Publication Date:
1988-05-27
Description:
Ion channel proteins are important for the conduction of ions across biological membranes. Recent analyses of their sequences have suggested that they are composed of bundles of alpha-helices that associate to form ion-conducting channels. To gain insight into the mechanisms by which alpha-helices can aggregate and conduct ions, three model peptides containing only leucine and serine residues were synthesized and characterized. A 21-residue peptide, H2N-(Leu-Ser-Ser-Leu-Leu-Ser-Leu)3-CONH2, which was designed to be a membrane-spanning amphiphilic alpha-helix, formed well-defined ion channels with ion permeability and lifetime characteristics resembling the acetylcholine receptor. In contrast, a 14-residue version of this peptide, which was too short to span the phospolipid bilayer as an alpha-helix, failed to form discrete, stable channels. A third peptide, H2N-(Leu-Ser-Leu-Leu-Leu-Ser-Leu)3-CONH2, in which one serine per heptad repeat was replaced by leucine, produced proton-selective channels. Computer graphics and energy minimization were used to create molecular models that were consistent with the observed properties of the channels.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lear, J D -- Wasserman, Z R -- DeGrado, W F -- New York, N.Y. -- Science. 1988 May 27;240(4856):1177-81.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Central Research and Development Department, E. I. du Pont de Nemours and Company, Wilmington, DE 19898.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2453923" target="_blank"〉PubMed〈/a〉
Keywords:
Computer Graphics
;
Electric Conductivity
;
*Ion Channels
;
Leucine
;
*Membrane Proteins
;
Models, Chemical
;
Models, Molecular
;
Peptides/chemical synthesis
;
Protons
;
Serine
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
