Linked Life Data

9523705

Source:http://linkedlifedata.com/resource/pubmed/id/9523705

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1998-4-23
pubmed:abstractText
The affinity of potato tuber starch-branching enzyme-I (PSBE-I) for various linear malto-oligosaccharides, cyclodextrins, (CDs) and macromolecular alpha-glucans was investigated by alpha-glucan induced fluorescence quenching of intrinsic PSBE-I tryptophan residues and by affinity electrophoresis. alpha-Glucan binding was characterised by distinct shifts towards shorter wavelengths of the PSBE-I fluorescence emission spectrum and by concomitant reductions in fluorescence intensity. The magnitudes of both the maximum shift in emission spectrum and reduction in fluorescence intensity were dependent on the alpha-glucan ligands used. Maximum Kd for a range of linear malto-oligosaccharides analysed was 0.13 mM as found at a degree of polymerisation (DP) of 13. Large differences in dissociation constants were measured for CDs with DP 6 (alpha-CD, 6.0 mM), DP 7 (beta-CD, 0.25 mM) and DP 8 (gamma-CD, 0.67 microM). The high-molecular-mass alpha-glucans amylose and amylopectin, both substrates for PSBE-I, showed apparent affinities of 0.018 and 0.066 mg/ml, respectively. Small linear and cyclic oligosaccharides competed with amylopectin in the affinity electrophoresis system and they were also competitive inhibitors for PSBE-I activity. The affinities for oligosaccharides as measured by competition were, however, about 10-fold lower than as measured by fluorescence quenching suggesting the existence of a separate oligosaccharide binding site on PSBE-I. Affinity electrophoresis revealed multiform heterogeneity in the enzyme preparation with respect to alpha-glucan interaction.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0014-2956
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
252
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
331-8
pubmed:dateRevised
2007-7-23
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Alpha-glucan binding of potato-tuber starch-branching enzyme I as determined by tryptophan fluorescence quenching, affinity electrophoresis and steady-state kinetics.
pubmed:affiliation
Cooperative Research Centre for Plant Science, Canberra, Australia.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't