Action of some derivatives of 1,10-phenanthroline on electron transport in chloroplasts.
The effectiveness and the mode of inhibitory action of some derivatives of 1,10-phenanthroline and a few other substances on 2,6-dichlorophenolindophenol (DCIP) photoreduction and fluorescence induction at room temperature in spinach chloroplasts were compared in this paper. 4,7-Dimethyl-1,10-phenanthroline was the most potent inhibitor [pI50 (-log10 of molar concentration of inhibitor giving 50% inhibition), 5.9] examined, and 5-methyl-1,10-phenanthroline (pI50, 4.2) was as potent as 1,10-phenanthroline (pI50, 4.4), in the case of DCIP photoreduction. The order of inhibition by 4,7-dimethyl-1,10-phenanthroline (n=2) was different from that of 1,10-phenanthroline and 5-methyl-1,10-phenanthroline (n=1), under the experimental conditions used. Fluorescence induction was diminished by 4,7-dimethyl-1,10-phenanthroline or 5-methyl-1,10-phenanthroline with the same pattern as 1,10-phenanthroline, but the effective concentrations varied corresponding to the pI50 values for the inhibition of DCIP photoreduction. Metal ions which form a chelate complex with phenanthroline of high stability constant prevented the inhibition of both DCIP photoreduction and fluorescence induction. From these results, the structure-activity relations and the mode of inhibition of the photosynthetic electron transport chain by these reagents are discussed.
Satoh
K
K
Department of Biology, Faculty of Sciences, Okayama University, Okayama, Japan.
D015086:2,6-Dichloroindophenol / Q000378:metabolism*; D002614:Chelating Agents / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism*; D004579:Electron Transport / Q000187:drug effects*; D008027:Light; D008670:Metals / Q000737:chemistry; D010084:Oxidation-Reduction; D010618:Phenanthrolines / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D018724:Spinacia oleracea / Q000166:cytology / Q000378:metabolism
D002614:Chelating Agents; D008670:Metals; D010618:Phenanthrolines; D015086:2,6-Dichloroindophenol; C025205:1,10-phenanthroline