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.

The structure–activity correlation of bifunctional MnO2 polymorphoric and MoS2-based heterostructures: a highly efficient, robust electrochemical water oxidation and reduction reaction catalyst in alkaline pH

2021 ◽  
Vol 5 (4) ◽  
pp. 1148-1157
Author(s):  
Saikat Bolar ◽  
Subhasis Shit ◽  
Prakas Samanta ◽  
Naresh Chandra Murmu ◽  
Tapas Kuila
Keyword(s):  
Water Splitting ◽  
Oxidation State ◽  
Water Oxidation ◽  
Reduction Reaction ◽  
Alkaline Ph ◽  
Highly Efficient ◽  
Average Oxidation State ◽  
Structure Activity ◽  
Splitting Process

Phase controlled heterostructure derived from polymorphic MnO2 and MoS2 emerged as an advanced electrocatalyst. The decreased average oxidation state and layered interaction within the heterostructure significantly monitored water splitting process.

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

2020 ◽  
Vol 49 (3) ◽  
pp. 588-592 ◽  
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.

scholarly journals Laccases: Versatile Biocatalysts for the Synthesis of Heterocyclic Cores

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3719
Author(s):  
Ana Catarina Sousa ◽  
Lígia O. Martins ◽  
M. Paula Robalo
Keyword(s):  
Membered Ring ◽  
Low Molecular Weight ◽  
Redox Potentials ◽  
Redox Mediators ◽  
Multicopper Oxidases ◽  
Phenothiazine Derivatives ◽  
Ph Values ◽  
Electron Shuttles ◽  
Specific Oxidation ◽  
Optimal Ph

Laccases are multicopper oxidases that have shown a great potential in various biotechnological and green chemistry processes mainly due to their high relative non-specific oxidation of phenols, arylamines and some inorganic metals, and their high redox potentials that can span from 500 to 800 mV vs. SHE. Other advantages of laccases include the use of readily available oxygen as a second substrate, the formation of water as a side-product and no requirement for cofactors. Importantly, addition of low-molecular-weight redox mediators that act as electron shuttles, promoting the oxidation of complex bulky substrates and/or of higher redox potential than the enzymes themselves, can further expand their substrate scope, in the so-called laccase-mediated systems (LMS). Laccase bioprocesses can be designed for efficiency at both acidic and basic conditions since it is known that fungal and bacterial laccases exhibit distinct optimal pH values for the similar phenolic and aromatic amines. This review covers studies on the synthesis of five- and six-membered ring heterocyclic cores, such as benzimidazoles, benzofurans, benzothiazoles, quinazoline and quinazolinone, phenazine, phenoxazine, phenoxazinone and phenothiazine derivatives. The enzymes used and the reaction protocols are briefly outlined, and the mechanistic pathways described.

scholarly journals Au decorated BiVO4 inverse opal for efficient visible light driven water oxidation

RSC Advances ◽  
2021 ◽  
Vol 11 (15) ◽  
pp. 8751-8758
Author(s):  
Xiaonong Wang ◽  
Xiaoxia Li ◽  
Jingxiang Low
Keyword(s):  
Visible Light ◽  
Water Splitting ◽  
Water Oxidation ◽  
Inverse Opal ◽  
Photocatalytic Water Splitting ◽  
Visible Light Driven

Photocatalytic water splitting provides an effective way to prepare hydrogen and oxygen.

Iron and Nitrogen Co-doped CoSe2 Nanosheet Arrays for Robust Electrocatalytic Water Oxidation

2021 ◽  
Author(s):  
Di Li ◽  
Yingying Xing ◽  
Changjian Zhou ◽  
Yikai Lu ◽  
Shengjie Xu ◽  
...  
Keyword(s):  
Water Splitting ◽  
Water Oxidation ◽  
Energy Barrier ◽  
Large Scale ◽  
Scale Production ◽  
Reaction Energy ◽  
Large Scale Production ◽  
Nanosheet Arrays ◽  
Production Of Hydrogen ◽  
Co Doped

The high reaction energy barrier of the oxygen evolution reaction (OER) extremely reduces the efficiency of water splitting, which is not conducive to large-scale production of hydrogen. Due to the...

Visible light-driven novel g-C3N4/NiFe-LDH composite photocatalyst with enhanced photocatalytic activity towards water oxidation and reduction reaction

2015 ◽  
Vol 3 (36) ◽  
pp. 18622-18635 ◽  
Author(s):  
Susanginee Nayak ◽  
Lagnamayee Mohapatra ◽  
Kulamani Parida
Keyword(s):  
Photocatalytic Activity ◽  
Composite Materials ◽  
Visible Light ◽  
Water Splitting ◽  
Visible Light Irradiation ◽  
Water Oxidation ◽  
Reduction Reaction ◽  
Light Irradiation ◽  
Composite Photocatalyst ◽  
Visible Light Driven

Dispersion of exfoliated CN over the surface of exfoliated LDH composite materials, and its photocatalytic water splitting under visible-light irradiation.

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