Linked Life Data

2484929

Source:http://linkedlifedata.com/resource/pubmed/id/2484929

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1991-4-26
pubmed:abstractText
X-ray crystal structure determinations and energy-minimization techniques provide conformational data on the complexed and uncomplexed forms of ion transport antibiotics of the shuttle and channel types. In the solid state, hexadecaisoleucinomycin (HEXIL), an analogue of valinomycin, is observed as an asymmetric macrocycle stabilized by eight intramolecular (4----1) hydrogen bonds. The structure obtained from energy-minimization procedures exhibits a greater variation in phi and psi angles of chemically equivalent residues than does the crystallographically observed structure. The structure has eight carbonyl groups directed toward its interior and is capable of providing flexible coordination to a positively charged ion or molecule. These structural findings are consistent with the observed capacity of HEXIL to complex cesium ions, tetramethyl ammonium ions and acetylcholine. Gramicidin A is a pentadecapeptide that functions as a transmembrane channel for transporting monovalent cations. Uncomplexed gramicidin A crystallizes as a left-handed, antiparallel, double-stranded, helical dimer with 5.6 amino acid residues per turn. The helix has an overall length of 31 A and an average inner channel diameter of 4.8 A. The channel of this crystalline form does not contain ions or solvent molecules. Transporting ions through this channel could be achieved only by some expansion of the channel opening that would involve breaking and reforming hydrogen bonds that stabilize the double-stranded helix.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0263-7855
pubmed:author
pubmed:issnType
Print
pubmed:volume
7
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
82-6, 99
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1989
pubmed:articleTitle
Molecular conformation and ion transport of cyclic and linear ionophores.
pubmed:affiliation
Medical Foundation of Buffalo, Inc., NY 14203.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.