The nature of molecular oxygen binding and activation in Mn-O2 complex

Plant chloroplasts emit signals that regulate the expression of nuclear-encoded genes, a process known as retrograde signaling. Environmental stresses, such as rapid and dynamic changes in light intensity and quality, temperature, relative humidity, water and CO 2 availability, cause excess absorption of light energy (EEE) and induce chlorophyll fluorescence and heat dissipation, which lead to the generation of singlet stages of dioxygen, chlorophyll and carotenoid molecules. These primary quantum events in photosynthesis induce secondary redox reactions in photosystems, e.g. electrical charge separation, chloroplast lumen acidification and activation of the xanthophyll cycle by means of non-photochemical quenching (NPQ), redox reactions between the photosynthetic electron carriers (electron transport), and formation of reactive oxygen species. These, in turn, induce cascades of physiologically regulated redox reactions in the chloroplast stroma metabolism that regulate cellular light memory. Recently published data suggest that plants, with the help of EEE, NPQ, photoelectrochemical-redox retrograde signaling and cellular light memory, are able to perform biological processing in order to optimize their photosynthesis, transpiration, light acclimatory and defense responses, and in consequence, their Darwinian fitness. Understanding of the above-mentioned processes is crucial for future biotechnological amelioration of crop production.

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“…Fe 3+ , !C OH could be formed and induce a chain reaction of, e.g. lipid peroxidation (Fridovich, 1997;Kobzev and Urvaev, 2006).…”

Section: Pauli Exclusion Principle and Quantum-redox Reactions In Plmentioning

confidence: 99%

Cellular light memory, photo-electrochemical and redox retrograde signaling in plants

Karpiński

Szechyńska‐Hebda²

2012

bta

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“…Singlet molecular oxygen ( 1 O 2 ) can be generated from triplet molecular oxygen ( 3 O 2 ) via photochemical processes in vivo. − 1 O 2 is highly reactive and harmful in biological systems. 1 O 2 is also thought to be generated from superoxide (O 2 •– ) and hydrogen peroxide (H 2 O 2 ) in the absence of light. − Figure shows the electron configurations of the ground state ( 3 ∑ g – ), degenerate first excited states ( 1 Δ g and 1 Δ g ′), and second excited state ( 1 ∑ g + ) of molecular oxygen, where the excitation energy from 3 O 2 ( 3 ∑ g – ) to 1 O 2 ( 1 Δ g ) is ∼1 eV . While 3 O 2 – 1 O 2 conversion via intersystem crossing is generally slow, 1 O 2 can be efficiently generated via spin-allowed reactions with photosensitizer species. − For example, 1 O 2 can be generated as a byproduct of photosynthesis through energy transfer from the triplet state of pigments (e.g., chlorophyll), which may be generated occasionally via intersystem crossing. − …”

Section: Introductionmentioning

confidence: 99%

“…•− ) and hydrogen peroxide (H 2 O 2 ) in the absence of light. 2−4 Figure 1 shows the electron configurations of the ground state ( 3 ∑ g − ), degenerate first excited states ( 1 Δ g and 1 Δ g ′), and second excited state ( 1 ∑ g + ) of molecular oxygen, 11 where the excitation energy from 3 O 2 ( 3 ∑ g − ) to 1 O 2 ( 1 Δ g ) is ∼1 eV. 1 While 3 O 2 − 1 O 2 conversion via intersystem crossing is generally slow, 1 O 2 can be efficiently generated via spinallowed reactions with photosensitizer species.…”

Section: ■ Introductionmentioning

confidence: 99%

Quenching of Singlet Oxygen by Carotenoids via Ultrafast Superexchange Dynamics

Tamura

Ishikita

2020

J. Phys. Chem. A

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We analyze the quenching mechanism of singlet molecular oxygen ( 1 O 2 ) by carotenoids, namely lycopene, β-carotene, astaxanthin, and lutein, by means of quantum dynamics calculations and ab initio calculations. The singlet carotenoid ( 1 Car) and 1 O 2 molecules can form a weakly bound complex via donation of electron density from the highest occupied molecular orbital (HOMO) of the carotenoid to the π g * orbitals of 1 O 2 . The Dexter-type superexchange via charge transfer states (Car •+ /O 2 •− ) governs the 1 O 2 quenching. The Car •+ /O 2 •− states are substantially higher in energy (2−4 eV) than the initial 1 Car/ 1 O 2 states. The quantum dynamics calculations indicate an ultrafast 1 O 2 quenching on a timescale of subpicosecond owing to the strong electronic couplings in the carotenoid/O 2 complexes. The superexchange mechanism via the Car •+ /O 2 •− states dominates the 1 O 2 quenching, although the direct two-electron coupling can also play a certain role. Article pubs.acs.org/JPCA

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“…Selenium dioxide SeO 2 and metastable excited Se-O 2 intermediates [6,7] as well as superoxo-and peroxocomplexes of transition metals [8,9] have excessive energy and enhanced reactivity. It is unknown whether the decay of these systems can be accompanied by the formation of reactive oxygen species (ROS) or not, e.g.…”

Section: Introductionmentioning

confidence: 99%

A quantum chemical study of photochemical processes in the reaction Se + O2 → SeO2 with allowance for the spin orbit interaction

et al. 2012

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DFT, SA-MCSCF, and MRMP/MCQDPT2 methods in the 6-311++G(2d) basis set are employed to consider the features of the formation reaction of key intermediates (SeOO, Se(O 2 )) and photochemical dissociation of selenium dioxide with the formation of singlet oxygen. The cross-sections of potential energy surfaces of SeO 2 , Se(O 2 ), and SeOO are constructed and the terms of their ground and excited states are analyzed at the SeOO dissociation limit with regard to spin-orbital interaction. Possible formation channels of 1 О 2 ( 1 Δ g , 1 ) g + ∑ reactive oxygen species during the decay of the excited states of selenium oxocomplexes are revealed. The effect of the spin-orbit interaction on the character of electronic spectrum transitions and zero field splitting in oxygen is estimated.

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The nature of molecular oxygen binding and activation in Mn-O2 complex

Cited by 4 publications

References 10 publications

Cellular light memory, photo-electrochemical and redox retrograde signaling in plants

Cellular light memory, photo-electrochemical and redox retrograde signaling in plants

Quenching of Singlet Oxygen by Carotenoids via Ultrafast Superexchange Dynamics

A quantum chemical study of photochemical processes in the reaction Se + O2 → SeO2 with allowance for the spin orbit interaction

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