Linked Life Data

11594067

Source:http://linkedlifedata.com/resource/pubmed/id/11594067

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2001-10-11
pubmed:abstractText
The enthalpy (delta H) and structural volume changes (delta V) associated with the formation and decay of the early intermediate K600 in the photocycle of Natronobacterium pharaonis halorhodopsin (pHR), an inward-directed anion pump, were obtained by laser-induced optoacoustic spectroscopy. A large expansion is associated with K600 formation, its value depending on the medium and on the anion (Cl-, NO3-, Br-, I-). A smaller expansion is associated with K600 decay to L520. A contraction is found for the same step in the case of the azide-loaded pHR which is an efficient outward-directed proton pump. Thus, the conformational changes in L520 determine the direction and sign of charge translocation. The linear correlation between delta H and delta V for chloride-loaded pHR observed upon mild medium variations is attributed to enthalpy-entropy compensation effects and allows the calculation of the free-energy changes, delta GK = (97 +/- 16) kJ/mol and delta GKL = -(2 +/- 2) kJ/mol. Different from other systems, delta S correlates negatively with delta V in the first steps of the pHR photocycle. Thus, the space around the anion becomes larger and more rigid during each of these two steps. The photocycle quantum yield was 0.52 for chloride-pHR as measured by laser flash photolysis.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0031-8655
pubmed:author
pubmed:issnType
Print
pubmed:volume
74
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
495-503
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2001
pubmed:articleTitle
Thermodynamics of the early steps in the photocycle of Natronobacterium pharaonis halorhodopsin. Influence of medium and of anion substitution.
pubmed:affiliation
Max-Planck-Institut für Strahlenchemie, Postfach 101365, D-45413 Mülheim an der Ruhr, Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't