Linked Life Data

11541119

Source:http://linkedlifedata.com/resource/pubmed/id/11541119

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1998-10-31
pubmed:abstractText
The conformational equilibria of the acetyl and methyl amide terminally blocked L-alanine, L-leucine and L-glutamine amino acids are examined in vacuum, in bulk water, and at the water-hexane interface, using multi-nanosecond molecular dynamics simulations. The two-dimensional probability distribution functions of finding the peptides at different dihedral angles of the backbone, phi and psi, are calculated, and free energy differences between different conformational states are determined. All three peptides are interfacially active, i.e. tend to accumulate at the interface even though they are not amphiphilic. Conformational states stable in both gas phase and water are also stable in the interfacial environment. Their populations, however, cannot be simply predicted from the knowledge of conformational equilibria in the bulk phases, indicating that the interface exerts a unique effect on the peptides. Conformational preferences in the interfacial environment arise from the interplay between electrostatic and hydrophobic effects. As in an aqueous solution, electrostatic solute-solvent interactions lead to the stabilization of more polar peptide conformations. The hydrophobic effect is manifested at the interface by a tendency to segregate polar and nonpolar moieties of the solute into the aqueous and the hexane phases, respectively. For the terminally blocked glutamine, this favors conformations for which such a segregation is compatible with the formation of strong, backbone-side chain intramolecular hydrogen bonds on the hexane side of the interface. The influence of the hydrophobic effect can be also noted in the orientational preferences of the peptides at the interface. The terminally blocked leucine is oriented such that its nonpolar side chain is buried in hexane, whereas the polar side chain of glutamine is immersed in water. The free energies of rotating the peptides along the axis parallel to the interface by more than 90 degrees are substantial. This indicates that peptide folding at interfaces is strong by driven by the tendency to adopt amphiphilic structures.
pubmed:keyword
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
S
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
1520-6106
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
102
pubmed:owner
NASA
pubmed:authorsComplete
Y
pubmed:pagination
281-90
pubmed:dateRevised
2007-3-23
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Conformational equilibria of terminally blocked single amino acids at the water-hexane interface. A molecular dynamics study.
pubmed:affiliation
Exobiology Branch, NASA-Ames Research Center, Moffett Field, California 94035-1000, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S.