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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A strain of Bacillus pumilus produced an extracellular pectic enzyme with polygalacturonic acid as the substrate. This enzyme, with optimal activity at pH 8.0 to 8.5, produced reaction products that strongly absorbed light at 232 nm, indicating the presence of a pectic acid trans-eliminase (PATE). Neither pectin esterase nor polygalacturonase was detected in the cell-free culture fluid. Chromatographic examination of the end products revealed the presence of large quantities of unsaturated oligouronides unlike those found with B. polymyxa. It was found that the PATE was produced extracellularly during the negative logarithmic death phase of the organism. The filtrate from sonically treated cells did not show any activity for PATE or hydrolases for lower oligogalacturonides at any time during the growth cycle. The enzyme was inducible. Pectin, National Formulary (NF) was the best inducer, followed by polygalacturonic acid and galacturonic acid. Enzyme activity was markedly stimulated by calcium and other divalent ions. Copper and cobalt ions were inhibitory. The partially purified enzyme showed no significant activity on pectin containing a high methoxyl content (96% esterified). However, pectin NF with a lower methoxyl content (68% esterified) was attacked to a degree by the partially purified and crude enzyme preparations. The initial rate of PATE activity increased up to 60 C, about 16-fold higher than that observed at room temperature. The activation energy was calculated as 12,183 cal/mole. A protective action of calcium chloride against heat inactivation of the PATE was observed. Degradation of polygalacturonic acid by this enzyme produced several unsaturated oligouronides soon after its addition to the substrate. The major endproduct was thought to be different from that of other known PATE enzymes. Paper chromatographic studies and viscosity measurements disclosed the random cleaving nature of the enzyme an endo-PATE.
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PMID:Purification and properties of an polygalacturonic acid trans-eliminase produced by Bacillus pumilus. 512 2

Two polygalacturonase isoenzymes, PG I and PG II, were extracted from Murrieta tomato and purified by gel exclusion and ion-exchange chromatography. The kinetic constants and activation energies of the purified isoenzymes have been determined. Polygalacturonase I has two polypeptide chains (Mr = 47 500 and 41 400) whereas polygalacturonase II is a single polypeptide (Mr = 47 500) as shown by electrophoresis in polyacrylamide gels in the presence of sodium dodecyl sulphate. Both isoenzymes are glycoproteins. Through gas liquid chromatography, polygalacturonase II was shown to contain 4.6% neutral hexoses and 1.5% amino sugars. There are eight D-mannose, two L-fucose, two D-xylose and three N-acetylglucosamine residues per mole of PG II. The carbohydrate portion of PG II was shown to be attached to the protein part through an N-acetylglucosaminylasparaginyl bond.
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PMID:Carbohydrate composition and electrophoretic properties of tomato polygalacturonase isoenzymes. 661 47

Pectin is a complex structural heteropolysaccharide that require numerous pectinolytic enzymes for its complete degradation. Polygalacturonase from mesophilic or thermophilic origin are being widely used in fruit and vegetable processing in the recent decades to degrade pectic substances. Recently cold active pectinases are finding added advantages over meso and thermophilic counterparts, to use in industrial scale particularly in food processing industry. They facilitate in conservation of several properties of foods so that the end product retains its naturality and also generates economic benefits. In the present study, Pseudoalteromonas haloplanktis, a well reported marine psychrophile is taken as a model organism for cold active polygalacturonase and is evaluated in comparision to the routinely used mesophilic and thermophilic enzymes by insicio approach. Polygalacturonase sequences from industrially important microbial sources were subjected to MEME and Pfam wherein motifs and domains involved in the conservation were analyzed. Dendrogram revealed sequence level similarity and motifs showed uniform distribution of conserved regions that are involved in important functions. It was also observed through clustalW analysis that the amount of arginine content of psychrophiles is less when compared with thermophiles. Finally, all the modeled enzyme structures were subjected to docking studies using Autodock 4.2 with the substrate polygalacturonic acid and binding energies were found to be -5.73, -6.22 and -7.27 KCals/mole for meso, thermo and psychrophiles respectively which indicates the efficiency of psychrophilic enzymes when compared with its counterparts giving scope for further experimentation to find their better usage in various food industry applications.
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PMID:Molecular insights into cold active polygalacturonase enzyme for its potential application in food processing. 2634 63