Effects of various buffers, 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea (DCMU) and NaN3on menadione mediated photophosphorylation in isolated chloroplasts
作者:
M. USAMAH DURAINI,
LEIF HAMLIN,
JAN‐ERIC TILLBERG,
期刊:
Physiologia Plantarum
(WILEY Available online 1980)
卷期:
Volume 48,
issue 1
页码: 9-14
ISSN:0031-9317
年代: 1980
DOI:10.1111/j.1399-3054.1980.tb03211.x
出版商: Blackwell Publishing Ltd
关键词: Chloroplasts;(3‐dichlorophenyl)‐1,1‐dimethylurea (DCMU);2‐methyl‐1,4‐naphtoquinone (menadione);photophosphorylation;sodiumazide
数据来源: WILEY
摘要:
AbstractThe effects of DCMU and NaN3were studied on menadione‐mediated photophosphorylation in broken spinach chloroplasts kept in low oxygen tension in Tricine or HEPES buffers at either high or reduced irradiances. – (A) At high irradiance (131 W. m−2) andabsenceof NaN3the ATP formation was inhibited by DCMU regardless of the type of buffer used. – (B) At high irradiance andpresenceof NaN3some concentrations of DCMU stimulated, whilst others inhibited the ATP formation in a HEPES buffer. The ATP formation was predominantly inhibited by DCMU in a Tricine buffer. – (C) At reduced irradiance (57 W. m−2) the chloroplasts in a HEPES buffer were almost insensitive towards DCMU both in the presence and absence of NaN3. – (D) Chloroplasts in a Tricine buffer were slightly stimulated in their ATP formation by DCMU at reduced irradiance either with or without the presence of NaN3in the experimental medium. When menadione acts as a terminal electron acceptor, oxygen is consumed on its reoxidation. The results indicate that this process may occur with oxygen released by the splitting of water as the main oxidant. – The data also demonstrate the importance of caution when selecting buffering substances as well as when choosing light intensities for experiments on photophosphorylation
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