4.5 and 3% of the wild-type catalase activity and contain haemd, showing that Asn155 is essential for catalysis but is not required for the conversion of haembto haemd. Structural analysis suggests that the cause of the effect of these mutations on catalysis is the disruption of the ability of dioxygen substrates to efficiently access the active site. Additional mutants have been characterized biochemically to further probe the roles of the different channels. Introducing smaller or polar side chains in place of Val123 reduces the catalase activity. The F160V, F161V and F168V mutants show a marked decrease in catalase activity but have a much lower effect on the phenol oxidase activity, despite containing substoichiometric amounts of haem.

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Martí-Badia, Adrià. « Llengua i identitat en l’obra de Benvingut Oliver i Joan Baptista Perales ». SCRIPTA. Revista Internacional de Literatura i Cultura Medieval i Moderna 6, n^o 6 (29 décembre 2015) : 120. http://dx.doi.org/10.7203/scripta.6.7827.

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Resum: Aquest treball es proposa analitzar la reacció dels erudits valencians Benvingut Oliver i Joan Baptista Perales davant els postulats de la filologia romànica sobre el català en la segona meitat del segle XIX. A més, tractem de relacionar la posició d’Oliver i Perales amb altres erudits i escriptors del moviment reinaixencista i amb la consciència de comunitat lingüística compartida amb catalans, balears i nord-catalans. A partir de la meitat del Vuitcents els romanistes germànics funden la filologia romànica i constaten que el català és el nom de la llengua pròpia dels territoris de llengua catalana, diferent de l’occità i sense res a veure amb el llemosí amb què era conegut des de principis del segle xvi. Aquests postulats respecte a la identitat i el nom de la llengua catalana són ràpidament rebuts i acceptats a Catalunya; i a les Illes Balears i a la Catalunya del Nord foren rebuts positivament amb molt poques excepcions. Però no així al País Valencià, on només una minoria d’erudits com Benvingut Oliver i Joan B. Perales –entre d’altres– va acceptar i divulgar aquests postulats. Paraules clau: Segle XIX, Nom i identitat de la llengua catalana, Renaixença Valenciana, Benvingut Oliver, Joan Baptista Perales Abstract: This paper analyses the reaction of the Valencian scholars Benvingut Oliver and Joan Baptista Perales against postulates on the Catalan Romance philology in the middle of the nineteenth century. Moreover, this work tries to relate Oliver and Perales position with others scholars and writers of the Reinaixença Valenciana movement and the awareness of linguistic community shared with Catalan speakers from Catalonia, the Balearic Islands and North Catalonia. From the middle of the nineteenth century the German romanists found the Romance philology. They established “Catalan” as the name of the language of the Catalan-speaking areas. Even this is different from Occitan and has nothing to do with Limousin, which was known by this name since the early sixteenth century. Regarding the identity and the name of the Catalan language, these assumptions are quickly received and assumed in Catalonia. Although in the Balearic Islands and North Catalonia they were received positively with very few exceptions. Whereas in Valencia, only a minority of scholars like Benvingut Oliver and Joan B. Perales –among others– accepted and disseminated these postulates. Keywords: Nineteenth century, Name and identity of the Catalan language, Valencian Renaissance, Benvingut Oliver, Joan Baptista Perales

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Jiménez-Salcedo, Juan. « Quelques pistes méthodologiques en démolinguistique : la langue catalane et son Enquête d’usages linguistiques ». Articles 40, n^o 1 (9 décembre 2011) : 13–38. http://dx.doi.org/10.7202/1006630ar.

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Notre article présente la méthodologie et les résultats de l’Enquesta d’usos lingüístics 2008 (EULP08), une enquête menée par l’Institut catalan de la statistique (Idescat), dont l’objectif principal et de dresser un portrait des usages linguistiques de la population catalane, et qui se base sur une conceptualisation ouverte et dynamique des catégorisations linguistiques. Nous pensons que la méthode de travail privilégiée par les statisticiens catalans peut contribuer à éclairer plusieurs aspects de la démolinguistique canadienne et québécoise.

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Paris, Sophie, Deborah Wysong, Jean-Paul Debeaupuis, Kazutoshi Shibuya, Bruno Philippe, Richard D. Diamond et Jean-Paul Latgé. « Catalases of Aspergillus fumigatus ». Infection and Immunity 71, n^o 6 (juin 2003) : 3551–62. http://dx.doi.org/10.1128/iai.71.6.3551-3562.2003.

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ABSTRACT Upon infection of a host, the pathogenic fungus Aspergillus fumigatus is attacked by the reactive oxygen species produced by phagocytic cells. Detoxification of hydrogen peroxide by catalases was proposed as a way to overcome this host response. A. fumigatus produces three active catalases; one is produced by conidia, and two are produced by mycelia. The mycelial catalase Cat1p was studied previously. Here we characterized the two other catalases, their genes, and the phenotypes of gene-disrupted mutants. CatAp, a spore-specific monofunctional catalase, is resistant to heat, metal ions, and detergent. This enzyme is a dimeric protein with 84.5-kDa subunits. The 749-amino-acid polypeptide exhibits high levels of similarity to the Aspergillus nidulans CatA catalase and to bacterial catalase HPII of Escherichia coli. In spite of increased sensitivity to H2O2, killing of ΔcatA conidia by alveolar macrophages and virulence in animals were similar to the killing of conidia by alveolar macrophages and virulence in animals observed for the wild type. In contrast to the Cat1p and CatAp catalases, the mycelial Cat2p enzyme is a bifunctional catalase-peroxidase and is sensitive to heat, metal ions, and detergent. This enzyme, an 82-kDa monomer, is homologous to catalase-peroxidases of several fungi and bacteria. Surprisingly, mycelium of the double Δcat1Δcat2 mutant with no catalase activity exhibited only slightly increased sensitivity to H2O2 and was as sensitive to killing by polymorphonuclear neutrophils as mycelium of the wild-type strain. However, this mutant exhibited delayed infection in the rat model of aspergillosis compared to infection by the wild-type strain. These results indicate that conidial catalase is not a virulence factor and that mycelial catalases transiently protect the fungus from the host.

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Kaplunenko, Volodymyr, et Mykola Kosinov. « Electric field - induced catalysis. Laws of field catalysis ». InterConf, n^o 26(129) (18 octobre 2022) : 332–51. http://dx.doi.org/10.51582/interconf.19-20.10.2022.037.

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Abstract.The article explores a new type of catalysis - electric field catalysis. The laws of field catalysis are given. The characteristics of the electric field are determined, which set the values of the characteristics of the field catalysis. Field catalysis and field catalyst do not fit into the traditional definition of catalysis and catalyst, which may require a revision of the terminology of catalysis. The field is a more versatile catalyst compared to material catalysts, both in terms of its application to a wider range of chemical reactions, and in the ability to control the rate and selectivity. It is shown that a common donor-acceptor mechanism of catalysis is realized in heterogeneous and field catalysis. Generalized formulas are obtained, from which, as partial results, the laws of heterogeneous and field catalysis follow. New definitions of catalyst and field catalysis are given. The class of material catalysts has been expanded and supplemented with field catalysts.

