Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:4.2.2.10 (PNL)
341 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Polysaccharide depolymerases and glycoside hydrolases involved in the breakdown of plant structural polysaccharides (hemicellulose and pectins) were monitored in three fractions of the liquid phase of horse caecum digesta: acellular fluid (AF), bacteria (B) and protozoa plus bacteria (PB). 2. Both bacteria and protozoa were found to be involved in the decomposition of pectic substances, with two enzymic activities: depolymerase (polygalacturonase, EC 3.2.1.15; and pectin lyase, EC 4.2.2.10) and esterase (pectinesterase, EC 3.1.1.11). The activity of the PB fraction was higher than that of B. 3. With hemicellulosic substrates, all three fractions showed a significant xylan endo-1,3-beta-xylosidase (EC 3.2.1.32) activity. Mannan was hardly broken down. 4. Galactomannan and arabinogalactan were broken down more extensively by the PB fraction than by the B fraction. Glycosidase activities (xylan 1,4-beta-xylosidase, EC 3.2.1.37 and alpha-L-arabinofuranosidase, EC 3.2.1.55) were also observed.
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PMID:Degradation of hemicellulose and pectin by horse caecum contents. 340 1

A new method for detecting enzymes produced by fungal spores during germination is described here. With this method, the production of enzymes such as protease, cellulase, or pectinase can be correlated with the extent of spore germination. Germination is studied in vitro on agar-based media containing protein, cellulose, or pectin. The spores are immobilized on a permeable membrane mounted on the substrate-containing medium. At various times after inoculation the membrane-bound spores are removed and the medium is stained. The extent of germination is assessed by microscopic examination of the spores and the presence of active hydrolytic enzymes is revealed by the staining. The staining methods are sensitive; detection limits are 1 X 10(-3) unit of cellulase; 2 X 10(-4) unit of protease; 3 X 10(-3) unit of pectin lyase; 3.5 units of polygalacturonase; 2 X 10(-3) unit of pectin methyl esterase. The method has been demonstrated by studying the production of enzymes by germinating conidia of Botrytis cinerea. Cellulase and protease were present before any spores germinated. Pectin lyase was first observed when at least 80% of the spores had germinated. Pectin methyl esterase and polygalacturonase were not produced by the spores.
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PMID:Plate assay for determining the time of production of protease, cellulase, and pectinases by germinating fungal spores. 391 30

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.
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PMID:The faeA genes from Aspergillus niger and Aspergillus tubingensis encode ferulic acid esterases involved in degradation of complex cell wall polysaccharides. 940 81

An extracellular phenolic acid esterase produced by the fungus Penicillium expansum in solid state culture released ferulic and rho-coumaric acid from methyl esters of the acids, and from the phenolic-carbohydrate esters O-[5-O-(trans-feruloyl)-alpha-L-arabinofuranosyl]-(1-->3)-O-beta- D-xylopyranosyl-(1-->4)-D-xylopyranose (FAXX) and O-[5-O-((E)-rho-coumaroyl)-alpha-L-arabinofuranosyl]- (1-->3)-O-beta-D-xylopyranosyl-(1-->4)-D-xylopyranose (PAXX). The esterase was purified 360-fold in successive steps involving ultrafiltration and column chromatography by gel filtration, anion exchange and hydrophobic interaction. These chromatographic methods separated the phenolic acid esterase from alpha-L-arabinofuranosidase, pectate and pectin lyase, polygalacturonase, xylanase and beta-D-xylosidase activities. The phenolic acid esterase had an apparent mass of 65 kDa under non-denaturing conditions and a mass of 57.5 kDa under denaturing conditions. Optimal pH and temperature were 5.6 and 37 degrees C, respectively and the metal ions Cu2+ and Fe3+ at concentrations of 5 mmol 1-1 inhibited feruloyl esterase activity by 95% and 44%, respectively, at the optimum pH and temperature. The apparent Km and Vmax of the purified feruloyl esterase for methyl ferulate at pH 5.6 and 37 degrees C were 2.6 mmol 1-1 and 27.1 mumol min-1 mg-1. The corresponding constants of rho-coumaroyl esterase for methyl coumarate were 2.9 mmol 1-1 and 18.6 mumol min-1 mg-1.
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PMID:Purification and characterization of a feruloyl esterase from the fungus Penicillium expansum. 944 10

