Source:http://linkedlifedata.com/resource/pubmed/id/11559154
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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
9
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pubmed:dateCreated |
2001-9-17
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pubmed:abstractText |
A preliminary survey demonstrated activity for alpha-D-glucosidase, alpha-D-mannosidase, alpha-L-arabinosidase, beta-D-glucosidase, beta-D-xylosidase, and beta-D-galactosidase in orange fruit flavedo and albedo tissue. alpha-L-Rhamnosidase was not detected. Subsequently, a beta-glucosidase was purified from mature fruit rag tissue (composed of intersegmental septa, squeezed juice sacs, and fruit core tissue) of Citrus sinensis var. Valencia. The beta-glucosidase exhibited low levels of activity against p-nitrophenyl-beta-D-fucopyranoside (13.5%) and p-nitrophenyl-alpha-D-glucopyranoside (7.0%), compared to its activity against p-nitrophenyl-beta-D-glucopyranoside (pNPG, 100%). The enzyme was purified by a combination of ion exchange (anion and cation) and gel filtration (Superdex and Toyopearl HW-55S) chromatography. It has an apparent molecular mass of 64 kDa by denaturing electrophoresis or 55 kDa by gel filtration chromatography (BioGel P-100). Hydrolysis of pNPG demonstrated a pH optimum between 4.5 and 5.5. At pH 5.0 the temperature optimum was 40 degrees C. At pH 5.0 and 40 degrees C the K(m) for pNPG was 0.1146 mM and it had a V(max) of 5.2792 nkatal x mg(-1) protein (katal = 0.06 International Units = the amount of enzyme that produces, under standard conditions, one micromol of product per min). Of the substrates tested, the enzyme was most active against the disaccharide cellobiose (1-->4), but was not active against p-nitrophenyl-beta-D-cellobioside. High levels of activity also were observed with the disaccharides laminaribiose (1-->3), gentiobiose (1-->6), and sophorose (1-->2). Activity greater than that observed with pNPG was obtained with the flavonoids hesperetin-7-glucoside and prunin (naringenin-7-glucoside), salicin, mandelonitrile-beta-D-glucoside (a cyanogenic substrate), and sinigrin (a glucosinolate). The enzyme was not active against amygdalin, coniferin, or limonin glucoside.
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pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical | |
pubmed:status |
MEDLINE
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pubmed:month |
Sep
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pubmed:issn |
0021-8561
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:volume |
49
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
4457-62
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pubmed:meshHeading |
pubmed-meshheading:11559154-Chromatography, Gel,
pubmed-meshheading:11559154-Citrus,
pubmed-meshheading:11559154-Hydrogen-Ion Concentration,
pubmed-meshheading:11559154-Hydrolysis,
pubmed-meshheading:11559154-Kinetics,
pubmed-meshheading:11559154-Molecular Weight,
pubmed-meshheading:11559154-Temperature,
pubmed-meshheading:11559154-beta-Glucosidase
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pubmed:year |
2001
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pubmed:articleTitle |
Purification and characterization of a beta-glucosidase from Citrus sinensis var. Valencia fruit tissue.
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pubmed:affiliation |
Citrus and Subtropical Products Laboratory, Agricultural Research Service, U.S. Department of Agriculture, 600 Avenue S, NW, Winter Haven, Florida 33881, USA. rcameron@citrus.usda.gov
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pubmed:publicationType |
Journal Article
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