XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
232
T2: P–17
Light-driven reorganization of LHCII supramolecular structure
Ewa Janik
1,2
, Joanna Bednarska
1,3
, Monika Zubik
1,4
, Karol Sowinski
1,5
, Rafal
Luchowski
1
, Wojciech Grudzinski
1
, and Wieslaw I. Gruszecki
1
1
Department of Biophysics, Institute of Physics, Maria Curie-Sklodowska University, Pl. Marii
Curie-Sklodowskiej 1, 20-031 Lublin, Poland, e-mail: ewa.janik@poczta.umcs.lublin.pl
2
Department of Cell Biology, Institute of Biology and Biochemistry, Maria Curie-Sklodowska
University, Akademicka 19, 20–033 Lublin, Poland
3
Department of Medicine, Imperial College London, Du Cane Road, London W12 0NN, UK
4
Institute of Agrophysics of Polish Academy of Sciences, Department of Metrology and Modelling of
Agrophysical Processes, ul. Doswiadczalna 4, 20-290 Lublin, Poland
5
Chair and Department of Synthesis and Chemical Technology of Pharmaceutical Substances,
Faculty of Pharmacy, Medical University, ul. Chodzki 4a, 20-093 Lublin, Poland
The photosynthetic apparatus of higher plants contains several types of pigment-protein
complexes that collaborate to achieve efficient sunlight harvesting. Now it is clear that the light
phase of photosynthesis is powered mainly by the largest pigment-protein complex of
photosystem II - LHCII. It is proven that molecular structure of LHCII which is exceptionally
well suited to perform the antenna function under low or optimal light condition is a trimer.
Each monomer of the trimer is composed of a polypeptide constituting three transmembrane and
two short α-helices. The polypeptide chain binds 8 molecules of chlorophyll a and 6 molecules
of chlorophyll b. Moreover, the complex comprises 4 xanthophyll molecules: 1 violaxanthin (or
zeaxanthin), 1 neoxanthin and 2 luteins [1]. In addition to the antenna function of LHCII, in
high-light condition it is involved in protection against photoinhibition, but less is known about
the photoprotective supramolecular structures of LHCII.
Using native electrophoresis and molecular spectroscopy techniques such as steady-state and
time-resolved fluorescence we showed light-induced changes of LHCII supramolecular
structure. It emerges from numerous experiments that illumination of the LHCII trimers results
in monomerization of the complexes [2,3]. Moreover, under illumination, dimeric forms of
LHCII were observed [3]. Dimers induced by low-light illumination (~100 µmol m-2s-1) are
formed by the dissociation of one monomer from the trimeric structure but dimers induced by
high-light (~1000 µmol m-2s-1) are formed through association of monomers into a distinctively
different molecular form. This LHCII organization is characterized by shortening of the
amplitude-weighted average fluorescence lifetime values in comparison to the fluorescence
lifetime values of the LHCII trimer, monomer and low-light or zeaxanthin induced dimers [3,4].
Thus, high-light induced dimers could be a potential molecular form for effective
photoprotection in plants.
Keywords: LHCII; photoprotection; monomer; dimer; fluorescence spectroscopy
Acknowledgment
This research has been performed within the framework of the project „Molecular Spectroscopy for
BioMedical Studies” financed by the Foundation for Polish Science within the TEAM program
(TEAM/2011-7/2). The research was carried out with the equipment purchased thanks to the financial
support of the European Regional Development Fund in the framework of the Development of Eastern
Poland Operational Programme.
References
[1] Z. Liu, H. Yan, K. Wang, T. Kuang, J. Zhang, L. Gui, X. An, W. Chang, Nature 428 (2004) 287.
[2] E. Janik, J. Bednarska, M. Zubik, K. Sowiński, R. Luchowski, W. Grudziński, W.I. Gruszecki, J. Phys.
Chem. B 116 (2015) 8501.
[3] E. Janik, J. Bednarska, K. Sowiński, R. Luchowski, M. Zubik, W. Grudziński, W.I. Gruszecki,
Photosynth. Res. (2017) DOI: 10.1007/s11120-017-0387-6.