Insoluble potato dietary fibre, isolated from potato pulp, can be enzymatically hydrolysed with the pectolytic enzyme preparation Pectinex Ultra SP from Novo Nordisk A/S, in order to produce soluble fibre. The soluble fibre has valuable functional properties for the food industry. Cloned monocomponent enzymes from Pectinex Ultra SP (arabinofuranosidase, endoglucanase II, pectin lyase, polygalacturonase I, rhamnogalacturonan acetyl esterase, rhamnogalacturonase a, rhamnogalacturonase b and xylanase I) were added in order to increase the yield. Surprisingly, however, the yield is not increased when any of the monocomponent enzymes are added. To describe the results a new model designated 'the competitive activity adsorption model' is proposed. The model is based on the fact that the enzymes are adsorbed to the substrate before action. A combination of the Langmuir adsorption isotherm and basic enzyme kinetics shows that different enzymes that adsorb competitively will have an inhibitory effect on each other and consequently decrease the hydrolysis rate and thereby the yield. The model has been confirmed by an experiment in which the fibre has been pre-treated with rhamnogalacturonan acetyl esterase.
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PMID:Enzymatic degradation of plant cell wall polysaccharides: the kinetic effect of competitive adsorption. 1055 96

Most structures of neutral lipases and esterases have been found to adopt the common alpha/beta hydrolase fold and contain a catalytic Ser-His-Asp triad. Some variation occurs in both the overall protein fold and in the location of the catalytic triad, and in some enzymes the role of the aspartate residue is replaced by a main-chain carbonyl oxygen atom. Here, we report the crystal structure of pectin methylesterase that has neither the common alpha/beta hydrolase fold nor the common catalytic triad. The structure of the Erwinia chrysanthemi enzyme was solved by multiple isomorphous replacement and refined at 2.4 A to a conventional crystallographic R-factor of 17.9 % (R(free) 21.1 %). This is the first structure of a pectin methylesterase and reveals the enzyme to comprise a right-handed parallel beta-helix as seen in the pectinolytic enzymes pectate lyase, pectin lyase, polygalacturonase and rhamnogalacturonase, and unlike the alpha/beta hydrolase fold of rhamnogalacturonan acetylesterase with which it shares esterase activity. Pectin methylesterase has no significant sequence similarity with any protein of known structure. Sequence conservation among the pectin methylesterases has been mapped onto the structure and reveals that the active site comprises two aspartate residues and an arginine residue. These proposed catalytic residues, located on the solvent-accessible surface of the parallel beta-helix and in a cleft formed by external loops, are at a location similar to that of the active site and substrate-binding cleft of pectate lyase. The structure of pectin methylesterase is an example of a new family of esterases.
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PMID:Three-dimensional structure of Erwinia chrysanthemi pectin methylesterase reveals a novel esterase active site. 1116 5

The toxicological characteristics of dietary decomposed alder leaf litter against mosquito larvae were further investigated through enzymatic and chemical purification of a phenoliclike cell-wall fraction isolated from crude litter. The toxicity of the subfractions obtained was controlled by standard bioassays on third instars of Aedes aegypti chosen as a reference target species. Enzymatic hydrolyses of the cell-wall fraction were performed with caylase, pectolyase, esterase, and beta-glycosidase, in order to release, respectively, cellulose material and phenolic compounds bound to lignins. These treatments did not affect the larvicidal activity and the phenolic activity of the cell-wall fraction. Chemical alkaline and acid hydrolyses were carried out to break ester and glycosidic bonds of the cell-wall fraction. Comparison of HPLC profiles of the hydrolysates from both toxic and nontoxic fractions did not reveal differences between the phenolic acids released. Aluminum chloride, known for its phenolic complexing activity, counteracted the larvicidal activity of the cell-wall fraction. Altogether, these results suggest the involvement of ligninlike compounds in the toxicity of dietary alder leaf litter against larval mosquitoes. The toxicity of this fraction, which was very sensitive to drastic and smooth oxidations, seemed to be associated with a strong oxidative potential. These results are discussed in relation to a possible mode of action of lignins in the plant-mosquito interactions.
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PMID:Involvement of ligninlike compounds in toxicity of dietary alder leaf litter against mosquito larvae. 1138 61

