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PubMed1979

Activity of pectinases, amylases, and saccharase in Pythium spp.

The activity of pectine-lyase, polygalacturonase, pectine-methyl-esterase, amylase, and saccharase in Pythium ultimum, Pythium oligandrum, and Pythium debaryanum was determined. Cultures of fungi were cultivated under different temperatures and pH-values within 24 hours and 15 days. The optimum temperature for production of the mentioned enzymes was found to be 24 degrees C. Furthermore, the influence of pH and age of culture on activity of enzyme was investigated. The same trend was found in all the fungus species examined.

Amylases↗
PubMed1999

Sequencing of partially methyl-esterified oligogalacturonates by tandem mass spectrometry and its use to determine pectinase specificities.

Complex mixtures of acidic oligosaccharides were produced by enzymatic digestion of partially methyl-esterified pectin with Aspergillus niger pectin lyase, endopolygalacturonase II, and exopolygalacturonase. To determine the specificities of these pectolytic enzymes toward non-esterified and methyl-esterified galacturonic acid residues, we have studied the methyl esterification patterns of selected oligomers in unseparated pectin digests. Collision-induced dissociation in a nanoelectrospray ionization ion trap mass spectrometer was used to locate methyl-esterified galacturonic acid residues in oligomers up to a degree of polymerization of 10. Analysis of the methyl esterification patterns gave insight into the substrate specificities of these pectolytic enzymes. Isomeric fragment ions containing the reducing and nonreducing ends were differentiated by 18O-labeling of the reducing end.

Carbohydrate Sequence↗
PubMed2003

Isolation and properties of pectinases from the fungus Aspergillus japonicus.

Using anion-exchange chromatography on different carriers and phenyl-Sepharose hydrophobic chromatography, five pectolytic enzymes were isolated from the culture liquid of a mutant strain of Aspergillus japonicus: two endo-polygalacturonases (I and II, 38 and 65 kD, pI 5.6 and 3.3), pectin lyase (50 kD, pI 3.8), and two pectinesterases (I and II) with similar molecular weights (46 and 47 kD) and the same pI (3.8). The pectinesterases apparently represent two isoforms of the same enzyme. All purified enzymes were homogenous according to SDS-PAGE and polyacrylamide gel-IEF, except for endo-polygalacturonase II that gave two bands on isoelectric focusing, but one band on electrophoresis. All enzymes had maximal activity in an acid medium (at pH 4.0-5.5). The pectin lyase and pectinesterase were stable at 40-50 degrees C. The thermal stability of both endo-polygalacturonases was much lower (after 3 h of incubation at 30 degrees C, endo-polygalacturonases I and II lost 40 and 10% of the activity, respectively). The activity of endo-polygalacturonases I and II towards polygalacturonic acid strongly depended on NaCl concentration (optimal concentration of the salt was 0.1-0.2 M); the enzymes were also capable of reducing the viscosity of pectin solution, but rather slowly. The pectin lyase had no activity towards polygalacturonic acid. The activity of the pectin lyase increased with increasing degree of methylation of pectins. Both endo-polygalacturonases demonstrated synergism with the pectinesterase during the hydrolysis of highly methylated pectin. On the contrary, in the mixture of pectin lyase and pectinesterase an antagonism between the two enzymes was observed.

Aspergillus↗
PubMed2003

Polygalacturonase (pectinase), a new oilseed rape allergen.

BACKGROUND: Type I hypersensitivity to rapeseed pollen allergens was described as the result of a cross-sensitization with various pollens that could constitute an aggravating factor in birch or grass pollen allergies. Recently, a few rapeseed pollen allergens were described. The aim of the present work was to identify new rapeseed pollen allergens by using two-dimensional gel analysis, microsequencing, and mass spectrometry. METHODS: Water extractable proteins from oilseed rape pollen or stamen were separated by two-dimensional gel electrophoresis. The proteins were then electroblotted onto a nitrocellulose (NC) sheet. The NC sheets were successively incubated with (1) individual human sera pre-selected for their immunoglobulin E (IgE) reactivity to rapeseed pollen proteins, (2) alkaline phosphatase (AP)-conjugated goat anti-human IgE and (3) AP substrate. The allergens localized by this method were then identified by microsequencing and MALDI-TOF mass spectrometry analysis. RESULTS: Of the 18 sera studied, five recognized a wide multispot zone with a molecular mass around 43 kD and pIs between 6.5 and 8.5. The results obtained with two representative sera are shown. From this zone, two isoforms of the polygalacturonase enzyme were identified by microsequencing. Confirmation was obtained through MALDI-TOF mass spectrometry analysis. CONCLUSION: The present results allow the identification of a new rapeseed allergen that can be the main allergen for some patients.

