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PK a of ubiquinone, menaquinone, phylloquinone, plastoquinone, and rhodoquinone in aqueous solution.

ABSTRACT: Quinones can accept two electrons and two protons, and are involved in electron transfer and proton transfer reactions in photosynthetic reaction centers. To date, the pK a of these quinones in aqueous solution have not been reported. We calculated the pK a of the initial protonation (Q·- to QH·) and the second protonation (QH- to QH2) of 1,4-quinones using a quantum chemical approach. The calculated energy differences of the protonation reactions Q·- to QH· and QH- to QH2 in the aqueous phase for nine 1,4-quinones were highly correlated with the experimentally measured pK a(Q·-/QH·) and pK a(QH-/QH2), respectively. In the present study, we report the pK a(Q·-/QH·) and pK a(QH-/QH2) of ubiquinone, menaquinone, phylloquinone, plastoquinone, and rhodoquinone in aqueous solution.

SUBMITTER: Hasegawa R

PROVIDER: S-EPMC5500672 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature

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pK a of ubiquinone, menaquinone, phylloquinone, plastoquinone, and rhodoquinone in aqueous solution.

Hasegawa Ryo R Saito Keisuke K Takaoka Tomohiro T Ishikita Hiroshi H

Photosynthesis research 20170412 1-3

Quinones can accept two electrons and two protons, and are involved in electron transfer and proton transfer reactions in photosynthetic reaction centers. To date, the pK a of these quinones in aqueous solution have not been reported. We calculated the pK a of the initial protonation (Q·- to QH·) and the second protonation (QH- to QH2) of 1,4-quinones using a quantum chemical approach. The calculated energy differences of the prot ...[more]

PMID: 28405861

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