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Kawasaki, Laura, et Jesús Aguirre. « Multiple Catalase Genes Are Differentially Regulated in Aspergillus nidulans ». Journal of Bacteriology 183, n^o 4 (15 février 2001) : 1434–40. http://dx.doi.org/10.1128/jb.183.4.1434-1440.2001.

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ABSTRACT Detoxification of hydrogen peroxide is a fundamental aspect of the cellular antioxidant responses in which catalases play a major role. Two differentially regulated catalase genes, catA andcatB, have been studied in Aspergillus nidulans. Here we have characterized a third catalase gene, designated catC, which predicts a 475-amino-acid polypeptide containing a peroxisome-targeting signal. With a molecular mass of 54 kDa, CatC shows high similarity to other small-subunit monofunctional catalases and is most closely related to catalases from other fungi, Archaea, and animals. In contrast, the CatA (∼84 kDa) and CatB (∼79 kDa) enzymes belong to a family of large-subunit catalases, constituting a unique fungal and bacterial group. The catC gene displayed a relatively constant pattern of expression, not being induced by oxidative or other types of stress. Targeted disruption of catC eliminated a constitutive catalase activity not detected previously in zymogram gels. However, a catalase activity detected in catA catBmutant strains during late stationary phase was still present incatC and catABC null mutants, thus demonstrating the presence of a fourth catalase, here named catalase D (CatD). Neither catC nor catABC triple mutants showed any developmental defect, and both mutants grew as well as wild-type strains in H2O2-generating substrates, such as fatty acids, and/or purines as the sole carbon and nitrogen sources, respectively. CatD activity was induced during late stationary phase by glucose starvation, high temperature, and, to a lesser extent, H2O2 treatment. The existence of at least four differentially regulated catalases indicates a large and regulated capability for H2O2detoxification in filamentous fungi.

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Shin, Dong-Ho, Young-Seok Choi et You-Hee Cho. « Unusual Properties of Catalase A (KatA) of Pseudomonas aeruginosa PA14 Are Associated with Its Biofilm Peroxide Resistance ». Journal of Bacteriology 190, n^o 8 (28 décembre 2007) : 2663–70. http://dx.doi.org/10.1128/jb.01580-07.

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ABSTRACT Pseudomonas aeruginosa is a ubiquitous environmental bacterium whose major catalase (KatA) is highly stable, extracellularly present, and required for full virulence as well as for peroxide resistance in planktonic and biofilm states. Here, we dismantled the function of P. aeruginosa KatA (KatAPa) by comparing its properties with those of two evolutionarily related (clade 3 monofunctional) catalases from Bacillus subtilis (KatABs) and Streptomyces coelicolor (CatASc). We switched the coding region for KatAPa with those for KatABs and CatASc, expressed the catalases under the potential katA-regulatory elements in a P. aeruginosa PA14 katA mutant, and verified their comparable protein levels by Western blot analysis. The activities of KatABs and CatASc, however, were less than 40% of the KatAPa activity, suggestive of the difference in intrinsic catalatic activity or efficiency for posttranslational activity modulation in P. aeruginosa. Furthermore, KatABs and CatASc were relatively susceptible to proteinase K, whereas KatAPa was highly stable upon proteinase K treatment. As well, KatABs and CatASc were undetectable in the extracellular milieu. Nevertheless, katA Bs and catA Sc fully rescued the peroxide sensitivity and osmosensitivity of the katA mutant, respectively. Both catalase genes rescued the attenuated virulence of the katA mutant in mouse acute infection and Drosophila melanogaster models. However, the peroxide susceptibility of the katA mutant in a biofilm growth state was rescued by neither katA Bs nor catA Sc. Based on these results, we propose that the P. aeruginosa KatA is highly stable compared to the two major catalases from gram-positive bacteria and that its unique properties involving metastability and extracellular presence may contribute to the peroxide resistance of P. aeruginosa biofilm and presumably to chronic infections.

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Yumoto, Isao, Daisen Ichihashi, Hideaki Iwata, Anita Istokovics, Nobutoshi Ichise, Hidetoshi Matsuyama, Hidetoshi Okuyama et Kosei Kawasaki. « Purification and Characterization of a Catalase from the Facultatively Psychrophilic Bacterium Vibrio rumoiensis S-1T Exhibiting High Catalase Activity ». Journal of Bacteriology 182, n^o 7 (1 avril 2000) : 1903–9. http://dx.doi.org/10.1128/jb.182.7.1903-1909.2000.

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ABSTRACT Catalase from the facultatively psychrophilic bacteriumVibrio rumoiensis S-1T, which was isolated from an environment exposed to H2O2 and exhibited high catalase activity, was purified and characterized, and its localization in the cell was determined. Its molecular mass was 230 kDa, and the molecule consisted of four identical subunits. The enzyme, which was not apparently reduced by dithionite, showed a Soret peak at 406 nm in a resting state. The catalytic activity was 527,500 U · mg of protein−1 under standard reaction conditions at 40°C, 1.5 and 4.3 times faster, respectively, than those of theMicrococcus luteus and bovine catalases examined under the same reaction conditions, and showed a broad optimum pH range (pH 6 to 10). The catalase from strain S-1T is located not only in the cytoplasmic space but also in the periplasmic space. There is little difference in the activation energy for the activity between strain S-1T catalase and M. luteus and bovine liver catalases. The thermoinstability of the activity of the former catalase were significantly higher than those of the latter catalases. The thermoinstability suggests that the catalase from strain S-1T should be categorized as a psychrophilic enzyme. Although the catalase from strain S-1T is classified as a mammal type catalase, it exhibits the unique enzymatic properties of high intensity of enzymatic activity and thermoinstability. The results obtained suggest that these unique properties of the enzyme are in accordance with the environmental conditions under which the microorganism lives.

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Fu, Xinhua, Wei Wang, Jianhua Hao, Xianglin Zhu et Mi Sun. « Purification and Characterization of Catalase from Marine BacteriumAcinetobactersp. YS0810 ». BioMed Research International 2014 (2014) : 1–7. http://dx.doi.org/10.1155/2014/409626.

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The catalase from marine bacteriumAcinetobactersp. YS0810 (YS0810CAT) was purified and characterized. Consecutive steps were used to achieve the purified enzyme as follows: ethanol precipitation, DEAE Sepharose ion exchange, Superdex 200 gel filtration, and Resource Q ion exchange. The active enzyme consisted of four identical subunits of 57.256 kDa. It showed a Soret peak at 405 nm, indicating the presence of iron protoporphyrin IX. The catalase was not apparently reduced by sodium dithionite but was inhibited by 3-amino-1,2,4-triazole, hydroxylamine hydrochloride, and sodium azide. Peroxidase-like activity was not found with the substrate o-phenylenediamine. So the catalase was determined to be a monofunctional catalase. N-terminal amino acid of the catalase analysis gave the sequence SQDPKKCPVTHLTTE, which showed high degree of homology with those of known catalases from bacteria. The analysis of amino acid sequence of the purified catalase by matrix-assisted laser desorption ionization time-of-flight mass spectrometry showed that it was a new catalase, in spite of its high homology with those of known catalases from other bacteria. The catalase showed high alkali stability and thermostability.