Eight cold-adapted, polygalacturonase-producing yeasts belonging to four species were isolated from frozen environmental samples in Iceland. They were identified as Cystofilobasidium lari-marini, Cystofilobasidium capitatum, Cryptococcus macerans and Cryptococcus aquaticus species by sequence analysis of rDNA regions. Growth behavior of the isolates was investigated. All strains could grow at 2 degrees C. Addition of glucose to pectin-containing culture medium had a repressive effect on enzyme production except for C. aquaticus, which showed increased polygalacturonase activity. Optimal temperature for enzyme production for the Cystofilobasidium strains was 14 degrees C, while that for the Cryptococcus strains was lower. Among the isolates, C. lari-marini S3B produced highest levels of enzyme activity at pH 3.2. Preliminary characterization of the polygalacturonases in the culture supernatant showed the enzyme from Cystofilobasidium strains to be optimally active at 40 degrees C and pH 5, and that from the Cryptococcus strains at 50 degrees C and pH 4. The polygalacturonase from C. macerans started to lose activity after 1 h of incubation at 40 degrees C, while that from the other strains had already lost activity at 30 degrees C. All the strains except C. aquaticus produced isoenzymes of polyglacturonase. In addition to polygalacturonase, the Cystofilobasidium strains produced pectin lyase, C. aquaticus pectin esterase, and C. macerans pectin lyase, pectate lyase and pectin esterase.
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PMID:Cold-adapted yeasts as producers of cold-active polygalacturonases. 1276 49

The ability of six strains of Pichia anomala, four strains of Pichia kluyveri and two strains of Hanseniaspora uvarum predominant during coffee processing to produce polygalacturonase (PG), pectin esterase (PE) and pectin lyase (PL) in yeast polygalacturonic acid medium (YPA) and in coffee broth (CB) was studied. For comparison, a reference strain of Kluyveromyces marxianus CCT 3172 isolated from cocoa and reported to produce high amount of PG was included. Initial screening of PG activity using YPA medium showed that K. marxianus CCT 3172, P. anomala S16 and P. kluyveri S13Y4 had the strongest activity. Enzymatic assays showed that the four yeast species secreted PG, but none of the yeasts investigated was found to produce PE or PL. P. anomala S16 and P. kluyveri S13Y4 were found to produce higher amounts of PG when grown in CB than in YPA. When K. marxianus CCT 3172, P. anomala S16 and P. kluyveri S13Y4 were grown in YPA broth adjusted to pH of 3.0-8.0 and incubated at temperatures of 15-40 degrees C, the three yeast species secreted the highest amount of PG at pH 6.0 and at 30 degrees C. For PG secreted by K. marxianus CCT 3172 and P. anomala S16, the optimum pH and temperature for the enzymatic activity were 5.5 and 40 degrees C, respectively. On the other hand, PG produced by P. kluyveri S13Y4 showed the highest activity at pH 5.0 and 50 degrees C. Significant differences in the extracellular activity of PG were found between the yeasts species as well as between strains within same species. High amounts of PG were produced by two strains of P. anomala and P. kluyveri. It is therefore likely that strains of those two species may be involved in the degradation of pectin during coffee fermentation.
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PMID:Pectin degrading enzymes in yeasts involved in fermentation of Coffea arabica in East Africa. 1678 90

A total of 48 full-length protein sequences of pectin lyases from different source organisms available in NCBI were subjected to multiple sequence alignment, domain analysis, and phylogenetic tree construction. A phylogenetic tree constructed on the basis of the protein sequences revealed two distinct clusters representing pectin lyases from bacterial and fungal sources. Similarly, the multiple accessions of different source organisms representing bacterial and fungal pectin lyases also formed distinct clusters, showing sequence level homology. The sequence level similarities among different groups of pectinase enzymes, viz. pectin lyase, pectate lyase, polygalacturonase, and pectin esterase, were also analyzed by subjecting a single protein sequence from each group with common source organism to tree construction. Four distinct clusters representing different groups of pectinases with common source organisms were observed, indicating the existing sequence level similarity among them. Multiple sequence alignment of pectin lyase protein sequence of different source organisms along with pectinases with common source organisms revealed a conserved region, indicating homology at sequence level. A conserved domain Pec_Lyase_C was frequently observed in the protein sequences of pectin lyases and pectate lyases, while Glyco_hydro_28 domains and Pectate lyase-like beta-helix clan domain are frequently observed in polygalacturonases and pectin esterases, respectively. The signature amino acid sequence of 41 amino acids, i.e. TYDNAGVLPITVNSNKSLIGEGSKGVIKGKGLRIVSGAKNI, related with the Pec_Lyase_C is frequently observed in pectin lyase protein sequences and might be related with the structure and enzymatic function.
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PMID:In silico analysis of pectin lyase and pectinase sequences. 1991 17


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