Metallo-oxidase Enzymes: Design of their Active Sites

2011 ◽  
Vol 64 (3) ◽  
pp. 231 ◽  
Author(s):  
Zhiguang Xiao ◽  
Anthony G. Wedd
Keyword(s):  
Metal Ions ◽  
Active Sites ◽  
Specific Binding ◽  
Large Family ◽  
Outer Sphere ◽  
Transition Metal Ions ◽  
Substrate Oxidation ◽  
Cellular Functions ◽  
Domains Of Life ◽  
Low Valent

Multi-copper oxidases are a large family of enzymes prevalent in all three domains of life. They couple the one-electron oxidation of substrate to the four-electron reduction of dioxygen to water and feature at least four Cu atoms, traditionally divided into three sites: T1, T2, and (binuclear) T3. The T1 site catalyzes substrate oxidation while a trinuclear cluster (comprising combined T2 and T3 centres) catalyzes the reduction of dioxygen. Substrate oxidation at the T1 Cu site occurs via an outer-sphere mechanism and consequently substrate specificities are determined primarily by the nature of a substrate docking/oxidation (SDO) site associated with the T1 Cu centre. Many of these enzymes ‘moonlight’, i.e. display broad specificities towards many different substrates and may have multiple cellular functions. A sub-set are robust catalysts for the oxidation of low-valent transition metal ions such as FeII, CuI, and MnII and are termed ‘metallo-oxidases’. They play essential roles in nutrient metal uptake and homeostasis, with the ferroxidase ceruloplasmin being a prominent member. Their SDO sites are tailored to facilitate specific binding and facile oxidation of these low-valent metal ions and this is the focus of this review.

Promoted photocarriers transfer and increased active sites for optimal CO2–to–CH4 photoconversion via the modification of atomically dispersed transition metal ions in CdZnS nanocrystals

2021 ◽  
Author(s):  
Haibo Huang ◽  
Hui-Ying Zhang ◽  
Feng-Ying Cai ◽  
Y Li ◽  
Jian Lü ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Conversion Rate ◽  
Active Sites ◽  
Transition Metal Ions ◽  
Co2 Photoreduction

Atomically dispersed transition metal ions doped CdZnS nanocrystals were synthesized to delicately tune the selectivity of CO2 photoreduction towards CH4, by which the CZS–Cu2+ achieved an excellent CO2–to–CH4 conversion rate...

scholarly journals CREATION A SORPTION MATERIAL FOR THE EXTRACTION OF METAL IONS FROM AQUEOUS SOLUTIONS

2021 ◽  
Vol 3 ◽  
pp. 97-107
Author(s):  
N.М. Zhunusbekova ◽  
◽  
Т.К. Iskakova ◽  
N.S. Chinibayeva ◽  
G.К. Kussainova ◽  
...  
Keyword(s):  
Acrylic Acid ◽  
Metal Ions ◽  
Polymer Composites ◽  
Contact Lenses ◽  
Specific Binding ◽  
Ion Pairs ◽  
Three Dimensional ◽  
Transition Metal Ions ◽  
Interpenetrating Networks ◽  
Soft Contact Lenses

The presence of a three-dimensional hydrophilic network structure ensures the uniqueness and wide practical application of hydrogels in industry, medicine, agriculture, etc. On their basis, soft contact lenses, dressings, superabsorbents, catalysts, soil structuring agents, preventing root drying and improving plant survival, have been created. The aimof this work is to synthesize new water-swellable polymer composites by combining monomer units of various natures based on acrylic acid and agar-agar with imidazole, differing in hydrophilic-hydrophobic balance. Results and discussion: The synthesis of new double and ternary polymer composites based on acrylic acid and agar-agar with imidazole was carried out, their physicochemical and complex-forming properties with transition metal ions in an aqueous medium were investigated. Comparative analysis showed that the complexation of interpenetrating networks with FeCl3 is more pronounced than with CoCl2. This fact can be associated with the difficulty of introducing a cobalt ion into the ligand plane during the formation of a metal complex, which further affects the binding to the functional groups of the network. The specific binding of the obtained polymer composites with metal salts was shown, which is carried out through the formation of ion pairs with the participation of counterions and coordination-unsaturated metals, which make the main contribution to the formation of extracomplexes and are responsible for the coordination of oxygen-containing ligands.

scholarly journals Polymer Catalysts Imprinted with Metal Ions as Biomimics of Metalloenzymes

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Joanna Czulak ◽  
Anna Jakubiak-Marcinkowska ◽  
Andrzej Trochimczuk
Keyword(s):  
Metal Ions ◽  
Molecularly Imprinted Polymers ◽  
Active Sites ◽  
Suspension Polymerization ◽  
Transition Metal Ions ◽  
Sorption Process ◽  
Surface Imprinting ◽  
Molecularly Imprinted ◽  
Functional Monomers ◽  
Surface Imprinting Technique

This work presents the preparation and properties of molecularly imprinted polymers (MIPs) with catalytic centers that mimic the active sites of metalloenzymes. The MIP synthesis was based on suspension polymerization of functional monomers (4-vinylpyridine and acrylonitrile) with trimethylolpropane trimethacrylate as a crosslinker in the presence of transition metal ions and 4-methoxybenzyl alcohol as a template. Four metal ions have been chosen for imprinting from among the microelements that are the most essential in the native enzymes: Cu2+, Co2+, Mn2+, and Zn2+. To prepare catalysts, the required loading of metal ions was obtained during sorption process. The catalysts imprinted with Cu2+, Co2+, and Zn2+were successfully used for hydroquinone oxidation in the presence of hydrogen peroxide. The Mn2+-imprinted catalyst showed no activity due to the insufficient metal loading. Cu2+MIP showed the highest efficiency. In case of Cu- and Co-MIP catalysts, their activity was additionally increased by the use of surface imprinting technique.

scholarly journals Open-framework aluminophosphates: Synthesis, characterization and transition metal modifications

2005 ◽  
Vol 70 (3) ◽  
pp. 371-391 ◽  
Author(s):  
Nevenka Rajic
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Active Sites ◽  
Transition Metal Ions ◽  
Isomorphous Substitution ◽  
Synthesis Conditions ◽  
Open Framework ◽  
Wide Range ◽  
Redox Ability ◽  
Compositional Diversity

This review is a brief summary of open-framework aluminophosphates and their transition metal-substituted modifications. The materials exhibit structural and compositional diversity, as well as a wide range of pore openings, which are crystallographically ordered and can be tuned by an appropriate choice of synthesis conditions. The diameters of the apertures, cages and channels fall in the range of 0.4 to about 1.5 nm, which recommends aluminophosphates for a novel area of application-nanocatalysis. Isomorphous substitution of the framework elements by transition metal ions which possess redox ability creates active sites inside the aluminophosphate lattice and opens routes towards shape selective bi-functional catalysis. In order to obtain an insight into the location of the transition metal ions, different characterization techniques have to be used.

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