[4] E. Janik, J. Bednarska, M. Zubik, K. Sowiński, R. Luchowski, W. Grudziński, D. Matosiuk, W.I.
Gruszecki, Arch. Biochem. Biopys. 592 (2016) 1.
XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
233
T2: P–18
Singlet oxygen generation using metallocomplexes
of meso-phenothiazinylporphyrins
Alexander Starukhin
1
, Alexander Gorski
2
, Valeri Kniukshto
1
,
Andrei Panarin
1
, Luiza Gaina
3
, and Emese Gal
3
1
B.I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, Independence Av. 68,
220072, Minsk, Belarus, e-mail: a. starukhin@ifanbel.bas-net.by
2
Institute
of
Physical
Chemistry,
Polish
Academy
of
Sciences,
Kasprzaka
44/52,
01-224
Warsaw,
Poland
3
Babes Bolyai University, Faculty of Chemistry and Chemical Engineering, Str. Kogălniceanu 1,
Cluj-Napoca, RO- 400084, Romania
The relationships between structure and photophysical parameters of porphyrins upon modulating
the nature and position of the substituents, the linker conjugation and nature of metal insertion have
been studied by different experimental and theoretical methods more than once. Porphyrins with
different kinds units at meso-positions assume to realize multiplicity of compound structures with
different metals. It was of interest to study the efficiency singlet oxygen generation upon using
metallocomplexes of meso-phenothiazinylporphyrins as As a photosensitizers. Singlet oxygen (
1
O
2
) is
a highly reactive intermediate active in many light-driven catalytic processes and in photodynamic
therapy. Therefore, development and optimization of photoinduced generation of singlet oxygen is of
uppermost importance for these fields of modern chemistry and medicine.
In our report we are presenting spectroscopic and photophysical data obtained for set of
metallocomplexes of meso-phenothiazinylporphyrins (MPP) with different structures and ions of
metals (М – Zn(II), Pd(II) and Cu(II)) as described in [1]. For example, the structures several
compounds from MPP: М-TP2А and М-TP2B are presented on Fig. 1.
a
b
c
Fig. 1. Structures of М-TP2А (a), М-TP2B (b) as well as 1O2 luminescence signal for phenalenone(1),
2 - Pd -TPP; 3 - Pd -TP2В; 4 - Pd -TP2А (4) in CCl4 at 293 K (exc.=417 nm).
The
1
O
2
generation efficiencies were determined in CCl
4
at ambient temperature using
phenalenone (1) as the
1
O
2
quantum yield standard (ϕ(
1
O
2
) = 97 %) and the results of measurements
are presented on Fig.1c. The ϕ(
1
O
2
) values were obtained from analyses of the
1
O
2
phosphorescence
(λ
em
= 1274 nm) intensities observed for air saturated solutions containing 2 – Pd -TPP (ϕ(
1
O
2
) = 88
%); 3 – Pd -TP2В (ϕ(
1
O
2
) = 71 %); 4 – Pd -TP2А (ϕ(
1
O
2
) = 43%) upon using photosensitizers and
phenalenone under the same excitation. The lifetimes of the triplet states for above mentioned
compounds in solvent (CCl
4
) saturated oxygen are: Pd-TPP - 358 ns, 390 ns for Pd-TP2B and 408 ns
for Pd-TP2A, respectively. The data presented indicate a correlation between the efficiency of
generation and the lifetime of compounds in the triplet state. The reasons for this correlation will be
elucidated in the course of further experiments. The quantum yields of singlet oxygen generation for
compounds with ion Cu(II) and similar ligands are demonstrated substantially smaller values: for
CuTP2B – 3%; CuTP2BF – 8% and 5% for CuTP2A.
Keywords: metallocomplexes of meso-phenothiazinylporphyrins; luminescence spectra, singlet oxygen generation;
Acknowledgment
This work was supported Foundation for Fundamental Research of Republic of Belarus (project Ph16RA-007) and
European Union’s Horizon 2020 research and innovation program under grant agreement No 645628.
References
[1] B. Brem, Em. Gal, Luiza Gaina, C. Cristea, A. Gabudean, et al. / Dyes and Pigments 123 (2015) 386.
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