The Energy State and Structure of Isolated Chloroplasts: The Oxidative Reactions Involving the Water-Splitting Step of Photosynthesis

Abstract NADP+ reduction in isolated chloroplasts of spinach by photosystem I at the expense of various artificial donor systems is not inhibited by the plastoquinone antagonist dibromothymoquinone. The coupled ATP formation in such photoreductions is attributed to an artificial energy conserving site, i. e. a proton liberation during oxidation of the donor at the inner surface of the thylakoid membrane. Some donor systems for photosystem I are stimulated by uncouplers whereas others are not. The stimulation shows no correlation to the efficiency of the coupled photophosphorylation. Instead a correlation of the stimulation by uncouplers to the presence of an acidic OH-group in the donor molecule is seen. The uncoupler effect is therefore not explained by a release of electron transport control by the high energy state but rather by a pH-dependent distribution of the donor compound across the membrane. This is supported by the properties of donor systems in sonicated chloroplast particles with external oxidation sites of photosystem I.

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Proton Transport and the High-Energy State in Isolated Chloroplasts

Membrane Transport in Plants ◽

10.1007/978-3-642-65986-7_36 ◽

1974 ◽

pp. 256-263 ◽

Cited By ~ 1

Author(s):

A. B. Hope ◽

W. S. Chow

Keyword(s):

Proton Transport ◽

Energy State ◽

High Energy ◽

High Energy State ◽

Isolated Chloroplasts

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Light-Dependent Interactions of Phenazine Methosulfate with 3-(3,4-Dichlorophenyl)-1,1-dimethylurea-Poisoned Chloroplasts

Zeitschrift für Naturforschung C ◽

10.1515/znc-1976-11-1217 ◽

1976 ◽

Vol 31 (11-12) ◽

pp. 722-729 ◽

Cited By ~ 1

Author(s):

Bernd Schmidt ◽

Hans Rurainski

Keyword(s):

Chlorophyll Fluorescence ◽

Transient Absorption ◽

Energy State ◽

Spectral Characteristics ◽

High Energy ◽

Phenazine Methosulfate ◽

Experimental Conditions ◽

Absorption Change ◽

High Energy State ◽

Isolated Chloroplasts

Abstract The chlorophyll fluorescence of isolated chloroplasts in the presence of phenazine methosulfate (PMS) and 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) can be quenched in a light-dependent reaction. This phenomenan has been studied and the following observations were made: 1. Quenching occurs under non-phosphorylating conditions and is stimulated by Mg2+ ions. 2. Under the same conditions, a light-dependent, Mg2+ stimulated transient decrease of absorp tion at 388 nm is observed which shows the spectral characteristics of PMS. 3. PMS is reversibly bound to chloroplasts. Under the experimental conditions used, binding amounts to as much as 0.5 mol PMS/mol chlorophyll. 4. Some uncouplers of photophosphorylation such as carbonylcyanide-m-chlorophenylhydrazon (CCCP) and atebrin analog abolish quenching, transient absorption change and binding of PMS. Others, such as methylamine, ammonia, gramicidin and nigericin do not. It is suggested that fluorescence quenching, transient absorption change and binding of PMS are causally related. The concept, postulated by others, that a high-energy state of the chloroplast membrane is involved in the fluorescence lowering is questioned.

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Inhibition of Photosystem II andChlorellaGrowth by 1-(m-t-butylacetamidophenyl)-3-methyl-3-methoxy urea

Weed Science ◽

10.1017/s0043174500043885 ◽

1979 ◽

Vol 27 (2) ◽

pp. 232-234 ◽

Cited By ~ 1

Author(s):

J. A. Swader ◽

Celestia M. Howe

Keyword(s):

Photosystem Ii ◽

Water Splitting ◽

Electron Donor ◽

Photosystem I ◽

Electron Acceptor ◽

Spinacia Oleracea ◽

Chlorella Sorokiniana ◽

Phenylurea Herbicide ◽

Isolated Chloroplasts

The experimental herbicide R-24191 [1-(m-t-butylacetamidophenyl)-3-methyl-3-methoxy urea] inhibited growth ofChlorella sorokinianaShihira and Kraus, O2evolution during CO2fixation byChlorellaand isolated leaf cells of spinach (Spinacia oleraceaL. ‘Winter Bloomsdale 769′), the photoreduction of NADP by isolated chloroplasts using water or hydroxylamine as the electron donor, the photoreduction of 2,6-dichloroindophenol by isolated chloroplasts, and O2uptake by isolated chloroplasts using paraquat (1,1′-dimethyl-4,4′-bipyridinium ion) as the electron acceptor. The phenylurea herbicide had no effect on the last reaction when ascorbate plus 2,6-dichloroindophenol were used as the electron donor. The results indicate that the site of the phenylurea inhibition was in photosystem II between water-splitting and photosystem I.

