Renger G.
Max-Volmer-Institut for Biophysical Chemistry und Biochemistry, Technical University Berlin, StraЯe des 17. Juni 135, 10623 Berlin, Germany
Photosynthetic water cleavage is the key process of biological solar
energy exploitation [1]. The overall reaction takes place in a multimeric
integral membrane protein complex referred to as Photosystem II (PS II)
and comprises three types of reaction sequences:
- generation of electronically excited singlet states, migration to the
photochemically active chlorophyll a component P680 and trapping in the
form of a stabilised radical pair
[2],
- oxidation of two water molecules to dioxygen and four protons via a
sequence of four single electron abstraction steps energetically driven
by P680+· as oxidant [3] and
- reduction of one plastoquinone molecule to plastoquinol via a sequence
of two single electron transfer steps with
as reductant [4].
The present report provides a concise summary on our current state of
knowledge of the functional and structural organization of these reactions.
Recent data will be presented which was gathered from experiments using
time resolved single photon counting of fluorescence decay, nonlinear fluorescence
and absorption, flash induced changes of absorption and fluorescence yield.
It is also shown that structural information can be obtained for distances
between functional groups in PS II by evaluation of spectroscopic and kinetic
data.
- G.Renger (1983) Biological Energy Conservation. In: Biophysics (W.
Hoppe, W. Lohmann, H. Markl and H. Ziegler, eds.) pp. 347- 371, Springer,
Berlin
- G. Renger (1992) Energy transfer and trapping in Photosystem II In:
Topics in Photosynthesis, The Photosystems: Structure, Function and Molecular
Biology (Barber, J., ed.), pp. 45 - 99, Elsevier, Amsterdam
- G. Renger (1997) Mechanistic and structural aspects of photosynthetic
water oxidation. Physiol. Plant. 100, 828-841
- Lavergne, J., Briantais, J.M. (1996) In: Ort, D.R., Yocum, C.F. (eds)
Oxygenic Photosynthesis: The Light Reactions, Kluwer Academic Publishers,
pp 265-287