Linked Life Data

1967948

Source:http://linkedlifedata.com/resource/pubmed/id/1967948

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1990-3-26
pubmed:abstractText
We have investigated the inhibition of Escherichia coli glutamine synthetase (GS) with alpha- and gamma-substituted analogues of phosphinothricin [L-2-amino-4-(hydroxymethylphosphinyl)butanoic acid (PPT)], a naturally occurring inhibitor of GS. These compounds display inhibition of bacterial GS that is competitive vs L-glutamate, with Ki values in the low micromolar range. At concentrations greater than Ki the phosphinothricins caused time-dependent loss of enzyme activity, while dilution after enzyme inactivation resulted in recovery of enzyme activity. ATP was required for inactivation; the nonhydrolyzable ATP analogue AMP-PCP failed to support inhibition of GS by the phosphinothricins. The binding of these inhibitors to the enzyme was also characterized by measurement of changes in protein fluorescence, which provided similar inactivation rate constants k1 and k2 for the entire series of compounds. Rate constants koff for recovery were also determined by fluorescence measurement and were comparable for both PPT and the gamma-hydroxylated analogue GHPPT and significantly greater for the alpha- and gamma-alkyl-substituted compounds. Electron paramagnetic resonance spectra provided information on the interaction of the phosphinothricins with the manganese form of the enzyme in the absence of ATP, and significant binding was observed for PPT and GHPPT. 31P NMR experiments confirmed that enzyme inactivation is accompanied by hydrolysis of ATP, although phosphorylated phosphinothricins could not be detected in solution. The kinetic behavior of these compounds is consistent with a mechanism involving inhibitor phosphorylation, followed by release from the active site and simultaneous hydrolysis to form Pi and free inhibitor.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
16
pubmed:volume
29
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
366-72
pubmed:dateRevised
2000-12-18
pubmed:meshHeading
pubmed:year
1990
pubmed:articleTitle
Inhibition of Escherichia coli glutamine synthetase by alpha- and gamma-substituted phosphinothricins.
pubmed:affiliation
Monsanto Agricultural Company, St. Louis, Missouri 63198.
pubmed:publicationType
Journal Article