Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
1993-2-10
pubmed:abstractText
Techniques for determining large transbilayer pH gradients (delta pH) and membrane potentials (delta psi) induced in response to delta pH in large unilamellar vesicle liposomal systems by measuring the transbilayer redistribution of radiolabeled compounds have been examined. For liposomes with acidic interiors, it is shown that protocols using radiolabeled methylamine in conjunction with gel filtration procedures to remove untrapped methylamine provide accurate measures of delta pH in most situations. Exceptions include gel state lipid systems, where transbilayer equilibration processes are slow, and situations where the interior buffering capacity is limited. These problems can be circumvented by incubation at elevated temperatures and by using probes with higher specific activities, respectively. Determination of delta pH in vesicles with a basic interior using weak acid probes such as radiolabeled acetate in conjunction with gel filtration was found to be less reliable, and an alternative equilibrium centrifugation protocol is described. In the case of determinations of the membrane potentials induced in response to these pH gradients, probes such as tetraphenylphosphonium and thiocyanate provide relatively accurate measures of the delta psi induced. It is shown that the maximum transmembrane pH gradient that can be stably maintained by an egg phosphatidylcholine-cholesterol 100-nm-diam large unilamellar vesicle is approximately 3.7 units, corresponding to an induced delta psi of 220 mV or transbilayer electrical field of 5 x 10(5) V/cm.
pubmed:commentsCorrections
http://linkedlifedata.com/resource/pubmed/commentcorrection/1477283-1540691, http://linkedlifedata.com/resource/pubmed/commentcorrection/1477283-1972352, http://linkedlifedata.com/resource/pubmed/commentcorrection/1477283-1993189, http://linkedlifedata.com/resource/pubmed/commentcorrection/1477283-201283, http://linkedlifedata.com/resource/pubmed/commentcorrection/1477283-2114930, http://linkedlifedata.com/resource/pubmed/commentcorrection/1477283-2337579, http://linkedlifedata.com/resource/pubmed/commentcorrection/1477283-2747544, http://linkedlifedata.com/resource/pubmed/commentcorrection/1477283-2775833, http://linkedlifedata.com/resource/pubmed/commentcorrection/1477283-29663, http://linkedlifedata.com/resource/pubmed/commentcorrection/1477283-3006814, http://linkedlifedata.com/resource/pubmed/commentcorrection/1477283-3207727, http://linkedlifedata.com/resource/pubmed/commentcorrection/1477283-3349072, http://linkedlifedata.com/resource/pubmed/commentcorrection/1477283-37402, http://linkedlifedata.com/resource/pubmed/commentcorrection/1477283-3743722, http://linkedlifedata.com/resource/pubmed/commentcorrection/1477283-3839414, http://linkedlifedata.com/resource/pubmed/commentcorrection/1477283-4005257, http://linkedlifedata.com/resource/pubmed/commentcorrection/1477283-6244846, http://linkedlifedata.com/resource/pubmed/commentcorrection/1477283-6492133, http://linkedlifedata.com/resource/pubmed/commentcorrection/1477283-7139025
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0006-3495
pubmed:author
pubmed:issnType
Print
pubmed:volume
63
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1336-45
pubmed:dateRevised
2010-9-7
pubmed:meshHeading
pubmed:year
1992
pubmed:articleTitle
Determination of transmembrane pH gradients and membrane potentials in liposomes.
pubmed:affiliation
Department of Biochemistry, University of British Columbia, Vancouver, Canada.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't