Linked Life Data

2554965

Source:http://linkedlifedata.com/resource/pubmed/id/2554965

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
18
pubmed:dateCreated
1990-1-11
pubmed:abstractText
The purified ATPase (F1F0) of Propionigenium modestum has its pH optimum at pH 7.0 or at pH 6.0 in the presence or absence of 5 mM NaCl, respectively. The activation by 5 mM NaCl was 12-fold at pH 7.0, 3.5-fold at pH 6.0, and 1.5-fold at pH 5.0. In addition to its function as a primary Na+ pump, the ATPase was capable of pumping protons. This activity was demonstrated with reconstituted proteoliposomes by the ATP-dependent quenching of the fluorescence of 9-amino-6-chloro-2-methoxyacridine. No delta pH was formed in the presence of the uncoupler carbonyl cyanide m-chlorophenylhydrazone or by blocking the ATPase with dicyclohexylcarbodiimide. In the presence of valinomycin and K+, the delta pH increased, in accord with the operation of an electrogenic proton pump. The proton pump was only operative at low Na+ concentrations (less than 1 mM), and its activity increased as the Na+ concentration decreased. Parallel to the decrease of H+ pumping, the velocity of the Na+ transport increased about 6-fold from 0.1 to 4 mM NaCl, indicating a switch from H+ to Na+ pumping, as the Na+ concentration increases. Due to proton leaks in the proteoliposomal membranes, fluorescence quenching was released after blocking the ATPase with dicyclohexylcarbodiimide, by trapping residual ATP with glucose and hexokinase, or by the Na+-induced conversion of the proton pump onto a Na+ pump. Amiloride, an inhibitor of various Na+-coupled transport systems, was without effect on the kinetics of Na+ transport by the P. modestum ATPase.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
5
pubmed:volume
28
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
7194-8
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1989
pubmed:articleTitle
The sodium ion translocating adenosinetriphosphatase of Propionigenium modestum pumps protons at low sodium ion concentrations.
pubmed:affiliation
Institut für Physiologische Chemie der Technischen Universität München, Federal Republic of Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't