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Arabaci, G., et A. Usluoglu. « Catalytic Properties and Immobilization Studies of Catalase fromMalva sylvestrisL. » Journal of Chemistry 2013 (2013) : 1–6. http://dx.doi.org/10.1155/2013/686185.

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Catalase was partially purified fromMalva sylvestrisL. and immobilized onto chitosan. Then, its catalytic properties were investigated. (NH4)2SO4precipitation and dialysis were performed in the extracted enzyme. Further purification was performed with sephadex G-200 column. Kinetic studies of the purified enzyme activity were measured and characterized. The inhibitory effects of KCN, NaN3, CuSO4, and EDTA onM. sylvestrisL. catalase activity were observed except NaCl. Furthermore,M. sylvestrisL. catalase was immobilized covalently with glutaraldehyde onto chitosan particles. The pH and temperature optima as well as the changes in the kinetics (Km, Vmax) of the immobilized and freeM. sylvestrisL. catalase were determined. The Km value for immobilized catalase (23.4 mM) was higher than that of free enzyme (17.6 mM). Optimum temperature was observed higher than that of the free enzyme. The optimum pH was the same for both free and immobilized catalases (pH 7.50). Immobilized catalase showed higher storage and thermal stabilities than free catalases. Free catalase lost all its activity within 60 days whereas immobilized catalase lost 45% of its activity during the same incubation period at 4°C. The remaining immobilized catalase activity was about 70% after 8 cycles of batch operations.

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Compagna, Anna Maria, et Núria Puigdevall. « Studi di catalanistica in Italia (2005-2014 circa) ». SCRIPTA. Revista Internacional de Literatura i Cultura Medieval i Moderna 5, n^o 5 (12 juin 2015) : 162. http://dx.doi.org/10.7203/scripta.5.6383.

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Riassunto: In questo articolo si offre un panorama degli studi catalani che si svolgono in Italia partendo dalla segnalazione ragionata dei più recenti contributi offerti dalla RISCAT, rivista dell’Associazione Italiana di Studi Catalani.Parole chiave: catalanistica italiana, studi catalani in Italia, RISCAT, AISCAbstract: This article provides an overview of Catalan studies carried out in Italy, based on the recent contribution offered in the RISCAT, journal of the Catalan Studies Italian Association.Keywords: Italian Catalanistic, Catalan Studies in Italy, RISCAT, AISC

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Chouchane, Salem, Istvan Lippai et Richard S. Magliozzo. « Catalase-Peroxidase (Mycobacterium tuberculosisKatG) Catalysis and Isoniazid Activation† ». Biochemistry 39, n^o 32 (août 2000) : 9975–83. http://dx.doi.org/10.1021/bi0005815.

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Vassilyadi, Michael, et Frederick Archibald. « Catalase, superoxide dismutase, and the production of O2-sensitive mutants of Bacillus coagulans ». Canadian Journal of Microbiology 31, n^o 11 (1 novembre 1985) : 994–99. http://dx.doi.org/10.1139/m85-188.

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A number of facultatively anaerobic members of the genus Bacillus were screened for their catalase, diaminobenzidine peroxidase, and superoxide dismutase activities. A strain of Bacillus coagulans (7050) lacking peroxidatic activity and containing single catalatic and superoxide dismutase activities was selected. Responses of the superoxide dismutase activity and catalase level to the partial pressure of oxygen, and Fe and Mn levels, as well as to aerobic and fermentative metabolism, were determined. There appeared to be a relationship between high endogenous catalase levels and the high H2O2 evolution and KCN insensitivity of B. coagulans respiration. Bacillus coagulans 7050 was mutagenized with N-methyl-N′-nitro-N-nitrosoguanidine and screened for the expression of oxygen intolerance. All of the 38 stable oxygen sensitive mutants obtained had very low or completely absent catalatic activity and catalase protein. No mutant lacked superoxide dismutase, although five showed significantly lowered levels of the enzyme. Exogenous bovine liver catalase restored aerotolerance and reduced cell pleomorphism in the mutants.

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Lawer-Yolar, Gideon, Benjamin Dawson-Andoh et Emmanuel Atta-Obeng. « Synthesis of Biodiesel from Tall Oil Fatty Acids by Homogeneous and Heterogeneous Catalysis ». Sustainable Chemistry 2, n^o 1 (10 mars 2021) : 206–21. http://dx.doi.org/10.3390/suschem2010012.

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This study compared the yield of biodiesel produced from tall oil fatty acids (TOFA) via (i) homogeneous catalyst (sulfuric acid) and (ii) a heterogeneous catalyst (Amberlyst® BD20, together with Ambersep BD 19 (Midcontinental Chemical Co., Olathe, KS, USA)® using a batch reactor. The effect of operation conditions including temperature, catalyst concentration, methanol: oil ratio and reaction time on esterification yield were investigated. Gas chromatographic data showed that the major fatty acids present in the TOFA are oleic acid (C18:1n9) and linoleic acid (C18:2n6). Homogenous catalysis yielded 96.76% biodiesel compared to 90.24% for heterogeneous catalysis. Optimized conditions for homogenous catalysis were at a catalyst concentration of 0.5 w/w%, 15:1 methanol: oil mass ratio at 55 °C for 60 min. FTIR results also showed that the homogeneous catalyst yielded a more complete reaction toward biodiesel production in a shorter time (60 min) compared to the heterogeneous catalyst (4.7 h). For heterogeneous catalysis, the highest yield and the lowest acid value were achieved after a second recycling because the reactants were not fully in contact with the catalyst during the first recycling. The catalyst did not show a reduction in catalytic activity even after the fourth recycling. However, the acid value was higher than that for ASTM standards for biodiesel.

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Sigaud, Samuel, Vanessa Becquet, Pierre Frendo, Alain Puppo et Didier Hérouart. « Differential Regulation of Two Divergent Sinorhizobium meliloti Genes for HPII-Like Catalases during Free-Living Growth and Protective Role of Both Catalases during Symbiosis ». Journal of Bacteriology 181, n^o 8 (15 avril 1999) : 2634–39. http://dx.doi.org/10.1128/jb.181.8.2634-2639.1999.

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ABSTRACT Two catalases, KatA and KatB, have been detected inSinorhizobium meliloti growing on rich medium. Here we characterize a new catalase gene encoding a third catalase (KatC). KatC activity was detectable only at the end of the stationary phase inS. meliloti growing in minimum medium, whereas KatA activity was found during the exponential phase. Analysis with akatC-lacZ fusion demonstrated that katCexpression is mainly regulated at the transcription level. An increase of catalase activity correlating with KatA induction was detected in bacteroids. A dramatic decrease of nitrogen fixation capacity in a katA katC double mutant was observed, suggesting that these catalases are very important for the protection of the nitrogen fixation process.

