Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
8
pubmed:dateCreated
2006-3-27
pubmed:abstractText
Disaccharides such as sucrose and trehalose play an important role in stabilizing cellular structures during dehydration. In fact, most organisms that are able to survive desiccation accumulate high concentrations of sugars in their cells. The mechanisms involved in the stabilization of cellular membranes in the dry state have been investigated using model membranes, such as phosphatidylcholine liposomes. It has been proposed that the lyoprotection of liposomes depends on the depression of the gel to liquid-crystalline phase transition temperature (T(m)) of the dry membranes below ambient and on the prevention of membrane fusion by sugar glass formation, because both lead to leakage of soluble content from the liposomes. Since fusion is prevented at lower sugar/lipid mass ratios than leakage, it has been assumed that more sugar is needed to depress T(m) than to prevent fusion. Here, we show that this is not the case. In air-dried egg phosphatidylcholine liposomes, T(m) is depressed by >60 degrees C at sucrose/lipid mass ratios 10-fold lower than those needed to depress fusion to below 20%. In fact, T(m) is significantly reduced at mass ratios where no bulk sugar glass phase is detectable by Fourier transform infrared spectroscopy or differential scanning calorimetry. A detailed analysis of the interactions of sucrose with the P=O, C=O, and choline groups of the lipid and a comparison to published data on water binding to phospholipids suggests that T(m) is reduced by sucrose through a "water replacement" mechanism. However, the sucrose/lipid mass ratios necessary to prevent leakage exceed those necessary to prevent both phase transitions and membrane fusion. We hypothesize that kinetic phenomena during dehydration and rehydration may be responsible for this discrepancy.
pubmed:commentsCorrections
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pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0006-3495
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
90
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2831-42
pubmed:dateRevised
2010-9-20
pubmed:meshHeading
pubmed:year
2006
pubmed:articleTitle
Low amounts of sucrose are sufficient to depress the phase transition temperature of dry phosphatidylcholine, but not for lyoprotection of liposomes.
pubmed:affiliation
Max-Planck-Institut für Molekulare Pflanzenphysiologie, D-14424 Potsdam, Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't