Source:http://linkedlifedata.com/resource/pubmed/id/16661872
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| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
1
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| pubmed:dateCreated |
2010-6-29
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| pubmed:abstractText |
The fact that fungal glucans will stimulate soybeans to accumulate phytoalexins prompted an investigation of soybean cell beta-1,3-glucanases and beta-glucosidases, as well as the ability of these enzymes to hydrolyze the fungal glucans. Several beta-1,3-glucanases and beta-glucosidases can be solubilized from the walls of suspension-cultured soybean cells by treatment with 1.0 molar sodium acetate buffer. An enzyme, which has been termed beta-glucosylase I, is the dominant beta-1,3-glucanase in the cell wall extracts. Utilizing CM-Sephadex chromatography, hydroxylapatite chromatography, and affinity chromatography, beta-glucosylase I has been purified 71-fold, with 39% recovery, from the mixture of cell wall enzymes. The affinity chromatography column material was prepared by covalently attaching p-aminophenyl-1-beta-d-glucopyranoside, an analog of a beta-glucosylase I substrate, to Sepharose. beta-Glucosylase I, purified by this procedure, yields a single band on isoelectric focusing gels (pH 8.9). However, the purified beta-glucosylase I yields a darkly-staining protein band at an apparent molecular weight of 69,000 and several lightly-staining protein bands in sodium dodecyl sulfate polyacrylamide gels. Additional purification procedures fail to remove these lightly-staining protein bands.beta-Glucosylase I will hydrolyze the beta-glucan substrates, laminarin (3-linked) and lichenan (3- and 4-linked), and therefore, possesses beta-glucanase activity. Studies of the progressive hydrolysis of laminarin by beta-glucosylase I demonstrate that the enzyme hydrolyzes polysaccharide substrates in an exo manner. beta-Glucosylase I will also hydrolyze a variety of low molecular weight beta-glucosides including various beta-linked diglucosides. Thus, beta-glucosylase I also possesses beta-glucosidase activity.Several lines of evidence are presented that the beta-glucanase and the beta-glucosidase activities exhibited by purified beta-glucosylase I preparations are catalyzed by the same enzyme. This evidence includes inhibition studies which indicate that the beta-glucanase and the beta-glucosidase activities of beta-glucosylase I are catalyzed at the same active site. beta-Glucosylase I will also catalyze glucosyl transfer. This catalytic activity is responsible for the observed ability of the enzyme to synthesize di- and trisaccharides from laminarin. The disaccharides formed by beta-glucosylase I-catalyzed transglucosylation are the beta-anomers of the 6-, 4-, 3-, and 2-linked diglucosides in the relative proportions of 10:1:1:1. The ability of beta-glucosylase I to catalyze glucosyl transfer indicates that beta-glucosylase I is biochemically more similar to previously studied beta-glucosidases than to beta-glucanases. This conclusion is supported by the observation that beta-glucosylase I is strongly inhibited by 1,5-d-gluconolactone, an inhibitor of beta-glucosidases but not of beta-glucanases.
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| pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/16661872-1033777,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16661872-14402470,
http://linkedlifedata.com/resource/pubmed/commentcorrection/16661872-16657372,
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http://linkedlifedata.com/resource/pubmed/commentcorrection/16661872-5432063,
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http://linkedlifedata.com/resource/pubmed/commentcorrection/16661872-7372570
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| pubmed:language |
eng
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| pubmed:journal | |
| pubmed:status |
PubMed-not-MEDLINE
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| pubmed:month |
Jul
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| pubmed:issn |
0032-0889
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| pubmed:author | |
| pubmed:issnType |
Print
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| pubmed:volume |
68
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| pubmed:owner |
NLM
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| pubmed:authorsComplete |
Y
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| pubmed:pagination |
207-20
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| pubmed:dateRevised |
2010-9-14
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| pubmed:year |
1981
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| pubmed:articleTitle |
Host-Pathogen Interactions: XVI. PURIFICATION AND CHARACTERIZATION OF A beta-GLUCOSYL HYDROLASE/TRANSFERASE PRESENT IN THE WALLS OF SOYBEAN CELLS.
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| pubmed:affiliation |
Department of Chemistry, University of Colorado, Boulder, Colorado 80309.
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| pubmed:publicationType |
Journal Article
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