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Burnat, Dariusz, Roman Kontic, Lorenz Holzer, Patrick Steiger, Davide Ferri et Andre Heel. « Smart material concept : reversible microstructural self-regeneration for catalytic applications ». Journal of Materials Chemistry A 4, n^o 30 (2016) : 11939–48. http://dx.doi.org/10.1039/c6ta03417a.

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This paper presents a proof-of-concept study and demonstrates the next generation of a “smart” catalyst material, applicable to high temperature catalysis and electro-catalysis such as gas processing and as a catalyst for solid oxide cells.

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Schliebs, Wolfgang, Christian Würtz, Wolf-Hubert Kunau, Marten Veenhuis et Hanspeter Rottensteiner. « A Eukaryote without Catalase-Containing Microbodies : Neurospora crassa Exhibits a Unique Cellular Distribution of Its Four Catalases ». Eukaryotic Cell 5, n^o 9 (septembre 2006) : 1490–502. http://dx.doi.org/10.1128/ec.00113-06.

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ABSTRACT Microbodies usually house catalase to decompose hydrogen peroxide generated within the organelle by the action of various oxidases. Here we have analyzed whether peroxisomes (i.e., catalase-containing microbodies) exist in Neurospora crassa. Three distinct catalase isoforms were identified by native catalase activity gels under various peroxisome-inducing conditions. Subcellular fractionation by density gradient centrifugation revealed that most of the spectrophotometrically measured activity was present in the light upper fractions, with an additional small peak coinciding with the peak fractions of HEX-1, the marker protein for Woronin bodies, a compartment related to the microbody family. However, neither in-gel assays nor monospecific antibodies generated against the three purified catalases detected the enzymes in any dense organellar fraction. Furthermore, staining of an N. crassa wild-type strain with 3,3′-diaminobenzidine and H2O2 did not lead to catalase-dependent reaction products within microbodies. Nonetheless, N. crassa does possess a gene (cat-4) whose product is most similar to the peroxisomal type of monofunctional catalases. This novel protein indeed exhibited catalase activity, but was not localized to microbodies either. We conclude that N. crassa lacks catalase-containing peroxisomes, a characteristic that is probably restricted to a few filamentous fungi that produce little hydrogen peroxide within microbodies.

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Jin, Jia Min. « Catalysis Mechanism and Application of Carbon Gasification Reaction-A Comparison of Two Heterogeneous Catalysis Mechanisms ». International Journal of Chemistry 14, n^o 1 (14 avril 2022) : 23. http://dx.doi.org/10.5539/ijc.v14n1p23.

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This article is a brief summary article of research. The results of the three times experiments are reviewed. two heterogeneous catalysis mechanisms are introduced, namely: Chemical Reaction Mode Cyclic Catalysis Mechanism-CRM and Electron Cyclic Donate-Accept Catalysis Mechanism-ECDAM or Electron Orbital Deformation-Recovery Cyclic Catalysis Mechanism -EODRM. Some difficulties encountered by CRM are listed. The author clearly points out that the CRM is not credible. This false theory has misled us for more than 100 years. About ECDAM, the article also gives a brief description. The main point of ECDAM is that the catalysis phenomenon are physical rather than chemical phenomenon. The catalysts do not participate in chemical reactions. It's just contact, electron cyclic donate-accept or electron orbital deformation-recovery cycle. The theory contains three viewpoints: 1. There is a boundary between the catalyst and the poison. 2. The active of the catalyst or the degree of toxicity of the poison is closely related to ihe electronegative value of the catalyst or poison. 3. The active of catalyst is closely related to the chemical state of the catalyst The selectivity of catalyst is also related to electronegative or energy level According to ECDAM, the author considers that there are several problems worth studying in production and scientific research. such as: alumina is a poison in the Fe ammonia synthesis catalyst. The Cordierite (2MgO·2Al2O3·5SiO2) ceramic honeycomb support is also a poison in automotive exhaust purification catalyst. The Cordierite ceramic honeycomb is retardant in wall flow filter for diesel vehicles. Activated carbon is a poison in the Ruthenium catalyst for ammonia synthesis. Alumina and activated carbon all are a poison to noble metal catalysts, and so on.

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Hansberg, Wilhelm, Teresa Nava-Ramírez, Pablo Rangel-Silva, Adelaida Díaz-Vilchis et Aydé Mendoza-Oliva. « Large-Size Subunit Catalases Are Chimeric Proteins : A H2O2 Selecting Domain with Catalase Activity Fused to a Hsp31-Derived Domain Conferring Protein Stability and Chaperone Activity ». Antioxidants 11, n^o 5 (17 mai 2022) : 979. http://dx.doi.org/10.3390/antiox11050979.

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Bacterial and fungal large-size subunit catalases (LSCs) are like small-size subunit catalases (SSCs) but have an additional C-terminal domain (CT). The catalytic domain is conserved at both primary sequence and structural levels and its amino acid composition is optimized to select H2O2 over water. The CT is structurally conserved, has an amino acid composition similar to very stable proteins, confers high stability to LSCs, and has independent molecular chaperone activity. While heat and denaturing agents increased Neurospora crassa catalase-1 (CAT-1) activity, a CAT-1 version lacking the CT (C63) was no longer activated by these agents. The addition of catalase-3 (CAT-3) CT to the CAT-1 or CAT-3 catalase domains prevented their heat denaturation in vitro. Protein structural alignments indicated CT similarity with members of the DJ-1/PfpI superfamily and the CT dimers present in LSCs constitute a new type of symmetric dimer within this superfamily. However, only the bacterial Hsp31 proteins show sequence similarity to the bacterial and fungal catalase mobile coil (MC) and are phylogenetically related to MC_CT sequences. LSCs might have originated by fusion of SSC and Hsp31 encoding genes during early bacterial diversification, conferring at the same time great stability and molecular chaperone activity to the novel catalases.

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Pounder, J. I., et A. J. Anderson. « Catalase released from beneficial and plant-pathogenic pseudomonads by water and chloroform treatments ». Canadian Journal of Microbiology 40, n^o 8 (1 août 1994) : 630–36. http://dx.doi.org/10.1139/m94-100.

