Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.15 (pectinase)
 2,440 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Water-soluble and alkaline-soluble crude polysaccharides which were separated from the roots or leaves of Panax ginseng C. A. Meyer, were compared for their anti-ulcer activity. Of these four polysaccharide fractions, the water-soluble crude polysaccharide fraction (GL-2) from the leaves and the alkaline-soluble crude polysaccharide fraction (GRA-2) from the roots prevented HCl/ethanol-induced ulcerogenesis in mice potently. The most potent fraction, GL-2, was further fractionated into four polysaccharide fractions by precipitation with cethyltrimethylammonium bromide, and the weakly acidic polysaccharide fraction, GL-4, showed the most potent inhibition of gastric lesion formation. The activity of GL-4 decreased after treatment with periodate or digestion with endo-polygalacturonase, indicating that the carbohydrate moiety may contribute to the expression of the activity. GL-4 was further purified by anion-exchange chromatography and gel filtration, and the most active purified polysaccharide, GL-4IIb1III was obtained. GL-4IIb1III (average relative molecular mass, 16,000 d) had the nature of a pectic polysaccharide, and was composed mainly of galactose and galacturonic acid with small proportions of rhamnose, arabinose, mannose, glucose, and glucuronic acid. GL-4IIIb1III prevented HCl/ethanol-induced ulcerogenesis in mice dose dependently.
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PMID:Purification of an anti-ulcer polysaccharide from the leaves of Panax ginseng. 147 Jun 69

A water-soluble crude polysaccharide fraction (BR-1) prepared from the root of Bupleurum falcatum L. (Japanese name = Saiko) prevented HCl/ethanol induced ulcerogenesis in mice significantly. BR-1 was fractionated into four polysaccharide fractions (BR-2, BR-3, BR-4, and BR-5) by the addition of cetyltrimethylammonium bromide, and the strongly acidic polysaccharide fraction BR-2 showed the most potent inhibition of gastric lesion formation. When BR-2 was further fractionated by anion-exchange chromatography, the most potent anti-ulcer activity was observed in the pectin-like polysaccharide, bupleuran 2IIc. Bupleuran 2IIc was homogeneous as determined by electrophoresis and gel filtration. Bupleuran 2IIc was composed mainly of galacturonic acid with small proportions of arabinose, rhamnose, and galactose, and its average relative molecular mass was estimated to be 63,000 d. BR-2 lost most of its activity after treatment with periodate or digestion with endo-polygalacturonase indicating that the polygalacturonan region and/or the molecular mass may contribute to activity.
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PMID:Purification of anti-ulcer polysaccharides from the roots of Bupleurum falcatum. 181 48

The mechanism of action for the hydrolysis of polygalacturonic acid by the enzyme endo-polygalacturonase (poly(1,4-alpha-D-galacturonide) glycanohydrolase, EC 3.2.1.15) was investigated. The enzyme from Aspergillus ustus was purified to homogeneity and used for the study. The endo-polygalacturonase had a molecular weight of 36,000 daltons, a pI of 8.3, specific activity of 785 units/mg, Km of 0.82 mg/ml, and Vmax of 976 micromoles of product min-1 mg-1. Amino acids involved in the catalysis were identified by chemical modification and the active site characterized. Inhibition by hydroxynitrobenzyl bromide and diethylpyrocarbonate, followed by substrate protection studies showed that tryptophan and histidine were involved at or near the active site. Kinetic constants of partially inhibited enzyme, suggest the involvement of tryptophan in substrate binding and histidine in catalysis. Quenching of tryptophan fluorescence of the enzyme in the presence of polygalacturonic acid substantiated the conclusion that tryptophan was involved in substrate binding. An isotope effect of 1.8 was observed with deuterated water on the Vmax of the endo-polygalacturonase, with the proton inventory giving a linear relationship. The proposed mechanism involves a single proton transfer from the histidine residue of the enzyme to the glycosidic oxygen and hydrolysis by the addition of a water molecule.
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PMID:Implication of tryptophan and histidine in the active site of endo-polygalacturonase from Aspergillus ustus: elucidation of the reaction mechanism. 881 23

Homogeneous endo-polygalacturonase (PG) was covalently bound to cyanogen-bromide-activated Sepharose, and the resulting PG-Sepharose conjugate was utilized to purify, by affinity chromatography, a protein from Phaseolus vulgaris hypocotyls that binds to and inhibits PG. Isoelectric focusing of the purified PG-inhibiting protein (PGIP) showed a major protein band that coincided with PG-inhibiting activity. PGIP formed a complex with PG at pH 5.0 and at low salt concentrations. The complex dissociated in 0.5 m Na-acetate and pH values lower than 4.5 or higher than 6.0. Formation of the PG-PGIP complex resulted in complete inhibition of PG activity. PG activity was restored upon dissociation of the complex. The protein exhibited inhibitory activity toward PGs from Colletotrichum lindemuthianum, Fusarium moniliforme and Aspergillus niger. The possible role of PGIP in regulating the activity of fungal PG's and their ability to elicit plant defense reactions are discussed.
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PMID:Purification and Characterization of a Polygalacturonase-Inhibiting Protein from Phaseolus vulgaris L. 1666 51