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Effects of 2,5‐Dibromo‐3‐methyl‐6‐isopropyl‐ p ‐benzoquinone (DBMIB) on Light Induced and Glycolytic Phosphate Uptake in Scenedesmus
Author(s) -
SUNDBERG INGRID,
TILLBERG JANERIC,
BJÖRKLUND GUN
Publication year - 1976
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1976.tb04874.x
Subject(s) - dcmu , photophosphorylation , plastoquinone , chemistry , photosynthesis , biochemistry , chloroplast , photosystem ii , thylakoid , gene
The effects of DBMIB on photophosphorylation and glycolysis in Scenedesmus obtusiusculus Chod. were investigated by measuring the uptake of inorganic phosphate. To analyze the effects of DBMIB on the different energy coupling possibilities in open chain and cyclic photophosphorylation, DBMIB was given to the algae in narrow concentration intervals between 10 −6 M to 10 −4 M , either alone, or in combination with DCMU (3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea) or desaspidin. DBMIB inhibits non‐cyclic as well as cyclic photophosphorylation in Scenedesmus. However, the DCMU resistant photophosphorylation reactions are less sensitive to DBMIB than the open chain photophosphorylating system in non‐DCMU treated cells. Low concentrations of DBMIB even released a part of the DCMU inhibition. Experiments with combinations of DBMIB and desaspidin also indicated that cyclic photophosphorylation is less sensitive to DBMIB than non‐cyclic. The inhibition of DCMU resistant cyclic phosphorylation by DBMIB, which is a competitive inhibitor of quinones, indicated a participation of plastoquinones in this type of energy coupling as well as in the non‐cyclic and DCMU‐sensitive processes. The cyclic and the non‐cyclic photophosphorylation pathways probably use different parts of the plastoquinone pool. For the purpose of the experiments, it was necessary to produce data for the effect of DBMIB (10 −6 –10 −4 M ) on glycolysis. The highest concentration gave 50% inhibition.