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‣ Pectinases: aplicações industriais e perspectivas

Uenojo,Mariana; Pastore,Glaucia Maria
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2007 Português
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18.757816%
Pectic substances are structural heteropolysaccharides that occur in the middle lamellae and primary cell walls of higher plants. They are composed of partially methyl-esterified galacturonic acid residues linked by alpha-1, 4-glycosidic bonds. Pectinolytic enzymes are complex enzymes that degrade pectic polymers and there are several classes of enzymes, which include pectin esterases, pectin and pectate lyases and polygalacturonases. Plants, filamentous fungi, bacteria and yeasts are able to produce pectinases. In the industrial world, pectinases are used in fruit juice clarification, in the production of wine, in the extraction of olive oil, fiber degumming and fermentation of tea, coffee and cocoa.

‣ PaeX, a Second Pectin Acetylesterase of Erwinia chrysanthemi 3937

Shevchik, Vladimir E.; Hugouvieux-Cotte-Pattat, Nicole
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /05/2003 Português
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Erwinia chrysanthemi causes soft-rot diseases of various plants by enzymatic degradation of the pectin in plant cell walls. Pectin is a complex polysaccharide. The main chain is constituted of galacturonate residues, and some of them are modified by methyl and/or acetyl esterification. Esterases are necessary to remove these modifications and, thus, to facilitate the further degradation of the polysaccharidic chain. In addition to PaeY, the first pectin acetylesterase identified in the E. chrysanthemi strain 3937, we showed that this bacterium produces a second pectin acetylesterase encoded by the gene paeX. The paeX open reading frame encodes a 322-residue precursor protein of 34,940 Da, including a 21-amino-acid signal peptide. Analysis of paeX transcription, by using gene fusions, revealed that it is induced by pectic catabolic products and affected by catabolite repression. The expression of paeX is regulated by the repressor KdgR, which controls all the steps of pectin catabolism; by the repressor PecS, which controls most of the pectinase genes; and by catabolite regulatory protein, the global activator of sugar catabolism. The paeX gene is situated in a cluster of genes involved in the catabolism and transport of pectic oligomers. In induced conditions...

‣ The faeA genes from Aspergillus niger and Aspergillus tubingensis encode ferulic acid esterases involved in degradation of complex cell wall polysaccharides.

de Vries, R P; Michelsen, B; Poulsen, C H; Kroon, P A; van den Heuvel, R H; Faulds, C B; Williamson, G; van den Hombergh, J P; Visser, J
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1997 Português
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We report the cloning and characterization of a gene encoding a ferulic acid esterase, faeA, from Aspergillus niger and Aspergillus tubingensis. The A. niger and A. tubingensis genes have a high degree of sequence identity and contain one conserved intron. The gene product, FAEA, was overexpressed in wild-type A. tubingensis and a protease-deficient A. niger mutant. Overexpression of both genes in wild-type A. tubingensis and an A. niger protease-deficient mutant showed that the A. tubingensis gene product is more sensitive to degradation than the equivalent gene product from A. niger. FAEA from A. niger was identical to A. niger FAE-III (C. B. Faulds and G. Williamson, Microbiology 140:779-787, 1994), as assessed by molecular mass, pH and temperature optima, pI, N-terminal sequence, and activity on methyl ferulate. The faeA gene was induced by growth on wheat arabinoxylan and sugar beet pectin, and its gene product (FAEA) released ferulic acid from wheat arabinoxylan. The rate of release was enhanced by the presence of a xylanase. FAEA also hydrolyzed smaller amounts of ferulic acid from sugar beet pectin, but the rate was hardly affected by addition of an endo-pectin lyase.

‣ Cholinesterases from Plant Tissue: V. Cholinesterase Is Not Pectin Esterase 1

Fluck, Richard A.; Jaffe, Mark J.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /11/1974 Português
Relevância na Pesquisa
49.32317%
Several properties of the cholinesterase from Phaseolus aureus Roxb. and of pectin (methyl) esterases from both Phaseolus aureus and Lycopersicon esculentum (L.) Mill. are contrasted. Cholinesterase activity is inhibited by all of the concentrations of NaCl tested, from 0.05 m to 0.9 m, a property which differs sharply from published data pertaining to pectin esterase. Although crude preparations of cholinesterase contain pectin esterase activity, further purification by gel filtration of the cholinesterase results in a nearly complete elimination of the pectin esterase activity. The activity of neither the pectin esterase from Lycopersicon esculentum nor that from Phaseolus aureus is affected by 25 μm neostigmine, a potent inhibitor of the cholinesterase activity extracted from Phaseolus aureus.