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Survival of pseudomonads during plant colonization may involve bacterial catalases to degrade the hydrogen peroxide produced by the plant. The specific activities of catalases in lysates from two saprophytic isolates of Pseudomonas putida and Pseudomonas fluorescens and three races of Pseudomonas syringae pv. glycinea were similar. To explore the location of the bacterial catalases, cells of the pathogenic and saprophytic pseudomonads were treated with chloroform, which is reported to release periplasmic proteins. Although catalase was released by chloroform treatment, the cytoplasmic enzymes isocitrate dehydrogenase, superoxide dismutase, and glucose-6-phosphate dehydrogenase were also detected. These proteins may have come from lysis of a small proportion of the cells rather than the periplasm. Water treatment of cells also released amounts of protein similar to those derived from chloroform treatment. Similar responses were found from both pathogenic and saprophytic strains. The release of catalase and proteins from the leaf pathogen P. syringae pv. glycinea race 0 and the root-associated saprophyte P. putida decreased as the cultures aged. With P. putida and P. syringae pv. glycinea race 0, the single isozyme of catalase released by water and chloroform treatment also was detected in lysates. Additional catalase isozymes were present in lysates as the cultures aged.Key words: periplasmic proteins, survival.

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Voitko, K. V., O. M. Bakalinska, Yu V. Goshovska, Yu I. Sementsov et M. T. Kartel. « Catalase-like properties of multilayer graphene oxides and their modified forms ». Surface 12(27) (30 décembre 2020) : 251–62. http://dx.doi.org/10.15407/surface.2020.12.251.

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The catalytic system, that mimets catalase enzyme such as “multilayer graphene oxide /peroxide molecule” in aqueous media was investigated. The main factors that influence on catalyst’s effectiveness were determining. The catalytic activity of as-synthesized multilayered graphene oxides, and their modified forms (oxidized and nitrogen doped) were investigated in the decomposition of hydrogen peroxides at room temperature and physiological pHs by measuring the volume of released gases. A phosphate buffer with a pH of 5 to 8 was chosen as the reaction medium. The original and modified samples were characterized using XPS, TPD-MS, Boehm titration analyses. The effect of surface chemistry on the catalytic reaction proceeding has been studied. It was found that catalysis on the graphene plane is determined by the presence of heteroatoms in their structure. The catalytic process takes place in the kinetic zone over the entire accessible surface of the samples. The active sites of the catalysts contain a large amount of both nitrogen and oxygen-containing functional groups. In addition, the surface of graphene oxide is hydrophilic, which enhances the catalytic reaction in an aqueous medium. It has been established that the rate of hydrogen peroxide decomposition by reduced graphene oxide samples is lower than for samples modified with oxygen and nitrogen. The catalase-like activity of graphene increases in alkaline pH up to 7.8. Studies have shown that samples of multilayer graphenes with a high content of functional groups can be an alternative to the catalase enzyme as a catalyst for the decomposition of hydrogen peroxide in physiological solutions.

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Garre, Victoriano, Ulrike Müller et Paul Tudzynski. « Cloning, Characterization, and Targeted Disruption of cpcat1, Coding for an in Planta Secreted Catalase of Claviceps purpurea ». Molecular Plant-Microbe Interactions® 11, n^o 8 (août 1998) : 772–83. http://dx.doi.org/10.1094/mpmi.1998.11.8.772.

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Claviceps purpurea has been shown to secrete catalases in axenic and parasitic culture. In order to determine the importance of these enzymes in the host-parasite interaction, especially their role in overcoming oxidative stress imposed on the pathogen by the plant's defense system, the catR gene from A. niger was used to isolate a putative catalase gene from a genomic library of C. purpurea. cpcat1 consists of an open reading frame of 2,148 bp that is interrupted by five introns. Its derived gene product shows significant homology to fungal catalases and contains a putative signal peptide of 19 amino acids and three putative N-glycosylation sites, which indicates that CPCAT1 is a secreted catalase. Disruption of the gene by a gene replacement approach resulted in the loss of two catalase isoforms, CATC and CATD, strongly suggesting that they are both encoded by cpcat1. CATD is the major secreted catalase of C. purpurea and is furthermore the only catalase present in the honeydew of infected rye ears. Deletion mutants of cpcat1 were inoculated on rye plants and showed no significant reduction in virulence. Ovarian tissue and honeydew of plants inoculated with the mutants lacked CATD, confirming that this catalase is not essential for colonization of the host tissue by C. purpurea.

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Obis Monné, Aina. « Institut d'Estudis Catalans (2019). Gramàtica bàsica i d'ús de la llengua catalana. Institut d'Estudis Catalans ». RESERCLE. Revista de la Societat d'Ensenyament i Recerca del català com a llengua estrangera 1, n^o 1 (4 décembre 2020) : 120–21. http://dx.doi.org/10.31009/resercle.2020.i1.13.

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Zhang, Shan, Cheng Li, Haihua Ren, Tong Zhao, Qi Li, Shufen Wang, Yanfeng Zhang, Fangming Xiao et Xiaofeng Wang. « BAK1 Mediates Light Intensity to Phosphorylate and Activate Catalases to Regulate Plant Growth and Development ». International Journal of Molecular Sciences 21, n^o 4 (20 février 2020) : 1437. http://dx.doi.org/10.3390/ijms21041437.

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BAK1 (brassinosteroid-insensitive 1 (BRI1) associated receptor kinase 1) plays major roles in multiple signaling pathways as a coreceptor to regulate plant growth and development and stress response. However, the role of BAK1 in high light signaling is still poorly understood. Here we observed that overexpression of BAK1 in Arabidopsis interferes with the function of high light in promoting plant growth and development, which is independent of the brassinosteroid (BR) signaling pathway. Further investigation shows that high light enhances the phosphorylation of BAK1 and catalase activity, thereby reducing hydrogen peroxide (H2O2) accumulation. Catalase3 (CAT3) is identified as a BAK1-interacting protein by affinity purification and LC-MS/MS analysis. Biochemical analysis confirms that BAK1 interacts with and phosphorylates all three catalases (CAT1, CAT2, and CAT3) of the Arabidopsis genome, and the trans-phosphorylation sites of three catalases with BAK1-CD are identified by LC-MS/MS in vitro. Genetic analyses reveal that the BAK1 overexpression plants knocked out all the three CAT genes completely abolishing the effect of BAK1 on suppression of high light-promoted growth. This study first unravels the role of BAK1 in mediating high light-triggered activation of CATs, thereby degrading H2O2 and regulating plant growth and development in Arabidopsis.

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Constantinos G, Vayenas. « Electrochemical promotion of catalysis ». Annals of Advances in Chemistry 6, n^o 1 (8 septembre 2022) : 048–50. http://dx.doi.org/10.29328/journal.aac.1001031.

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The Electrochemical Promotion of Catalysis (EPOC) or Non-Faradaic Electrochemical Promotion of Catalysis (NEMCA effect) is a phenomenon observed as a reversible change in catalytic rate (i.e. no net charge transfer rate) of a chemical reaction occurring on a catalyst film (or supported dispersed catalyst) deposited on an ionically conducting or mixed electronically-ionically conducting solid electrolyte support upon the application of an electrical potential between the catalyst and a second conductive film deposited on the solid electrolyte support.

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Li, Yudong, Michael Hinshelwood et Gottlieb S. Oehrlein. « Investigation of Ni catalyst activation during plasma-assisted methane oxidation ». Journal of Physics D : Applied Physics 55, n^o 15 (19 janvier 2022) : 155202. http://dx.doi.org/10.1088/1361-6463/ac4724.

