On the Impossibility of an OH-Radical Model for Photosynthetic Water Oxidation / Über die Unmöglichkeit eines OH-Radikalmodells für die photosynthetische Wasseroxidation

1972 ◽  
Vol 27 (2) ◽  
pp. 172-176 ◽  
Author(s):  
Gerhard Vierke
Keyword(s):  
Kinetic Model ◽  
Water Oxidation ◽  
Photosynthetic Apparatus ◽  
Experimental Results ◽  
Oh Radicals ◽  
Oh Radical ◽  
Inherent Property ◽  
Evolving System ◽  
Photosynthetic Water Oxidation ◽  
Radical Model

If it is assumed that the oscillating O2 flash yield sequence of algae and chloroplasts predominantly reflects an inherent property of the O2 evolving system of the photosynthetic apparatus it is shown that the OH-radical model (O2 production by recombination of four OH radicals) is contradictory to the experimental results because it predicts an aperiodic O2 flash yield sequence.Several experimental facts already known strongly indicate that the OH-radical model is not consistent with the kinetic model for O2 evolution of KOK et al. either.

The pH dependence of OH radical formation in photo-electrochemical water oxidation with rutile TiO2 single crystals

2015 ◽  
Vol 17 (45) ◽  
pp. 30570-30576 ◽  
Author(s):  
Yukihiro Nakabayashi ◽  
Yoshio Nosaka
Keyword(s):  
Reaction Mechanism ◽  
Single Crystals ◽  
Alkaline Solution ◽  
Water Oxidation ◽  
Oxidation Process ◽  
Ph Dependence ◽  
Experimental Results ◽  
Radical Formation ◽  
Oh Radical ◽  
Rutile Tio2

The experimental results in photoelectrolysis with rutile (100) and (110) TiO2 single crystals support a plausible reaction mechanism that the surface Ti–O–O–Ti structure is an intermediate of water oxidation process, by which mechanism the O2 production becomes favorable in alkaline solution.

Nitrate and chloride formation in chloramination

1994 ◽  
Vol 30 (9) ◽  
pp. 101-110
Author(s):  
V. Diyamandoglu
Keyword(s):  
Kinetic Model ◽  
Analytical Method ◽  
Kinetic Data ◽  
Experimental Results ◽  
Mass Balances ◽  
Time Profiles ◽  
Slow Decay ◽  
Concentration Time ◽  
End Products ◽  
Chlorine Residuals

The formation of nitrate and chloride as end-products of chloramination (combined chlorination) was investigated at pH ranging between 6.9 and 9.6 at 25°C. The experimental results comprised concentration-time profiles of combined chlorine residuals along with nitrate and chloride. Nitrite, if present, was always below the detectibility limit of the analytical method used (25 ppb). Mass balances on chlorine species depicted that chloride formed during the slow decay of combined chlorine residuals does not account for all the chlorine lost. This substantiates the formation of other reaction end-products which are yet to be identified. A kinetic model for chloramination is proposed based on the kinetic data obtained in this study.

scholarly journals Photosynthetic water oxidation

FEBS Letters ◽  
1985 ◽  
Vol 189 (2) ◽  
pp. 258-262 ◽  
Author(s):  
Andrew N. Webber ◽  
Lee Spencer ◽  
Donald T. Sawyer ◽  
Robert L. Heath
Keyword(s):  
Water Oxidation ◽  
Photosynthetic Water Oxidation

scholarly journals Effect of alkaline pH on photosynthetic water oxidation and the association of extrinsic proteins with Photosystem Two

1989 ◽  
Vol 258 (2) ◽  
pp. 357-362 ◽  
Author(s):  
D J Chapman ◽  
J De Felice ◽  
K Davis ◽  
J Barber
Keyword(s):  
Water Splitting ◽  
Water Oxidation ◽  
Binding Sites ◽  
Partial Recovery ◽  
Alkaline Ph ◽  
Ph Values ◽  
Extrinsic Proteins ◽  
Reversible Phase ◽  
Photosynthetic Water Oxidation ◽  
Optimal Ph

Incubation of a membrane preparation enriched in Photosystem Two (PSII) at alkaline pH inhibited the water-splitting reactions in two distinct steps. Up to pH 8.5 the inhibition was reversible, whereas at higher alkalinities it was irreversible. It was shown that the reversible phase correlated with loss and rebinding of the 23 kDa extrinsic polypeptide. However, after mild alkaline treatments a partial recovery was possible without the binding of the 23 kDa polypeptide when the assay was at the optimal pH of 6.5 and in a medium containing excess Cl-. The irreversible phase was found to be closely linked with the removal of the 33 kDa extrinsic protein of PSII. Treatments with pH values above 8.5 not only caused the 33 kDa protein to be displaced from the PSII-enriched membranes, but also resulted in an irreversible modification of the binding sites such that the extrinsic 33 kDa protein could not reassociate with PSII when the pH was lowered to 6.5. The results obtained with these more extreme alkaline pH treatments support the notion that the 23 kDa protein cannot bind to PSII unless the 33 kDa protein is already bound. The differential effect of pH on the removal of the 23 kDa and 33 kDa proteins contrasted with the data of Kuwabara & Murata [(1983) Plant Cell Physiol. 24, 741-747], but this discrepancy was accounted for by the use of glycerol in the incubation media.

Preparation and properties of models for the photosynthetic water oxidation center: spin frustration in the manganese [Mn4O2(O2CR)7(pic)2]- anion

1991 ◽  
Vol 30 (18) ◽  
pp. 3486-3495 ◽  
Author(s):  
Eduardo. Libby ◽  
James K. McCusker ◽  
Edward A. Schmitt ◽  
Kirsten. Folting ◽  
David N. Hendrickson ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Spin Frustration ◽  
Photosynthetic Water Oxidation
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