Linked Life Data

15264836

Source:http://linkedlifedata.com/resource/pubmed/id/15264836

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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
29
pubmed:dateCreated
2004-7-21
pubmed:abstractText
Recent single-molecule atomic force microscopy (AFM) experiments have revealed that some polysaccharides display large deviations from force-extension relationships of other polymers which typically behave as simple entropic springs. However, the mechanism of these deviations has not been fully elucidated. Here we report the use of novel quantum mechanical methodologies, the divide-and-conquer linear scaling approach and the self-consistent charge density functional-based tight binding (SCC-DFTB) method, to unravel the mechanism of the extensibility of the polysaccharide amylose, which in water displays particularly large deviations from the simple entropic elasticity. We studied the deformations of maltose, a building block of amylose, both in a vacuum and in solution. To simulate the deformations in solution, the TIP3P molecular mechanical model is used to model the solvent water, and the SCC-DFTB method is used to model the solute. The interactions between the solute and water are treated by the combined quantum mechanical and molecular mechanical approach. We find that water significantly affects the mechanical properties of maltose. Furthermore, we performed two nanosecond-scale steered molecular dynamics simulations for single amylose chains composed of 10 glucopyranose rings in solution. Our SCC-DFTB/MM simulations reproduce the experimentally measured force-extension curve, and we find that the force-induced chair-to-boat transitions of glucopyranose rings are responsible for the characteristic plateau in the force-extension curve of amylose. In addition, we performed single-molecule AFM measurements on carboxymethyl amylose, and we found that, in contrast to the results of an earlier work by others, these side groups do not significantly affect amylose elasticity. By combining our experimental and modeling results, we conclude that the nonentropic elastic behavior of amylose is governed by the mechanics of pyranose rings themselves and their force-induced conformational transitions.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0002-7863
pubmed:author
pubmed:issnType
Print
pubmed:day
28
pubmed:volume
126
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
9033-41
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2004
pubmed:articleTitle
Elastic properties of single amylose chains in water: a quantum mechanical and AFM study.
pubmed:affiliation
Department of Chemistry, Duke University, Durham, North Carolina 27708, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.