Linked Life Data

8797836

Source:http://linkedlifedata.com/resource/pubmed/id/8797836

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1996-11-4
pubmed:abstractText
A characteristic property of the tryptophan synthase alpha 2 beta 2 complex is the mutual activation of the alpha and beta subunit upon complex formation. It has been speculated that this mutual activation results from the conformational change due to the alpha/beta subunit interaction. To elucidate this mechanism, we investigated the thermodynamic parameters of association for the various combinations of the alpha and beta subunits from Escherichia coli and Salmonella typhimurium using isothermal titration calorimetry. The negative association enthalpy of the S. typhimurium alpha subunit with the beta subunit from E. coli (or S. typhimurium) was about 20 kJ mol-1 larger than that of the E. coli alpha subunit at 40 degrees C. However, the favorable enthalpy of the S. typhimurium alpha subunit was perfectly compensated by the unfavorable association entropy, therefore, the Gibbs energy of association was similar to that of the E. coli alpha subunit. Furthermore, the site-directed mutagenesis study revealed that a single mutation (K109N; [Asn109] alpha subunit) of the E coli alpha subunit at the subunit interface from E. coli to the S. typhimurium type could change the characteristics of the thermodynamic parameters of association to the S. typhimurium alpha subunit type. The heat-capacity changes of the association of the alpha subunit with the beta subunit were quite great, 6.37-8.21 kJ mol-1 K-1, compared with that due to a decrease in accessible surface area in the subunit interface. The analysis of the thermodynamic parameters of association suggested that the complex formation couples with the folding (rearrangements) of the alpha subunit monomer or/and beta subunit dimer.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0014-2956
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
240
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
63-70
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1996
pubmed:articleTitle
A thermodynamic analysis of conformational change due to the alpha 2 beta 2 complex formation of tryptophan synthase.
pubmed:affiliation
Institute for Protein Research, Osaka University, Japan.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't