Linked Life Data

6400917

Source:http://linkedlifedata.com/resource/pubmed/id/6400917

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1990-3-20
pubmed:abstractText
The alkali-ion binding properties of two natural depsipeptide ion carriers, enniatin B (EnB) and valinomycin (VM), are examined and compared by the empirical force field method. While VM has been shown to bind preferentially K+, Rb+, and Cs+ over Na+ in most solvents, EnB is considerably less specific. We find that EnB forms two kinds of complexes, internal and external. In internal complexes, the ion binds to all six carbonyl oxygens, while in external ones, only three oxygens, preferentially those of the D-hydroxy-isovaleryl residues, are bound. The size of the internal cavity is best suited for Na+, while K+ and Rb+ squeeze in asymmetrically by distorting the molecule, and Cs+ not at all. External binding is much less specific. Since internal complexes possess much higher strain energies than external ones, the latter may be at least as stable as the former, even in fairly non-polar solvents. VM is calculated to bind only internally, and with much less strain energy than EnB. The size of its internal cavity is well suited for binding the ions K+, Rb+, and Cs+, but is too big for Na+. The difference between the binding energies of Na+ and K+ is much smaller than that between the corresponding hydration enthalpies, thus explaining the binding preference for the latter ion.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0739-1102
pubmed:author
pubmed:issnType
Print
pubmed:volume
2
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
641-61
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1984
pubmed:articleTitle
Enniatin B and valinomycin as ion carriers: an empirical force field analysis.
pubmed:affiliation
Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't