Document Detail


Ion transport through gramicidin A. Water structure and functionality.
MedLine Citation:
PMID:  7692866     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Molecular Dynamics (MD) simulations were performed on a gramicidin A dimer model representing a transmembrane channel. Different from previous simulations the peptide was in contact with bulk water at both ends of the dimer to guarantee a realistic description of the hydration of the biomolecule. The flexible BJH model for water was employed in the simulations and the gramicidin-water, gramicidin-ion and ion-water potentials used are based on molecular orbital calculations. The water structure near the gramicidin was investigated first by a simulation without ions, while for the energy profiles of the ion transport through the channel a potassium or a sodium ion was added. These investigations provide a detailed and conclusive picture on a molecular level of the role of water in the ion transport through a gramicidin A channel and can explain the experimental results on the selectivity between alkali ions, their double or even triple occupancy, the exclusion or permeability of anions depending upon cation concentration and the consequences of differences in the ionic charge. The investigation demonstrate that the water molecules around the gramicidin behave as an integral part of the peptide and the functionality is the result of the whole complex biomolecule-water.
Authors:
M Poxleitner; J Seitz-Beywl; K Heinzinger
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Zeitschrift für Naturforschung. C, Journal of biosciences     Volume:  48     ISSN:  0939-5075     ISO Abbreviation:  Z. Naturforsch., C, J. Biosci.     Publication Date:    1993 Jul-Aug
Date Detail:
Created Date:  1993-12-01     Completed Date:  1993-12-01     Revised Date:  2009-11-04    
Medline Journal Info:
Nlm Unique ID:  8912155     Medline TA:  Z Naturforsch C     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  654-65     Citation Subset:  IM    
Affiliation:
Max-Planck-Institut für Chemie (Otto-Hahn-Institut), Mainz, Bundesrepublik Deutschland.
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MeSH Terms
Descriptor/Qualifier:
Anions
Calorimetry
Cations
Gramicidin / chemistry*
Ion Channels / metabolism*
Macromolecular Substances
Models, Biological
Models, Molecular
Permeability
Potassium
Protein Conformation*
Sodium
Water
Chemical
Reg. No./Substance:
0/Anions; 0/Cations; 0/Ion Channels; 0/Macromolecular Substances; 1405-97-6/Gramicidin; 7440-09-7/Potassium; 7440-23-5/Sodium; 7732-18-5/Water

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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