Light-induced turnover of chloroplast cytochrome b-559 in the presence of N-methylphenazonium methosulphate.
In the presence of 0.1-5 muM N-methylphenazonium methosulphate approx. 50-70% oxidation of cytochrome b-559 can be induced by far-red light. The oxidation is best observed with long wavelength far-red light (732 nm) of moderate intensities (approx. 10(4) ergs/cm2 per s) and is reversed by subsequent illumination with red light. Concentrations of N-methylphenazonium methosulphate above 5 muM are inhibitory probably due to cyclic electron flow. The far-red oxidation is inhibited by low concentrations of the plastoquinone antagonist 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone, while 3-(3,4-dichlorophenyl)-1,1-dimethylurea inhibits red light reduction and increases the amplitude of far-red oxidation. The effect of N-methylphenazonium methosulphate is mimicked by N-methyl-phenazonium ethosulphate, but not by pyocyanine or diaminodurene. Low concentrations (2-3 muM) of N-methylphenazonium methosulphate also stimulate a 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone-inhibitable red light reduction of cytochrome f.
D002734:Chlorophyll / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism* / Q000528:radiation effects; D003580:Cytochromes / Q000378:metabolism* / Q000528:radiation effects; D003991:Dibromothymoquinone / Q000494:pharmacology; D004237:Diuron / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005292:Ferricyanides / Q000494:pharmacology; D008773:Methylphenazonium Methosulfate / Q000494:pharmacology*; D010084:Oxidation-Reduction; D010619:Phenazines / Q000494:pharmacology*; D010655:Phenylenediamines / Q000494:pharmacology; D011710:Pyocyanine / Q000494:pharmacology
D003580:Cytochromes; D005292:Ferricyanides; D010619:Phenazines; D010655:Phenylenediamines; D002734:Chlorophyll; D003991:Dibromothymoquinone; D008773:Methylphenazonium Methosulfate; C005158:diaminodurene; D004237:Diuron; D011710:Pyocyanine