A viewpoint: Why chlorophyll a?

Lars Olof Björn, George C. Papageorgiou, Robert E. Blankenship, [unknown] Govindjee

    Forskningsoutput: TidskriftsbidragÖversiktsartikelPeer review


    Chlorophyll a (Chl a) serves a dual role in
    oxygenic photosynthesis: in light harvesting as well as in
    converting energy of absorbed photons to chemical energy.
    No other Chl is as omnipresent in oxygenic photosynthesis
    as is Chl a, and this is particularly true if we include Chl a2,
    (=[8-vinyl]-Chl a), which occurs in Prochlorococcus, as a
    type of Chl a. One exception to this near universal pattern
    is Chl d, which is found in some cyanobacteria that live in
    filtered light that is enriched in wavelengths [700 nm.
    They trap the long wavelength electronic excitation, and
    convert it into chemical energy. In this Viewpoint, we have
    traced the possible reasons for the near ubiquity of Chl a
    for its use in the primary photochemistry of Photosystem II
    (PS II) that leads to water oxidation and of Photosystem I
    (PS I) that leads to ferredoxin reduction. Chl a appears to
    be unique and irreplaceable, particularly if global scale
    oxygenic photosynthesis is considered. Its uniqueness is
    determined by its physicochemical properties, but there is
    more. Other contributing factors include specially tailored
    protein environments, and functional compatibility with
    neighboring electron transporting cofactors. Thus, the same
    molecule, Chl a in vivo, is capable of generating a radical
    cation at ?1 V or higher (in PS II), a radical anion at -1 V
    or lower (in PS I), or of being completely redox silent (in
    antenna holochromes).
    Sidor (från-till)85-98
    TidskriftPhotosynthesis Research
    StatusPublished - 2009

    Ämnesklassifikation (UKÄ)

    • Biologiska vetenskaper


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