Linked Life Data

10818788

Source:http://linkedlifedata.com/resource/pubmed/id/10818788

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
2000-6-5
pubmed:abstractText
Low-temperature absorption, fluorescence and persistent non-photochemical hole-burned spectra are reported for the CP29 chlorophyll (Chl) a/b antenna complex of photosystem II of green plants. The absorption-origin band of the lowest Qy-state lies at 678.2 nm and carries a width of approximately 130 cm-1 that is dominated by inhomogeneous broadening at low temperatures. Its absorption intensity is equivalent to that of one of the six Chl a molecules of CP29. The absence of a significant satellite hole structure produced by hole burning, within the absorption band of the lowest state, indicates that the associated Chl a molecule is weakly coupled to the other Chl and, therefore, that the lowest-energy state is highly localized on a single Chl a molecule. The electron-phonon coupling of the 678.2 nm state is weak with a Huang-Rhys factor S of 0.5 and a peak phonon frequency (omega m) of approximately 20 cm-1. These values give a Stokes shift (2S omega m) in good agreement with the measured positions of the absorption band at 678.2 nm and a fluorescence-origin band at 679.1 nm. Zero-phonon holes associated with the lowest state have a width of approximately 0.05 cm-1 at 4.2 K, corresponding to a total effective dephasing time of approximately 400 ps. The temperature dependence of the zero-phonon holewidth indicates that this time constant is dominated at temperatures below 8 K by pure dephasing/spectral diffusion due to coupling of the optical transition to the glass-like two-level systems of the protein. Zero-phonon hole-widths obtained for the Chl b bands at 638.5 and 650.0 nm, at 4.2 K, lead to lower limits of 900 +/- 150 fs and 4.2 +/- 0.3 ps, respectively, for the Chl b-->Chl a energy-transfer times. Downward energy transfer from the Chl a state(s) at 665.0 nm occurs in 5.3 +/- 0.6 ps at 4.2 K.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0031-8655
pubmed:author
pubmed:issnType
Print
pubmed:volume
71
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
574-81
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2000
pubmed:articleTitle
Assignment of the lowest Qy-state and spectral dynamics of the CP29 chlorophyll a/b antenna complex of green plants: a hole-burning study.
pubmed:affiliation
Institute of Physics, Humboldt University, Berlin, Germany.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't