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High-resolution EM study of submicrometer-grained Al-Mg solid solution alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100138993 ◽

1995 ◽

Vol 53 ◽

pp. 524-525

Author(s):

Z. Horita ◽

D. J. Smith ◽

M. Furukawa ◽

M. Nemoto ◽

R. Z. Valiev ◽

...

Keyword(s):

Electron Microscopy ◽

Solid Solution ◽

High Resolution ◽

Grain Boundaries ◽

Energy State ◽

High Energy ◽

Grain Structure ◽

Boundary Structure ◽

Solid Solution Alloy ◽

Average Grain Size

It is possible to produce metallic materials with submicrometer-grained (SMG) structures by imposing an intense plastic strain under quasi-hydrostatic pressure. Studies using conventional transmission electron microscopy (CTEM) showed that many grain boundaries in the SMG structures appeared diffuse in nature with poorly defined transition zones between individual grains. The implication of the CTEM observations is that the grain boundaries of the SMG structures are in a high energy state, having non-equilibrium character. It is anticipated that high-resolution electron microscopy (HREM) will serve to reveal a precise nature of the grain boundary structure in SMG materials. A recent study on nanocrystalline Ni and Ni3Al showed lattice distortion and dilatations in the vicinity of the grain boundaries. In this study, HREM observations are undertaken to examine the atomic structure of grain boundaries in an SMG Al-based Al-Mg alloy.An Al-3%Mg solid solution alloy was subjected to torsion straining to produce an equiaxed grain structure with an average grain size of ~0.09 μm.

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Advances in Photoelectrochemical Water Splitting

10.1039/9781782629863 ◽

2018 ◽

Cited By ~ 2

Keyword(s):

Water Splitting ◽

Photoelectrochemical Water Splitting

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Photoelectrochemical Water Splitting

10.1039/9781849737739 ◽

2013 ◽

Cited By ~ 39

Keyword(s):

Water Splitting ◽

Photoelectrochemical Water Splitting

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Electrochemical and photoelectrochemical water splitting with a CoOx catalyst prepared by flame assisted deposition

Dalton Transactions ◽

10.1039/c9dt03983j ◽

2020 ◽

Vol 49 (3) ◽

pp. 588-592 ◽

Cited By ~ 1

Author(s):

Fusheng Li ◽

Ziqi Zhao ◽

Hao Yang ◽

Dinghua Zhou ◽

Yilong Zhao ◽

...

Keyword(s):

Cobalt Oxide ◽

Water Splitting ◽

Water Oxidation ◽

Oxide Catalyst ◽

Photoelectrochemical Water Splitting ◽

Deposition Method ◽

Photoelectrochemical Water Oxidation

A cobalt oxide catalyst prepared by a flame-assisted deposition method on the surface of FTO and hematite for electrochemical and photoelectrochemical water oxidation, respectively.

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A novel ligand with –NH2 and –COOH-decorated Co/Fe-based oxide for an efficient overall water splitting: dual modulation roles of active sites and local electronic structure

Catalysis Science & Technology ◽

10.1039/d0cy01109f ◽

2020 ◽

Vol 10 (18) ◽

pp. 6266-6273

Author(s):

Yalan Zhang ◽

Zebin Yu ◽

Ronghua Jiang ◽

Jung Huang ◽

Yanping Hou ◽

...

Keyword(s):

Electronic Structure ◽

Water Splitting ◽

Energy Demand ◽

Active Sites ◽

Electrode Materials ◽

Global Energy ◽

Overall Water Splitting ◽

Local Electronic Structure ◽

Electrochemical Water Splitting

Excellent electrochemical water splitting with remarkable durability can provide a solution to satisfy the increasing global energy demand in which the electrode materials play an important role.

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