EurekaMag.com logo
+ Translate

Spectral characterization in the uv region of the precursor of photosynthetically evolved oxygen in isolated trypsinized chloroplasts


, : Spectral characterization in the uv region of the precursor of photosynthetically evolved oxygen in isolated trypsinized chloroplasts. Biochimica et Biophysica Acta 722(1): 1-11

The reaction mechanism of the water-spliting enzyme system Y was analyzed by measurements of UV absorption changes induced by a flash train in dark-adapted spinach chloroplasts. To eliminate processes which give rise to interfering absorption changes with a binary oscillation, mildly trypsizined chloroplasts were applied which are disconnected from the secondary plastoquinone acceptor B, but are able to evolve O2, provided that K3Fe(CN)6 is used as electron acceptor. The extent of the relaxation kinetics of the 320 nm absorption change accomplished within 5 ms oscillates with a periodicity of 4 in phase with the O2 yield as a function of the number of the flash in the train. The difference spectra of the difference between the initial amplitudes and those remaining after a 4.5 ms dark period, referred to as .**GRAPHIC**. exhibit pronounced bands peaking around 320 nm (positive) and 270 nm (negative). The extent oscillates in the flash train. It is at a maximum for the absorption change differences induced by the 3rd flash, .**GRAPHIC**. Taking into account the fact that the 1st flash of the train does not yield O2, whereas the O2 production is at a maximum due to the 3rd flash, the difference of .**GRAPHIC**. as a function of wavelength is interpreted as the difference spectrum of the precursor of molecular O2 in system Y. The spectrum exhibits a band peaking around 320 nm. The precursor is referred to as Y-320. A molecular model proposed for the mechanism of photosynthetic water oxidation is discussed.

(PDF 0-2 workdays service)

Accession: 006459590

Submit PDF Full Text: Here


Submit PDF Full Text

No spam - Every submission is manually reviewed

Due to poor quality, we do not accept files from Researchgate

Submitted PDF Full Texts will always be free for everyone
(We only charge for PDFs that we need to acquire)

Select a PDF file:
Close
Close

Related references

Klughammer, C.; Schreiber, U., 1991: Analysis of light induced absorbance changes in the near ir spectral region i. characterization of various components in isolated chloroplasts. Light-induced absorbance changes in the near-infrared (NIR) spectral region (700-950 nm) are analyzed in isolated spinach chloroplasts using pulsed light-emitting diodes as modulated measuring light sources. With chloroplasts under coupled conditi...

Klughammer, C.; Schreiber, U., 1991: Analysis of light-induced absorbance changes in the near-infrared spectral region. I. Characterization of various components in isolated chloroplasts. Light-induced absorbance changes in the near-IR spectral region (700-950 nm) were analysed in isolated spinach chloroplasts using pulsed light-emitting diodes as modulated measuring light sources. With chloroplasts under coupled conditions the lig...

Thomas, J.B.; Goedheer, J.C.; Vandenberg, J.W., 1963: Time Course Of Spectral Shifts In The Red-Absorption Band And Loss Of Photochemical Oxygen-Liberating Capacity In Isolated Aspidistra Chloroplasts. Biochimica et Biophysica Acta 75: 333-339

Renger G.; Weiss W., 1982: The detection of intrinsic 320 nanometer absorption changes reflecting the turnover of the water splitting enzyme system y which leads to oxygen formation in trypsinized chloroplasts. Febs Letters 137(2): 217-221

Bouges, B., 1971: Action of low concentrations of hydroxylamine on oxygen evolved by Chlorella and spinach chloroplasts. Biochimica et Biophysica Acta 234(1): 103-112

Stern, B.K., 1963: Isotopic Composition Of The Oxygen Evolved By Illuminated Spinach Chloroplasts And Grana With K2c18o3 As A Tracer. Biochimica et Biophysica Acta 75: 340-348

Fufsler, T.P.; Castelfranco, P.A.; Wong, Y.S.ing, 1984: Formation of Mg-containing chlorophyll precursors from protoporphyrin IX, d-aminolevulinic acid, and glutamate in isolated, photosynthetically competent, developing chloroplasts. Plant Physiology 74: 8-33

Fufsler, T.P.; Castelfranco, P.A.; Wong, Y.S., 1984: Formation of Mg-Containing Chlorophyll Precursors from Protoporphyrin IX, delta-Aminolevulinic Acid, and Glutamate in Isolated, Photosynthetically Competent, Developing Chloroplasts. Intact developing chloroplasts isolated from greening cucumber (Cucumis sativus L. var Beit Alpha) cotyledons were found to contain all the enzymes necessary for the synthesis of chlorophyllide. Glutamate was converted to Mg-protoporphyrin IX (mon...

Fufsler, T.P.; Castelfranco, P.A.; Wong, Y.S., 1984: Formation of Mg-containing chlorophyll precursors from protoporphyrin IX, delta -aminolevulinic acid, and glutamate in isolated, photosynthetically competent, developing chloroplasts. From Beit Alpha cucumber cotyledons.

Hejl, A.M.; Bormann, T.; Koster, K.L.; Einhellig, F.A., 1993: Effect of six sesquiterpene lactones on oxygen uptake in isolated mitochondria and oxygen evolution in isolated chloroplasts. Plant Physiology (Rockville) 102(1 SUPPL ): 114