Linked Life Data

17335500

Source:http://linkedlifedata.com/resource/pubmed/id/17335500

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2007-3-5
pubmed:databankReference
pubmed:abstractText
* Invertases and fructan exohydrolases (FEHs) fulfil important physiological functions in plants. Sucrose is the typical substrate for invertases and bacterial levansucrases but not for plant FEHs, which are usually inhibited by sucrose. * Here we report on complexes between chicory (Cichorium intybus) 1-FEH IIa with the substrate 1-kestose and the inhibitors sucrose, fructose and 2,5 dideoxy-2,5-imino-D-mannitol. Comparisons with other family GH32 and 68 enzyme-substrate complexes revealed that sucrose can bind as a substrate (invertase/levansucrase) or as an inhibitor (1-FEH IIa). * Sucrose acts as inhibitor because the O2 of the glucose moiety forms an H-linkage with the acid-base catalyst E201, inhibiting catalysis. By contrast, the homologous O3 of the internal fructose in the substrate 1-kestose forms an intramolecular H-linkage and does not interfere with the catalytic process. Mutagenesis showed that W82 and S101 are important for binding sucrose as inhibitor. * The physiological implications of the essential differences in the active sites of FEHs and invertases/levansucrases are discussed. Sucrose-inhibited FEHs show a K(i) (inhibition constant) well below physiological sucrose concentrations and could be rapidly activated under carbon deprivation.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0028-646X
pubmed:author
pubmed:issnType
Print
pubmed:volume
174
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
90-100
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
Insights into the fine architecture of the active site of chicory fructan 1-exohydrolase: 1-kestose as substrate vs sucrose as inhibitor.
pubmed:affiliation
Laboratorium voor Biokristallografie, Faculteit Farmaceutische Wetenschappen, KU Leuven, Herestraat 49, O & N II, bus 822, B-3000 Leuven, Belgium.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't