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Abstract Atmospheric pressure plasma has shown promise in improving thermally activated catalytic reactions through a process termed plasma-catalysis synergy. In this work, we investigated atmospheric pressure plasma jet (APPJ)-assisted CH4 oxidation over a Ni/SiO2 .Al2O3 catalyst. Downstream gas-phase products from CH4 conversion were quantified by Fourier transform infrared spectroscopy. The catalyst near-surface region was characterized by in-situ diffuse reflectance infrared Fourier transform spectroscopy. The catalyst was observed to be activated at elevated temperature (500 °C) if it was exposed to the APPJ operated at large plasma power. ‘Catalyst activation’ signifies that the purely thermal conversion of CH4 using catalysts which had been pre-exposed to plasma became more intense and produced consistently CO product, even if the plasma was extinguished. Without the application of the APPJ to the Ni catalyst surface this was not observed at 500 °C. The study of different exposure conditions of the activated catalyst indicates that the reduction of the catalyst by the APPJ is likely the cause of the catalyst activation. We also observed a systematic shift of the vibrational frequency of adsorbed CO on Ni catalyst when plasma operating conditions and catalyst temperatures were varied and discussed possible explanations for the observed changes. This work provides insights into the plasma-catalyst interaction, especially catalyst modification in the plasma catalysis process, and potentially demonstrates the possibility of utilizing the surface CO as a local probe to understand the plasma-catalyst interaction and shed light on the complexity of plasma catalysis.

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Otsuka, Yuta, Yuto Shimazaki, Hitoshi Nagaoka, Keiji Maruoka et Takuya Hashimoto. « Scalable Synthesis of a Chiral Selenium π-Acid Catalyst and Its Use in Enantioselective Iminolactonization of β,γ-Unsaturated Amides ». Synlett 30, n^o 14 (28 juin 2019) : 1679–82. http://dx.doi.org/10.1055/s-0039-1690109.

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Chiral selenium π-acid catalysis has for a long time been lagging behind other areas of asymmetric catalysis due to a lack of highly enantioselective catalysts. In this regard, we recently developed the first chiral selenium π-acid catalyst which performs the oxidative cyclization of β,γ-unsaturated carboxylic acids with high enantioselectivities. We report herein our improved synthesis of this chiral selenium catalyst, which allows access to a large quantity of the catalyst as the diselenide. In addition, the catalyst is tested in the oxidative cyclization of N-methoxy β,γ-unsaturated amides to give iminolactones with high enantioselectivities.

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Yu, Cuiping, Weilong Wu, Min Gao et Yu Liu. « Modified Cellulose with BINAP-Supported Rh as an Efficient Heterogeneous Catalyst for Asymmetric Hydrogenation ». Catalysts 12, n^o 1 (12 janvier 2022) : 83. http://dx.doi.org/10.3390/catal12010083.

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Asymmetric catalysis is the preferred method for the synthesis of pure chiral molecules in the fine chemical industry. Cellulose has long been sought as a support in enantioselective catalysis. Dialdehyde cellulose (DAC) is produced by the selective oxidation of cellulose and is used to bind 5,5′-diamino Binap by forming a Schiff base. Here, we report the synthesis of modified cellulose-supported Rh as a novel biomass-supported catalyst and the characterization of its morphology, composition, and thermal stability. DAC-BINAP-Rh was a very effective catalyst in the asymmetric hydrogenation of enamides and could be easily recycled. This work provides a novel supported catalyst that broadens the applications of cellulose in asymmetric catalysis.

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Guo, Ming, Anna Block, Crystal D. Bryan, Donald F. Becker et James R. Alfano. « Pseudomonas syringae Catalases Are Collectively Required for Plant Pathogenesis ». Journal of Bacteriology 194, n^o 18 (13 juillet 2012) : 5054–64. http://dx.doi.org/10.1128/jb.00999-12.

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ABSTRACTThe bacterial pathogenPseudomonas syringaepv. tomato DC3000 must detoxify plant-produced hydrogen peroxide (H2O2) in order to survive in its host plant. Candidate enzymes for this detoxification include the monofunctional catalases KatB and KatE and the bifunctional catalase-peroxidase KatG of DC3000. This study shows that KatG is the major housekeeping catalase of DC3000 and provides protection against menadione-generated endogenous H2O2. In contrast, KatB rapidly and substantially accumulates in response to exogenous H2O2. Furthermore, KatB and KatG have nonredundant roles in detoxifying exogenous H2O2and are required for full virulence of DC3000 inArabidopsis thaliana. Therefore, the nonredundant ability of KatB and KatG to detoxify plant-produced H2O2is essential for the bacteria to survive in plants. Indeed, a DC3000 catalase triple mutant is severely compromised in its ability to growin planta, and its growth can be partially rescued by the expression ofkatB,katE, orkatG. Interestingly, our data demonstrate that although KatB and KatG are the major catalases involved in the virulence of DC3000, KatE can also provide some protectionin planta. Thus, our results indicate that these catalases are virulence factors for DC3000 and are collectively required for pathogenesis.

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Zhuang, Huimin, Bili Chen, Wenjin Cai, Yanyan Xi, Tianxu Ye, Chuangye Wang et Xufeng Lin. « UiO-66-supported Fe catalyst : a vapour deposition preparation method and its superior catalytic performance for removal of organic pollutants in water ». Royal Society Open Science 6, n^o 4 (avril 2019) : 182047. http://dx.doi.org/10.1098/rsos.182047.

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A vapour deposition (VD) method was established for preparation of the UiO-66-supported Fe (Fe/UiO-66) catalyst, which provided the first case of the metal-organic framework (MOF)-supported Fe catalyst prepared by using the vapour-based method. The Fe loading was around 7.0–8.5 wt% under the present preparation conditions. The crystal structure of UiO-66 was not obviously influenced by the Fe loading, while the surface area significantly decreased, implicating most of the Fe components resided in the pores on UiO-66. The results for the methyl orange (MO) removal tests showed that MO in aqueous solution can be removed by UiO-66 by adsorption, and in contrast, it can be oxidized by H 2 O 2 with the catalysis of Fe/UiO-66. Further catalytic tests showed that Fe/UiO-66 was rather effective to catalyse the oxidation of benzene derivatives like aniline in water in terms of chemical oxygen demand (COD) removal efficiency. The catalytic test results for Fe/UiO-66 were compared to those of Fe/Al 2 O 3 with the same Fe loading and to the catalysts reported in the literature. This paper provides a general strategy for VD preparation of MOF-supported Fe catalyst on the one hand, and new catalysts for removing organic pollutants from water, on the other hand.

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Lomic, Gizela, Erne Kis, Goran Boskovic et Radmila Marinkovic-Neducin. « Application of scanning electron microscopy in catalysis ». Acta Periodica Technologica, n^o 35 (2004) : 67–77. http://dx.doi.org/10.2298/apt0435067l.

