Linked Life Data

2482762

Source:http://linkedlifedata.com/resource/pubmed/id/2482762

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
1990-3-23
pubmed:abstractText
The effect of water present at the mouth and inside the channel of Gramicidin A on the energy profile calculated for a caesium ion is determined. The total optimal interaction energy computed for the system GA-Cs+-(22 waters) leads to an energy profile characterized by a deep minimum at 11 A followed by an entrance energy barrier of 7 Kcal/mol expanding until 9 A from the center. After this point, a second minimum less deep than the previous one is observed, itself followed by a central barrier. The shape of the profile at the entrance is governed by the balance between the progressive desolvation process of the ion and the increase of favorable hydrogen bond interactions implying both the water molecules and GA. The comparison of this energy profile with that obtained in vacuo shows that the presence of water molecules does not modify the pathway of the ion which, owing to its size, is constrained essentially to remain on the channel axis. The comparison Na+ versus Cs+ indicates that although the phenomena involved are globally the same, differences between the two profiles appear due firstly to the difference in the affinity of the two ions for water and secondly to their respective size. This last difference implies that the number of water molecules present in the interior of the channel during the cation progression is reduced roughly by one in the case of caesium. The desolvation barrier computed for Cs+ is half the corresponding value for Na+, a result in agreement with the observed selectivity.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0739-1102
pubmed:author
pubmed:issnType
Print
pubmed:volume
5
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1111-25
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1988
pubmed:articleTitle
Energy profile of Cs+ in gramicidin A in the presence of water. Problem of the ion selectivity of the channel.
pubmed:affiliation
Laboratoire de Biochimie Théorique associé au CNRS, Institut de Biologie Physico-Chimique, Paris, France.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't