Linked Life Data

9917380

Source:http://linkedlifedata.com/resource/pubmed/id/9917380

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1999-3-1
pubmed:abstractText
Membranes have a potent ability to promote secondary structure formation in a wide range of membrane-active peptides, believed to be due to a reduction through hydrogen bonding of the energetic cost of partitioning peptide bonds. This process is of fundamental importance for understanding the mechanism of action of toxins and antimicrobial peptides and the stability of membrane proteins. A classic example of membrane-induced folding is the bee-venom peptide melittin that is largely unstructured when free in solution, but strongly adopts an amphipathic alpha-helical conformation when partitioned into membranes. We have determined the energetics of melittin helix formation through measurements of the partitioning free energies and the helicities of native melittin and of a diastereomeric analog with four d-amino acids (d4,l-melittin). Because D4,l-melittin has little secondary structure in either the free or bound forms, it serves as a model for the experimentally inaccessible unfolded bound form of native melittin. The partitioning of native melittin into large unilamellar phosphocholine vesicles is 5.0(+/-0.7) kcal mol-1 more favorable than the partitioning of d4,l-melittin (1 cal=4.186 J). Differences in the circular dichroism spectra of the two forms of melittin indicate that bound native melittin is more helical than bound d4, l-melittin by about 12 residues. These findings disclose that the free energy reduction per residue accompanying the folding of melittin in membrane interfaces is about 0.4 kcal mol-1, consistent with the hypothesis that hydrogen bonding reduces the high cost of partitioning peptide bonds. A value of 0.6 kcal mol-1 per residue has been observed for beta-sheet formation by a hexapeptide model system. These two values provide a useful rule of thumb for estimating the energetic consequences of membrane-induced secondary structure formation.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0022-2836
pubmed:author
pubmed:copyrightInfo
Copyright 1999 Academic Press.
pubmed:issnType
Print
pubmed:day
29
pubmed:volume
285
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1363-9
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Folding of amphipathic alpha-helices on membranes: energetics of helix formation by melittin.
pubmed:affiliation
Department of Physiology and Biophysics, University of California at Irvine, Irvine, CA, 92697-4560, USA.
pubmed:publicationType
Journal Article, In Vitro, Research Support, U.S. Gov't, P.H.S.