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A short survey of various information obtained by scanning electron microscopy (SEM) in the investigation of heterogeneous catalysts and nano-structured materials have been presented. The capabilities of SEM analysis and its application in testing catalysts in different fields of heterogeneous catalysis are illustrated. The results encompass the proper way of catalyst preparation, the mechanism of catalyst active sites formation catalysts changes and catalyst degradation during their application in different chemical processes. Presented SEM pictures have been taken on a SEM JOEL ISM 35 over 25 years of studies in the field of heterogeneous catalysis.

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Hsueh, C. L., Y. H. Huang, C. C. Wang et C. Y. Chen. « Photooxidation of azo dye Reactive Black 5 using a novel supported iron oxide : heterogeneous and homogeneous approach ». Water Science and Technology 53, n^o 6 (1 mars 2006) : 195–201. http://dx.doi.org/10.2166/wst.2006.197.

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Photooxidation of azo dye Reactive Black 5 (RB5) by H2O2 was performed with a novel supported iron oxide in a batch reactor in the range of pH 2.5–6.0. The iron oxide was prepared through a fluidized-bed reactor (FBR) and much cheaper than the Nafion-based catalysts. Experimental results indicate that the iron oxide can significantly accelerate the degradation of RB5 under the irradiation of UVA light (λ=365 nm). An advantage of the catalyst is its long-term stability, which was confirmed through using the catalyst for multiple runs in the degradation of RB5. In addition, this study focused mainly on determining the proportions of homogeneous catalysis and heterogeneous catalysis in the batch reactor. Conclusively, although heterogeneous catalysis contributes primarily to the oxidation of RB5 during pH 4.5-6.0, the homogeneous catalysis is of increasing importance below pH 4.0 because of the Fe ions leaching from the catalyst to solution.

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Hernàndez i Garcia, Xavier. « Montserrat Corretger & ; Oriol Teixell (eds.), «Literatura catalana contemporània : patrimoni i identitat», Barcelona, Institut d’Estudis Catalans / Universitat Rovira i Virgili, 2019, 251 p. // Josep Camps Arbós & ; Maria Dasca (eds.), «La narrativa catalana al segle XXI, balanç crític», Barcelona, Institut d’Estudis Catalans, 2019, 139 p. » Caplletra. Revista Internacional de Filologia, n^o 71 (6 octobre 2021) : 271. http://dx.doi.org/10.7203/caplletra.71.21043.

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Ressenyes sobre els llibres següents: Montserrat Corretger & Oriol Teixell (eds.), Literatura catalana contemporània: patrimoni i identitat, Barcelona, Institut d’Estudis Catalans / Universitat Rovira i Virgili, 2019, 251 p., ISBN: 978-84-9965-456-0. Josep Camps Arbós & Maria Dasca (eds.), La narrativa catalana al segle xxi, balanç crític, Barcelona, Institut d’Estudis Catalans, 2019, 139 p., ISBN: 978-84-9965-464-5.

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Robbertse, Barbara, O. C. Yoder, Anita Nguyen, Conrad L. Schoch et B. Gillian Turgeon. « Deletion of all Cochliobolus heterostrophus Monofunctional Catalase-Encoding Genes Reveals a Role for One in Sensitivity to Oxidative Stress but None with a Role in Virulence ». Molecular Plant-Microbe Interactions® 16, n^o 11 (novembre 2003) : 1013–21. http://dx.doi.org/10.1094/mpmi.2003.16.11.1013.

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The genome of the maize pathogen Cochliobolus heterostrophus encodes three unlinked monofunctional catalase-encoding (CAT) genes that singly or in combination could offer protection against the harmful effects of oxidative stress. Phylogenetic analysis placed the CAT2 and CAT3 proteins in a cluster with large subunit catalases (CAT3 has a secretory signal sequence and was grouped with known secreted catalases), whereas CAT1 clustered with small subunit catalases. Single, double, and triple cat mutants were created and screened for sensitivity to hydrogen peroxide and altered virulence on maize. All mutants deficient in CAT3 had enhanced sensitivity to hydrogen peroxide, as compared with wild type or with mutants deficient in CAT1, CAT2, or both. All catalase-deficient mutants had normal virulence to maize. Thus, the secreted CAT3 protein protects the fungus from oxidative stress during vegetative growth, but members of this enzyme family, alone or in combination, are not essential for virulence.

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Loewen, Peter C., et Jacek Switala. « Purification and characterization of spore-specific catalase-2 from Bacillus subtilis ». Biochemistry and Cell Biology 66, n^o 7 (1 juillet 1988) : 707–14. http://dx.doi.org/10.1139/o88-081.

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Catalase-2, the catalase found in spores of Bacillus subtilis, has been purified to homogeneity from a nonsporulating strain. The apparent native molecular weight is 504 000. The enzyme appears to be composed of six identical protomers with a molecular weight of 81 000 each. The amino acid composition is similar to the composition of other catalases. Like most catalases, catalase-2 exhibits a broad pH optimum from pH 4 to pH 12 and is sensitive to cyanide, azide, thiol reagents, and amino triazole. The apparent Km for H2O2 is 78 mM. The enzyme exhibits extreme stability, losing activity only slowly at 93 °C and remaining active in 1% SDS – 7 M urea. The green-colored enzyme exhibits a spectrum like heme d with a Soret absorption at 403 nm and a molar absorptivity consistent with one heme per subunit. The heme cannot be extracted with acetone–HCl or ether, suggesting that it is covalently bound to the protein.

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Hillar, A., P. Nicholls, J. Switala et P. C. Loewen. « NADPH binding and control of catalase compound II formation : comparison of bovine, yeast, and Escherichia coli enzymes ». Biochemical Journal 300, n^o 2 (1 juin 1994) : 531–39. http://dx.doi.org/10.1042/bj3000531.

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1. NADPH binds to bovine catalase and to yeast catalases A and T, but not to Escherichia coli catalase HPII. The association was demonstrated using chromatography and fluorimetry. Bound NADPH fluoresces in a similar way to NADPH in solution. 2. Bound NADPH protects bovine and yeast catalases against forming inactive peroxide compound II either via endogenous reductant action or by ferrocyanide reduction during catalytic activity in the presence of slowly generated peroxide. 3. Bound NADPH reduces neither compound I nor compound II of catalase. It apparently reacts with an intermediate formed during the decay of compound I to compound II; this postulated intermediate is an immediate precursor of stable compound II either when the latter is formed by endogenous reductants or when ferrocyanide is used. It represents therefore a new type of hydrogen donor that is not included in the original classification of Keilin and Nicholls [Keilin, D. and Nicholls, P. (1958) Biochim. Biophys. Acta 29, 302-307] 4. A model for NADPH action is presented in which concerted reduction of the ferryl iron and of a neighbouring protein free radical is responsible for the observed NADPH effects. The roles of migrant radical species in mammalian and yeast catalases are compared with similar events in metmyoglobin and cytochrome c peroxidase reactions with peroxides.

