Linked Life Data

10471802

Source:http://linkedlifedata.com/resource/pubmed/id/10471802

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1999-10-12
pubmed:abstractText
The H(+)-ATPases from Escherichia coli, EF(0)F(1), and from chloroplasts, CF(0)F(1), were reconstituted in liposomes from phosphatidylcholine/phosphatidic acid. The proteoliposomes were energized by an acid-base transition and a K(+)/valinomycin diffusion potential and the initial rate of ATP synthesis was measured as a function of the transmembrane pH difference, DeltapH, and the electric potential difference, Deltaφ. With EF(0)F(1), a rate of 80 s(-1) is observed at DeltapH=4.1 and Deltaφ approximately 140 mV. The rate decreases sigmoidally with Deltaφ and at Deltaφ approximately 0 mV, the rate is about 1 s(-1) although DeltapH is still 4.1. Under the same conditions with CF(0)F(1), a rate of 280 s(-1) is observed which decreases to 190 s(-1) when Deltaφ is abolished, i.e. ATP synthesis catalyzed by EF(0)F(1) and CF(0)F(1) depends in a different way on DeltapH and Deltaφ. EF(0)F(1)-catalyzed ATP synthesis was measured as a function of DeltapH at a constant Deltaφ. The rate depends sigmoidally on DeltapH reaching a maximal rate which cannot be further increased by increasing DeltapH. However, this maximal rate depends on Deltaφ, i.e. DeltapH and Deltaφ are not kinetically equivalent in driving ATP synthesis. We assume that EF(0)F(1) must be converted into a metastable, active state before it catalyzes proton transport-coupled ATP synthesis. For EF(0)F(1), this activation step depends only on Deltaφ, whereas for CF(0)F(1), the activation depends on DeltapH and Deltaφ.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0014-5793
pubmed:author
pubmed:issnType
Print
pubmed:day
3
pubmed:volume
457
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
327-32
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Comparison of DeltapH- and Delta***φ***-driven ATP synthesis catalyzed by the H(+)-ATPases from Escherichia coli or chloroplasts reconstituted into liposomes.
pubmed:affiliation
Institut für Physikalische Chemie, Universität Freiburg, Albertstr. 23a, D-79104, Freiburg, Germany. fischsus@ruf.uni-freiburg.de
pubmed:publicationType
Journal Article, Comparative Study