Linked Life Data

186263

Source:http://linkedlifedata.com/resource/pubmed/id/186263

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1977-1-28
pubmed:abstractText
The nature of the feedback inhibition of the bifunctional enzyme, aspartokinase I-homoserine dehydrogenase I of Escherichia coli was studied using 13C nuclear magnetic resonance (NMR). Since aspartokinase is activated by Mn(II), the interaction of the inhibitor L-threonine (specifically enriched to 90% 13C in the carboxyl carbon) with the metal-enzyme complex was studied. Spin-lattice (T1) and spin-spin (T2) relaxation times were determined by the partially relaxed Fourier transform method and line-width measurements respectively at 20 MHz. The pronounced broadening of the DL-threonine carboxyl peak in the presence of the Mn(II)-enzyme complex indicates that an L-threonine binding site is close to the metal binding site of the kinase active site. The non-identity of (T1)*M and (T2)*M indicates that conditions of fast exchange prevail. The (T1)*M/(T2)*M ratio was used to estimate a correlation time of 2.0 ns for the dipolar interaction at 25 degrees C. An estimate for the distance between Mn(II) and the threonine carboxyl carbon of 4.4 A (0.44 nm) was obtained. This 13C NMR study has thus located one of the two classes of threonine regulatory sites which exist per subunit; the threonine site identified here is at the aspartokinase active site, adjacent to the catalytic metal site.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0014-2956
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
69
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
249-55
pubmed:dateRevised
2007-7-23
pubmed:meshHeading
pubmed:year
1976
pubmed:articleTitle
Nuclear-magnetic-relaxation studies of the interaction of inhibitor with the threonine-sensitive aspartokinase of Escherichia coli.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.