Methanol modification of the electron paramagnetic resonance signals from the S0 and S2 states of the water-oxidizing complex of Photosystem II

Deák, Zsuzsanna; Peterson, Sindra; Geijer, Paulina; Åhrling, Karin A.

doi:10.1016/s0005-2728(99)00064-x

Cited by 34 publications

(28 citation statements)

References 38 publications

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“…Previous reports showed that methanol concentrations up to 10% (v/v; 2.5 M) do not affect the oxygen-evolution rates (Bernat et al 2002;Deak et al 1999;Force et al 1998), while at 20% (v/v; 5 M) a small, reversible decline was reported (Force et al 1998). The data in Fig.…”

Section: Resultsmentioning

confidence: 53%

“…In such experiments suspensions of PSII samples are illuminated for about 1 min with strong white light in the presence of artificial electron acceptors. These kinds of measurements have been performed by several groups and consistently did not reveal any inhibitory effects of methanol at concentrations of up to 5-10% (v/v) (Bernat et al 2002;Deak et al 1999;Force et al 1998). This finding raises the question as to whether or not methanol really acts as substrate analog in PSII.…”

Section: Introductionmentioning

confidence: 89%

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Effects of methanol on the S i -state transitions in photosynthetic water-splitting

Nöring¹,

Shevela

Ренгер

et al. 2008

Photosynth Res

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From a chemical point of view methanol is one of the closest analogues of water. Consistent with this idea EPR spectroscopy studies have shown that methanol binds at-or at least very close to-the Mn 4 O x Ca cluster of photosystem II (PSII). In contrast, Clark-type oxygen rate measurements demonstrate that the O 2 evolving activity of PSII is surprisingly unaffected by methanol concentrations of up to 10%. Here we study for the first time in detail the effect of methanol on photosynthetic water-splitting by employing a Joliot-type bare platinum electrode. We demonstrate a linear dependence of the miss parameter for S i state advancement on the methanol concentrations in the range of 0-10% (v/v). This finding is consistent with the idea that methanol binds in PSII with similar affinity as water to one or both substrate binding sites at the Mn 4 O x Ca cluster. The possibility is discussed that the two substrate water molecules bind at different stages of the cycle, one during the S 4 ? S 0 and the other during the S 2 ? S 3 transition.

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Section: Resultsmentioning

confidence: 53%

Section: Introductionmentioning

confidence: 89%

Effects of methanol on the S i -state transitions in photosynthetic water-splitting

Nöring¹,

Shevela

Ренгер

et al. 2008

Photosynth Res

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show abstract

“…Small changes in the electronic coupling between the radical and the metal and/or changes in the relaxation properties could lead to a loss of the characteristic form of the signal. This is not unprecedented in this system; indeed, significant solvent-induced changes in the EPR properties of relevant species in PSII have been reported previously (Å hrling et al 1997;Deák et al 1999;Force et al 1998;Messinger et al 1997). Specific experiments are required to test the whether Tyr Z • is responsible for the high-quantum efficiency fraction of terminal electron donors.…”

Section: Quantum Efficiency Distributionsmentioning

confidence: 81%

Quantum efficiency distributions of photo-induced side-pathway donor oxidation at cryogenic temperature in photosystem II

et al. 2008

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We monitored illuminated-minus-dark absorption difference spectra in the range of 450-1100 nm induced by continuous illumination at 8 K of photosystem II (PSII) core complexes from Thermosynechococcus elongatus. The photo-induced oxidation of the side-path donors Cytb(559), beta-carotene and chlorophyll Z, as well as the concomitant stable (t(1/2) > 1 s) reduction of the first plastoquinone electron acceptor, Q(A) (monitored by the well-known 'C550' shift), were quantified as a function of the absorbed photons per PSII. The Q(A) photo-induced reduction data can be described by three distinct quantum efficiency distributions: (i) a very high efficiency of approximately 0.5-1, (ii) a middle efficiency with a very large range of approximately 0.014-0.2, and (iii) a low efficiency of approximately 0.002. Each of the observed side-path donors exhibited similar quantum efficiency distributions, which supports a branched pathway model for side-path oxidation where beta-carotene is the immediate electron donor to the photo-oxidized chlorophyll (P680(+)). The yields of the observed side-path donors account quantitatively for the wide middle efficiency range of photo-induced Q(A) reduction, but not for the PSII fractions that exhibit the highest and lowest efficiencies. The high-efficiency component may be due to Tyr(Z) oxidation. A donor that does not exhibit an identified absorption in the visible-near-IR region is mainly responsible for the lowest efficiency component.

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“…It is well known that methanol can interact with the Mn-cluster and significantly modify its EPR signals in different S states (Messinger et al 1997;Force et al 1998;Deak et al 1999;Su et al 2006;Å hrling et al 2006;Haddy 2007). Methanol can also affect the EPR signals arising from the magnetic interaction between Tyr Z • and the Mn-cluster in various S states .…”

Section: Resultsmentioning

confidence: 99%

Probing tyrosine Z oxidation in photosystem II core complex isolated from spinach by EPR at liquid helium temperatures

et al. 2009

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Tyrosine Z (Tyr(Z)) oxidation observed at liquid helium temperatures provides new insights into the structure and function of Tyr(Z) in active Photosystem II (PSII). However, it has not been reported in PSII core complex from higher plants. Here, we report Tyr(Z) oxidation in the S(1) and S(2) states in PSII core complex from spinach for the first time. Moreover, we identified a 500 G-wide symmetric EPR signal (peak position g = 2.18, trough position g = 1.85) together with the g = 2.03 signal induced by visible light at 10 K in the S(1) state in the PSII core complex. These two signals decay with a similar rate in the dark and both disappear in the presence of 6% methanol. We tentatively assign this new feature to the hyperfine structure of the S(1)Tyr(Z)(*) EPR signal. Furthermore, EPR signals of the S(2) state of the Mn-cluster, the oxidation of the non-heme iron, and the S(1)Tyr(Z)(*) in PSII core complexes and PSII-enriched membranes from spinach are compared, which clearly indicate that both the donor and acceptor sides of the reaction center are undisturbed after the removal of LHCII. These results suggest that the new spinach PSII core complex is suitable for the electron transfer study of PSII at cryogenic temperatures.

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Methanol modification of the electron paramagnetic resonance signals from the S0 and S2 states of the water-oxidizing complex of Photosystem II

Cited by 34 publications

References 38 publications

Effects of methanol on the S i -state transitions in photosynthetic water-splitting

Effects of methanol on the S i -state transitions in photosynthetic water-splitting

Quantum efficiency distributions of photo-induced side-pathway donor oxidation at cryogenic temperature in photosystem II

Probing tyrosine Z oxidation in photosystem II core complex isolated from spinach by EPR at liquid helium temperatures

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