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Chen, Jianfeng, Xing Gong, Jianyu Li, Yingkun Li, Jiguo Ma, Chengkang Hou, Guoqing Zhao, Weicheng Yuan et Baoguo Zhao. « Carbonyl catalysis enables a biomimetic asymmetric Mannich reaction ». Science 360, n^o 6396 (28 juin 2018) : 1438–42. http://dx.doi.org/10.1126/science.aat4210.

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Chiral amines are widely used as catalysts in asymmetric synthesis to activate carbonyl groups for α-functionalization. Carbonyl catalysis reverses that strategy by using a carbonyl group to activate a primary amine. Inspired by biological carbonyl catalysis, which is exemplified by reactions of pyridoxal-dependent enzymes, we developed an N-quaternized pyridoxal catalyst for the asymmetric Mannich reaction of glycinate with aryl N-diphenylphosphinyl imines. The catalyst exhibits high activity and stereoselectivity, likely enabled by enzyme-like cooperative bifunctional activation of the substrates. Our work demonstrates the catalytic utility of the pyridoxal moiety in asymmetric catalysis.

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Alyamani, Essam J., Petra Brandt, Jeremy A. Pena, Angela M. Major, James G. Fox, Sebastian Suerbaum et James Versalovic. « Helicobacter hepaticus catalase shares surface-predicted epitopes with mammalian catalases ». Microbiology 153, n^o 4 (1 avril 2007) : 1006–16. http://dx.doi.org/10.1099/mic.0.29184-0.

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Li, Jing, Lu-Shuang Li et Li Xu. « Hierarchically macro/mesoporous silica spheres for catalase immobilization and catalysis ». Materials Letters 193 (avril 2017) : 67–69. http://dx.doi.org/10.1016/j.matlet.2017.01.091.

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Brunelli, Luca, Vladimir Yermilov et Joseph S. Beckman. « Modulation of catalase peroxidatic and catalatic activity by nitric oxide ». Free Radical Biology and Medicine 30, n^o 7 (avril 2001) : 709–14. http://dx.doi.org/10.1016/s0891-5849(00)00512-8.

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Lai, M. E., et A. Bergel. « Electrochemical reduction of oxygen on glassy carbon : catalysis by catalase ». Journal of Electroanalytical Chemistry 494, n^o 1 (décembre 2000) : 30–40. http://dx.doi.org/10.1016/s0022-0728(00)00307-7.

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Neverov, Alexei A., Todd McDonald, Graham Gibson et R. S. Brown. « Catalysis of transesterification reactions by lanthanides Unprecedented acceleration of methanolysis of aryl and alkyl esters promoted by La(OTf)3 at neutral sspH and ambient temperatures ». Canadian Journal of Chemistry 79, n^o 11 (1 novembre 2001) : 1704–10. http://dx.doi.org/10.1139/v01-149.

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La3+ catalysis of the methanolysis of the esters p-nitrophenyl, 2,4-dinitrophenyl, and phenyl acetate (13), phenyl benzoate (4), and ethyl, i-propyl, cyclohexyl, and tert-butyl acetate (5, 6a, 6b, 7) was studied at 25°C as a function of sspH and [La(OTf)3]. The active form of the catalyst is attributed to a dimethoxy-bridged dimer of stoichiometry (La3+)2(OCH3)2, having maximum activity at sspH 8 to 9. For preparative reactions, the active catalyst can be made in situ simply by adding 0.01 equiv of La(OTf)3, and 0.01 equiv of NaOCH3 to a methanol solution containing the ester (1 M). Strong catalysis of methanolysis of both aryl and alkyl esters was observed, although tert-butyl acetate was inert. At sspH 8.5, where the catalyst is maximally active, the transesterification reactions are accelerated by 40 000-fold to 18 000 000-fold in the presence of as little as 5 mM catalyst relative to the background reaction depending on the ester structure. A mechanism for catalysis of transesterification is presented wherein the reactive species is generated by breaking a single LaOCH3 bond of the dimethoxy-bridged dimer to reveal a nucleophilic metal-bound methoxide Lewis acid La3+ electrophilic pair.Key words: lanthanides, transesterification, methanolysis, catalysis, kinetics.

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Shatskiy, Andrey, Reiner Lomoth, Ahmed F. Abdel-Magied, Wangchuk Rabten, Tanja M. Laine, Hong Chen, Junliang Sun et al. « Catalyst–solvent interactions in a dinuclear Ru-based water oxidation catalyst ». Dalton Transactions 45, n^o 47 (2016) : 19024–33. http://dx.doi.org/10.1039/c6dt03789e.

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Jakopitsch, Christa, Anabella Ivancich, Florian Schmuckenschlager, Anuruddhika Wanasinghe, Gerald Pöltl, Paul Georg Furtmüller, Florian Rüker et Christian Obinger. « Influence of the Unusual Covalent Adduct on the Kinetics and Formation of Radical Intermediates in Synechocystis Catalase Peroxidase ». Journal of Biological Chemistry 279, n^o 44 (23 août 2004) : 46082–95. http://dx.doi.org/10.1074/jbc.m408399200.

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Catalase-peroxidases (KatGs) are heme peroxidases with a catalatic activity comparable to monofunctional catalases. They contain an unusual covalent distal side adduct with the side chains of Trp122, Tyr249, and Met275(SynechocysisKatG numbering). The known crystal structures suggest that Tyr249and Met275could be within hydrogen-bonding distance to Arg439. To investigate the role of this peculiar adduct, the variants Y249F, M275I, R439A, and R439N were investigated by electronic absorption, steady-state and transient-state kinetic techniques and EPR spectroscopy combined with deuterium labeling. Exchange of these conserved residues exhibited dramatic consequences on the bifunctional activity of this peroxidase. The turnover numbers of catalase activity of M275I, Y249F, R439A, and R439N are 0.6, 0.17, 4.9, and 3.14% of wild-type activity, respectively. By contrast, the peroxidase activity was unaffected or even enhanced, in particular for the M275I variant. As shown by mass spectrometry and EPR spectra, the KatG typical adduct is intact in both Arg439variants, as is the case of the wild-type enzyme, whereas in the M275I variant the covalent link exists only between Tyr249and Trp122. In the Y249F variant, the link is absent. EPR studies showed that the radical species formed upon reaction of the Y249F and R439A/N variants with peroxoacetic acid are the oxoferryl-porphyrin radical, the tryptophanyl and the tyrosyl radicals, as in the wild-type enzyme. The dramatic loss in catalase activity of the Y249F variant allowed the comparison of the radical species formed with hydrogen peroxide and peroxoacetic acid. The EPR data strongly suggest that the sequence of intermediates formed in the absence of a one electron donor substrate, is por·+→ Trp· (or Trp·+) → Tyr·. The M275I variant did not form the Trp· species because of the dramatic changes on the heme distal side, most probably induced by the repositioning of the remaining Trp122–Tyr249adduct. The results are discussed with respect to the bifunctional activity of catalase-peroxidases.

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