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PHOTOSYNTHETIC NITRITE REDUCTION BY DITHIOERYTHRITOL AND THE EFFECT OF NITRITE ON ELECTRON TRANSPORT IN ISOLATED CHLOROPLASTS
Author(s) -
Spiller Hart,
Böger Peter
Publication year - 1977
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1977.tb07504.x
Subject(s) - nitrite , chemistry , nitrite reductase , ferredoxin , chloroplast , photosynthesis , photosystem i , electron transport chain , photosystem ii , chlorophyll , electron acceptor , oxygen , redox , photochemistry , nitrate , biochemistry , inorganic chemistry , enzyme , organic chemistry , gene
. Photosynthetic reduction of nitrite to ammonia with type C chloroplasts from the heterocont alga Bumilleriopsis filiformis was investigated using 3,6‐diaminodurene/ascorbate and 3,6‐diaminodurene/dithioerythritol (DAD/DTE) as electron donor couple. Rates approach 6–10 μmol NO ‐ 2 reduced/mg chlorophyll/h and are steady for up to 30 min. The presence of oxygen or NADP + only slightly diminished the rates of nitrite reduction obtained with DAD/DTE. Illuminated chloroplasts reduce oxygen in the presence of DAD/DTE at 135 μmol/mg chlorophyll/h without acceptor supplied. Photosynthetic oxygen uptake by this system in the presence of ferredoxin and NO ‐ 2 , however, is inhibited to 42% by nitrite reductase with concurrent nitrite reduction. NO ‐ 3 and NO ‐ 2 have no effect on photosystem I‐mediated NADP + reduction, NO ‐ 2 (10 m M ) inhibits ferricyanide‐mediated oxygen evolution to 72%. Also photosystem II reactions assayed e.g. with silicomolybdate are inhibited significantly by NO ‐ 2 (1 m M ), but only slightly by NO ‐ 3 . Nitrite reductase is inhibited by p ‐chloromercuribenzoate ( p CMB), and this inhibition is prevented by DTE. Results suggest that photosynthetic nitrite reduction can cope with low concentrations of either compound, provided relevant thiol groups are protected.