Linked Life Data

11460542

Source:http://linkedlifedata.com/resource/pubmed/id/11460542

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2001-7-19
pubmed:abstractText
Photoacoustic measurements using a broad frequency band hydrophone were carried out in photosynthetic reaction centers (RC) isolated from Rhodobacter sphaeroides R-26 purple bacteria. Data were extracted on enthalpy and volume changes accompanying the primary steps after excitation in the range of 0-500 microseconds aimed at further characterizing the thermodynamic properties of the RC. Quinone titration showed that the volume contraction accompanying the electron transport is sensitive to the molecular species occupying the secondary quinone site. delta VM = 14.4, 7.7 and 4.3 cm3 molar volume contractions were calculated from the measured parameters for 1, 2 and 0.07 quinone/RC after light excitation. Comparing the enthalpy changes (delta H) to the Gibbs free energy data in the literature, a rather large (26%) entropic contribution to the free energy changes (delta G) is estimated for the P*QAQB-->P+QA-QB electron transport (where QA and QB represent primary and secondary quinones, respectively). This is in contrast to previous estimations that delta G = delta H in these processes. On the other hand, only a small (4%) entropic contribution to the delta G of the P*QAQB-->P+QAQB- process is estimated, in agreement with the literature data. Our results are in good agreement with the data obtained earlier (Edens et al. [2000] J. Am. Chem. Soc. 122, 1479-1485).
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0031-8655
pubmed:author
pubmed:issnType
Print
pubmed:volume
74
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
81-7
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2001
pubmed:articleTitle
Thermal and structural changes of photosynthetic reaction centers characterized by photoacoustic detection with a broad frequency band hydrophone.
pubmed:affiliation
Department of Biophysics, Szeged University, Szeged Egyetem u. 2. H-6722, Hungary. lnagy@sol.cc.u-szeged.hu
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't