Photoreduction of pheophytin in photosystem II of the whole cells of green algae and cyanobacteria

V. V. Klimov, S. I. Allakhverdiev, V. G. Ladygin

    Research output: Contribution to journalArticlepeer-review

    29 Citations (Scopus)

    Abstract

    Photoreduction of Pheophytin 'a' (Pheo) accompanied by a decrease in the chlorophyll fluorescence yield is observed in photosystem II (PS II) of the whole cells of green algae Chlamydomonas reinhardii (a wild type and a mutant lacking both photosystem I and chlorophyll 'b'), Chlorella pyrenoidosa, Scenedesmus obliquus and cyanobacteria Phormidium laminosum, Anabaena variabilis and Cynechococcus elongatus under anaerobic conditions created by means of the glucose-glucoseoxidase-catalase. The photoreaction is activated by the addition of 1 μM CCCP, inhibited by 10 μM DCMU and reactivated upon subsequent addition of either ascorbate or dithionite. Oxidized NADP, benzyl viologen and methyl viologen accelerate dark oxidation of the reduced Pheo indicating that they are able to accept an electron from {Mathematical expression} in PS II. The data on both photoreduction of Pheo in the intact cells in the absence of exogenous reductants, when electron donation to reaction centers of PS II occurs only from water, and the inhibition of this photoreaction by DCMU, show that the Pheo photoreduction is sensitized by the reaction centers of PS II and probably occurs as a result of the electron donation from the water-splitting system being in the state S3, to {Mathematical expression} producing the long-lived state {Mathematical expression} and O2.

    Original languageEnglish
    Pages (from-to)355-363
    Number of pages9
    JournalPhotosynthesis research
    Volume10
    Issue number3
    DOIs
    Publication statusPublished - Jan 1 1986

    Keywords

    • NADP reduction (Algae cells)
    • Pheophytin
    • Photosystem II
    • Reaction center
    • Water splitting

    ASJC Scopus subject areas

    • Biochemistry
    • Plant Science
    • Cell Biology

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