Linked Life Data

2404976

Source:http://linkedlifedata.com/resource/pubmed/id/2404976

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1990-3-7
pubmed:abstractText
Enzyme I of the bacterial phosphoenolpyruvate:glycose phosphotransferase system (PTS) exhibits a temperature-dependent monomer/dimer equilibrium. The accompanying paper (Han, M. K., Roseman, S., and Brand, L. (1990) J. Biol. Chem. 265, 1985-1995) shows that the C-terminal -SH residue (Cys-575) can be modified specifically with fluorescent probes such as pyrene maleimide. The derivative retains full enzyme activity, and is capable of forming dimers at room temperature. In the present studies, Enzyme I labeled in this way is found to exhibit a temperature-, concentration-, and pH-dependent monomer/dimer association. The kinetics of dimer formation of Enzyme I is measured in the following way. A derivatized Enzyme I sample is prepared with a pyrene moiety irreversibly attached to the C-terminal -SH residue and 5,5'-dithiobis-2-nitrobenzoic acid reversibly attached to the other 3 -SH residues. This modified enzyme does not form dimers at room temperature. Addition of dithiothreitol results in total release of the thionitrobenzoate anion within 2 min. After the three -SH groups are unblocked, steady-state and nanosecond time-resolved emission anisotropy measurements indicate the dimer is formed over a period of 30 min. In a similar experiment, little dimer formation is observed at 3 degrees C, at temperature at which the native enzyme also does not form dimers. Tryptophan fluorescence is also examined during the release of the thionitrobenzoate. After the completion of thionitrobenzoate release, additional slow steady-state tryptophan fluorescence changes are observed. These results suggest that dimer formation may be preceded by a conformational change following thionitrobenzoate release.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
http://linkedlifedata.com/resource/pubmed/chemical/Dithionitrobenzoic Acid, http://linkedlifedata.com/resource/pubmed/chemical/Macromolecular Substances, http://linkedlifedata.com/resource/pubmed/chemical/Maleimides, http://linkedlifedata.com/resource/pubmed/chemical/N-(3-pyrene)maleimide, http://linkedlifedata.com/resource/pubmed/chemical/Nitrobenzoates, http://linkedlifedata.com/resource/pubmed/chemical/Phosphoenolpyruvate Sugar..., http://linkedlifedata.com/resource/pubmed/chemical/Phosphotransferases (Nitrogenous..., http://linkedlifedata.com/resource/pubmed/chemical/Sulfhydryl Compounds, http://linkedlifedata.com/resource/pubmed/chemical/Sulfhydryl Reagents, http://linkedlifedata.com/resource/pubmed/chemical/phosphoenolpyruvate-protein..., http://linkedlifedata.com/resource/pubmed/chemical/thionitrobenzoic acid
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
5
pubmed:volume
265
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1996-2003
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1990
pubmed:articleTitle
Sugar transport by the bacterial phosphotransferase system. Fluorescence studies of subunit interactions of enzyme I.
pubmed:affiliation
Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.