‣ Three Feruloyl Esterases in Cellulosilyticum ruminicola H1 Act Synergistically To Hydrolyze Esterified Polysaccharides ▿

Li, Jiabao; Cai, Shichun; Luo, Yuanming; Dong, Xiuzhu
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /09/2011 Português
Relevância na Pesquisa
29.315054%
Feruloyl esterases (Faes) constitute a subclass of carboxyl esterases that specifically hydrolyze the ester linkages between ferulate and polysaccharides in plant cell walls. Until now, the described microbial Faes were mainly from fungi. In this study, we report that Cellulosilyticum ruminicola H1, a previously described fibrolytic rumen bacterium, possesses three different active feruloyl esterases, FaeI, FaeII, and FaeIII. Phylogenetic analysis classified the described bacterial Faes into two types, FaeI and FaeII in type I and FaeIII in type II. Substrate specificity assays indicated that FaeI is more active against the ester bonds in natural hemicelluloses and FaeIII preferentially attacks the ferulate esters with a small moiety, such as methyl groups, while FaeII is active on both types of substrates. Among the three feruloyl esterase genes, faeI was the only one induced significantly by xylose and xylan, while pectin appeared to moderately induce the three genes during the late log phase to stationary phase. Western blot analysis determined that FaeI and FaeIII were secreted and cytoplasmic proteins, respectively, whereas FaeII seemed to be cell associated. The addition of FaeI and FaeII but not FaeIII enhanced the activity of a xylanase on maize cob...

‣ Isolation and Expression analysis of OsPME1, encoding for a putative Pectin Methyl Esterase from Oryza sativa (subsp. indica)

Kanneganti, Vydehi; Gupta, Aditya Kumar
Fonte: Springer-Verlag Publicador: Springer-Verlag
Tipo: Artigo de Revista Científica
Português
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59.51554%
Pectin Methyl Esterases (PMEs) play an essential role during plant development by affecting the mechanical properties of the plant cell walls. Recent studies indicated that PMEs play important role in pollen tube development. In this study, we isolated a 1.3 kb cDNA clone from rice panicle cDNA library. It contained a 1038 bp of open reading frame (ORF) encoding for a putative pectin methyl esterase of 345 aminoacids with a 20 aminoacid signal peptide and was hence designated as OsPME1 (Oryza sativaPectin Methyl Esterase 1). It contained the structural arrangement GXYXE and GXXDFIF, found in the active groups of all PMEs. OsPME1 gene product shared varying identities, ranging from 52 % to 33 % with PMEs from other plant species belonging to Brassicaceae, Fabaceae, Amaranthaceae and Funariaceae. Southern blot analysis indicated that PME1 exists as a single copy in the rice genome. Expression pattern analysis revealed that OsPME1 is expressed only in pollen grains, during the later stages of their development and was also regulated by various abiotic stress treatments and phytohormones. Functional characterization of this pollen specific PME from rice would enable us to understand its role in pollen development.

‣ Inhibition of Pectin Methyl Esterase Activity By Green Tea Catechins

Sagi, Irit; Lewis, Kristin; Tworowski, Dmitry; Shahar, Chen; Selzer, Tzvia
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
80.158613%
Pectin methyl esterases (PMEs) and their endogenous inhibitors are involved in the regulation of many processes in plant physiology, ranging from tissue growth and fruit ripening to parasitic plant haustorial formation and host invasion. Thus, control of PME activity is critical for enhancing our understanding of plant physiological processes and regulation. Here we report on the identification of epigallocatechin gallate (EGCG), a green tea component, as a natural inhibitor for pectin methyl esterases. In a gel assay for PME activity, EGCG blocked esterase activity of pure PME as well as PME extracts from citrus and from parasitic plants. Fluorometric tests were used to determine the IC50 for a synthetic substrate. Molecular docking analysis of PME and EGCG suggests close interaction of EGCG with the catalytic cleft of PME . Inhibition of PME by the green tea compound, EGCG, provides means to study the diverse roles of PMEs in cell wall metabolism and plant development. In addition, this study introduces the use of EGCG as natural product to be used in the food industry and agriculture.; Other Research Unit

‣ Pectin methyl esterases and pectins in normal and hyperhydric shoots of carnation cultured in vitro.

Saher, Shady; Piqueras, Abel; Hellín, Eladio; Olmos, Enrique
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 100864 bytes; application/msword
Português
Relevância na Pesquisa
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5 pages, 2 figures, 2 tables.; Control and hyperhydric micropropagated plantlets from three carnation cultivars have been used to study their pectin composition and the activity of pectin methyl esterases (PMEs; EC 3.1.1.11). Pectins are a highly heterogeneous group of polymers that contribute to cell adhesion, cell wall architecture, and cell wall mechanical strength. Pectins control cell wall porosity and cell wall ionic status and are implicated in intercellular space development. The degree of esterification of pectins is controlled by the activity of cell wall PMEs; their different actions can affect the properties of the cell wall, which have been considered important with respect to controlling the development of hyperhydricity. The total pectins of hyperhydric leaves of the three varieties were significantly reduced in comparison with controls. The pectate fraction was significantly increased in hyperhydric leaves of all varieties while soluble pectins and protopectins were significantly lower. The PME activity of hyperhydric leaves was higher (4–10 times) compared to controls of the three varieties. Isoelectric focusing of PME isozymes revealed the presence of three isoforms; neutral PME activity was the major isozyme in control and hyperhydric leaves of the three varieties...