rdf:type |
|
lifeskim:mentions |
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pubmed:issue |
4
|
pubmed:dateCreated |
2002-12-13
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pubmed:abstractText |
A beta-primeverosidase from tea (Camellia sinensis) plants is a unique disaccharide-specific glycosidase, which hydrolyzes aroma precursors of beta-primeverosides (6-O-beta-D-xylopyranosyl-beta-D-glucopyranosides) to liberate various aroma compounds, and the enzyme is deeply concerned with the floral aroma formation in oolong tea and black tea during the manufacturing process. The beta-primeverosidase was purified from fresh leaves of a cultivar for green tea (C. sinensis var sinensis cv Yabukita), and its partial amino acid sequences were determined. The beta-primeverosidase cDNA has been isolated from a cDNA library of cv Yabukita using degenerate oligonucleotide primers. The cDNA insert encodes a polypeptide consisting of an N-terminal signal peptide of 28 amino acid residues and a 479-amino acid mature protein. The beta-primeverosidase protein sequence was 50% to 60% identical to beta-glucosidases from various plants and was classified in a family 1 glycosyl hydrolase. The mature form of the beta-primeverosidase expressed in Escherichia coli was able to hydrolyze beta-primeverosides to liberate a primeverose unit and aglycons, but did not act on 2-phenylethyl beta-D-glucopyranoside. These results indicate that the beta-primeverosidase selectively recognizes the beta-primeverosides as substrates and specifically hydrolyzes the beta-glycosidic bond between the disaccharide and the aglycons. The stereochemistry for enzymatic hydrolysis of 2-phenylethyl beta-primeveroside by the beta-primeverosidase was followed by (1)H-nuclear magnetic resonance spectroscopy, revealing that the enzyme hydrolyzes the beta-primeveroside by a retaining mechanism. The roles of the beta-primeverosidase in the defense mechanism in tea plants and the floral aroma formation during tea manufacturing process are also discussed.
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pubmed:commentsCorrections |
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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 |
Dec
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pubmed:issn |
0032-0889
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pubmed:author |
|
pubmed:issnType |
Print
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pubmed:volume |
130
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
2164-76
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pubmed:dateRevised |
2010-9-14
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pubmed:meshHeading |
pubmed-meshheading:12481100-Odors,
pubmed-meshheading:12481100-Tea,
pubmed-meshheading:12481100-Plant Leaves,
pubmed-meshheading:12481100-Escherichia coli,
pubmed-meshheading:12481100-Plant Proteins,
pubmed-meshheading:12481100-Glycoside Hydrolases,
pubmed-meshheading:12481100-Glycosylation,
pubmed-meshheading:12481100-Base Sequence,
pubmed-meshheading:12481100-Amino Acid Sequence,
pubmed-meshheading:12481100-Biological Transport,
pubmed-meshheading:12481100-Molecular Sequence Data,
pubmed-meshheading:12481100-Hydrolysis,
pubmed-meshheading:12481100-Phylogeny
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