Allergens↗
PubMed2000

Aeromonas salmonicida subsp. pectinolytica subsp. nov., a new pectinase-positive subspecies isolated from a heavily polluted river.

Aeromonas strains which phenotypically and genetically belong to the Aeromonas salmonicida species but that according to their phenotypic properties constitute a new subspecies have been isolated from the water of a heavily polluted river, the Matanza river, situated near the central district of Buenos Aires city. These strains were ascribed to the A. salmonicida species by using 65 biochemical tests and by DNA-DNA hybridization. They produce acid from -sorbitol, an unusual biochemical property found in a few members of the A. salmonicida species. They also utilize urocanic acid and do not ferment L-rhamnose or utilize LD-lactate, and are elastase- and gluconate-negative. The DNA relatedness was over 70%, the current limit accepted for the phylogenetic definition of a species, to the described A. salmonicida subspecies and nearly 100% within the new group of Aeromonas strains. Phenotypic differentiation from other A. salmonicida subspecies was readily achieved using the following characteristics: growth at 37 degrees C, melanin production, indole and Voges-Proskauer assays, growth on KCN broth, mannitol and sucrose fermentation and gas from glucose. A remarkable property of the strains of the new group was their ability to degrade polypectate, an unusual feature among Aeromonas species in general. The complete 16S rRNA gene of one strain of the new group was sequenced. Comparison with rDNA sequences of Aeromonas members available in databases revealed a close relationship between this strain and strains belonging to A. salmonicida subsp. salmonicida, masoucida and achromogenes, in agreement with the biochemical data. Since the new A. salmonicida strains constitute a tight genomic group that can be identified by phenotypic properties it was concluded that they represent a new subspecies for which the name Aeromonas salmonicida subsp. pectinolytica is proposed. The type strain of A. salmonicida subsp. pectinolytica is 34melT (= DSM 12609T).

Aeromonas↗
PubMed1995

Seeds as natural matrices for immobilization of Aspergillus niger mycelium producing pectinases.

A simple method for the immobilization of Aspergillus niger mycelium producing polygalacturonase (PG) and pectinesterase (PE) is described. Fungal conidia were immobilized on wheat, rye, barley, peas, buckwheat and mustards seeds. Spongy mycelia overgrowing the seed surfaces on mineral medium with pectin produced extracellular PG and PE; the highest production was reached on the wheat carrier. Some of the variables influencing the enzymatic activity have been optimized. After every 24 h, a culture liquid with 6.8-7.8 U of PG ml-1 and 7.0-10.1 U of PE ml-1 was obtained. This procedure also made possible repeated batch enzyme production and, as many as eight subsequent 24-h batches could be fermented by using the same carrier without any loss of PG activity. The addition of sodium orthovanadate (1 mmol) into the medium with pectin caused a significant increase in PG and PE activity produced by free cells of A. niger (by 1.59-fold and 1.67-fold respectively), and only 0.47-fold of PG activity in case of the immobilized mycelium.

Aspergillus niger↗
PubMed1986

Cloning of a Gene Cluster from Cellvibrio mixtus which Codes for Cellulase, Chitinase, Amylase, and Pectinase.

The soil isolate Cellvibrio mixtus UQM2294 degraded a variety of polysaccharides including microcrystalline cellulose. Among 6,000 cosmid clones carrying C. mixtus DNA, constructed in Escherichia coli with pHC79, 50 expressed the ability to degrade one or more of the following substrates: carboxymethyl cellulose, chitin, pectin (polygalacturonic acid), cellobiose, and starch. These degradative genes are encoded in a single 94.1-kilobase segment of the C. mixtus genome; a preliminary order of the genes is starch hydrolysis, esculin hydrolysis, cellobiose utilization, chitin hydrolysis, carboxymethyl cellulose hydrolysis, and polygalacturonic acid hydrolysis. A restriction endonuclease cleavage map was constructed, and the genes for starch, carboxymethyl cellulose, cellobiose, chitin, and pectin hydrolysis were subcloned.

Journal Article↗