MedicGo
Light-induced changes of absorbance and electron spin resonance in small photosystem II particles.
Metadata
JournalBiochim. Biophys. ActaNot FoundDate
1975-Dec-11
Publication Type
Journal Article
Volume
1975-Dec-11 / 408 : 331-9
Author
Van Gorkom HJ , Pulles MP , Wessels JS
DoiPMIDMESH
Binding Sites
Chlorophyll
Chloroplasts
Darkness
Diuron
Electron Spin Resonance Spectroscopy
Ferricyanides
Hydrogen-Ion Concentration
Light
Photophosphorylation
Plants
Spectrophotometry
Spectrophotometry, Ultraviolet
Abstract
Photosystem II reaction center components have been studied in small system II particles prepared with digitonin. Upon illumination the reduction of the primary acceptor was indicated by absorbance changes due to the reduction of a plastoquinone to the semiquinone anion and by a small blue shifts of absorption bands near 545 nm (C550) and 685 nm. The semiquinone to chlorophyll ratio was between 1/20 and 1/70 in various preparations. The terminal electron donor in this reaction did not cause large absorbance changes but its oxidized form was revealed by a hitherto unknown electron spin resonance (ESR) signal, which had some properties of the well-known signal II but a linewidth and g-value much nearer to those of signal I. Upon darkening absorbance and ESR changes decayed together in a cyclic or back reaction which was stimulated by 3-(3,4 dichlorophenyl)-1,1-dimethylurea. The donor could be oxidized by ferricyanide in the dark. Illumination in the presence of ferricyanide induced absorbance and ESR changes, rapidly reversed upon darkening, which may be ascribed to the oxidation of a chlorophyll a dimer, possibly the primary electron donor of photosystem II. In addition an ESR signal with 15 to 20 gauss linewidth and a slower dark decay was observed, which may have been caused by a secondary donor.
Fav
Like
Download
Share
Export
Cite
B
Biochim. Biophys. ActaBiochimica et biophysica acta
Metadata
Location
From

No Data

© 2017 - 2020 Medicgo
Powered by some medical students