Linked Life Data

11580273

Source:http://linkedlifedata.com/resource/pubmed/id/11580273

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
40
pubmed:dateCreated
2001-10-2
pubmed:abstractText
The ubiquitous Taxol binding site of microtubules also binds newly discovered ligands. We have designed a homogeneous assay for the high throughput detection of Taxol biomimetics, based on the displacement of 7-O-[N-(2,7-difluoro-4'-fluoresceincarbonyl)-L-alanyl]Taxol from its binding site in diluted solutions of preserved microtubules. The state of this reference ligand is measured by fluorescence anisotropy in a microplate reader, with varying concentrations of nonfluorescent competitors. The binding equilibrium constant of Taxol has a value K(b) = 3.7 x 10(7) M(-1). We have found that baccatin III, an analogue of Taxol without the C-13 side chain, binds with K(b) = 1.5 x 10(5) M(-1), whereas the side chain methyl ester is inactive. This was unexpected from the structure-activity relationship of taxoids but compatible with models of Taxol docked at the microtubule site. Baccatin III binding has been confirmed by displacement of [(3)H]Taxol and by direct HPLC measurements of its cosedimentation with microtubules, among other methods. Consequently, baccatin III induces microtubule bundles and multipolar spindles in PtK2 and U937 cells, and mitotic arrest and apoptotic death of the U937 cells, at concentrations 200-500-fold larger than Taxol. The simplest analysis of these results strongly suggests that the interaction of the C-2 C-4 substituted taxane ring system with the microtubule binding site provides most (ca. 75%) of the free energy change of Taxol binding and is sufficient to activate microtubule stabilization and transmit the antitumor effects of Taxol, whereas the C-13 side chain provides a weak specific anchor.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
9
pubmed:volume
40
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
11975-84
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2001
pubmed:articleTitle
The interaction of baccatin III with the taxol binding site of microtubules determined by a homogeneous assay with fluorescent taxoid.
pubmed:affiliation
Centro de Investigaciones Biológicas, CSIC, Velazquez 144, 28006 Madrid, Spain. j.m.andreu@cib.csic.es
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't