scholarly journals Identification and Biochemical Characterization ofArabidopsis thalianaSulfite Oxidase

2001 ◽  
Vol 276 (50) ◽  
pp. 46989-46994 ◽  
Author(s):  
Thomas Eilers ◽  
Günter Schwarz ◽  
Henner Brinkmann ◽  
Christina Witt ◽  
Tim Richter ◽  
...  
Keyword(s):  
Biochemical Characterization ◽  
Sulfite Oxidase ◽  
Molybdenum Cofactor ◽  
Active Centers ◽  
Oxidase Gene ◽  
Cell Extracts ◽  
Redox Active ◽  
Wide Range ◽  
Heme Domain ◽  
Molybdenum Enzyme

In mammals and birds, sulfite oxidase (SO) is a homodimeric molybdenum enzyme consisting of an N-terminal heme domain and a C-terminal molybdenum domain (EC1.8.3.1). In plants, the existence of SO has not yet been demonstrated, while sulfite reductase as part of sulfur assimilation is well characterized. Here we report the cloning of a plant sulfite oxidase gene fromArabidopsis thalianaand the biochemical characterization of the encoded protein (At-SO). At-SO is a molybdenum enzyme with molybdopterin as an organic component of the molybdenum cofactor. In contrast to homologous animal enzymes, At-SO lacks the heme domain, which is evident both from the amino acid sequence and from its enzymological and spectral properties. Thus, among eukaryotes, At-SO is the only molybdenum enzyme yet described possessing no redox-active centers other than the molybdenum. UV-visible and EPR spectra as well as apparentKmvalues are presented and compared with the hepatic enzyme. Subcellular analysis of crude cell extracts showed that SO was mostly found in the peroxisomal fraction. In molybdenum cofactor mutants, the activity of SO was strongly reduced. Using antibodies directed against At-SO, we show that a cross-reacting protein of similar size occurs in a wide range of plant species, including both herbacious and woody plants.

Recent Applications of Rare Earth Complexes in Photoredox Catalysis for Organic Synthesis

2021 ◽  
Vol 25 ◽  
Author(s):  
Alexis Prieto ◽  
Florian Jaroschik
Keyword(s):  
Rare Earth ◽  
Lewis Acids ◽  
Rare Earth Complexes ◽  
Photoredox Catalysis ◽  
Organic Transformations ◽  
New Paradigm ◽  
Active Centers ◽  
Redox Active ◽  
Wide Range ◽  
Made In

: In recent years, photoredox catalysis has appeared as a new paradigm for forging a wide range of chemical bonds under mild conditions using abundant reagents. This approach allows many organic transformations through the generation of various radical species, enabling the valorization of non-traditional partners. A continuing interest has been devoted to the discovery of novel radical-generating procedures. Over the last ten years, strategies using rare-earth complexes as either redox-active centers or as redox-neutral Lewis acids have emerged. This review provides an overview of the recent accomplishments made in this field. It especially aims to demonstrate the utility of rare-earth complexes for ensuring photocatalytic transformations and to inspire future developments.

Molybdenum Nutriture in Humans

2011 ◽  
Vol 16 (3) ◽  
pp. 164-168 ◽  
Author(s):  
Janet A. Novotny
Keyword(s):  
Trace Element ◽  
Xanthine Oxidase ◽  
Aldehyde Oxidase ◽  
Sulfite Oxidase ◽  
Molybdenum Cofactor ◽  
Organic Component ◽  
Trace Mineral ◽  
Wide Range

Molybdenum is a trace element that functions as a cofactor for at least 4 enzymes: sulfite oxidase, xanthine oxidase, aldehyde oxidase, and mitochondrial amidoxime reducing component. In each case, molybdenum is bound to a complex, multiring organic component called molybdopterin, forming the entity molybdenum cofactor. The best sources of dietary molybdenum are legumes, grains, and nuts. Bioavailability of molybdenum is fairly high but depends on form, with molybdenum preparations having greater bioavailability than food-bound molybdenum. Molybdenum deficiency and toxicity are rare, possibly because of the body’s ability to adapt to a wide range of molybdenum intake levels. At low intakes of molybdenum, the fractional transfer of molybdenum from plasma to urine is lower and a greater fraction is deposited into tissues, and at high intakes of molybdenum, the opposite occurs. Molybdenum has proven to be an interesting trace mineral that is essential for life.

scholarly journals Biochemical Characterization of Molybdenum Cofactor-free Nitrate Reductase from Neurospora crassa

2013 ◽  
Vol 288 (20) ◽  
pp. 14657-14671 ◽  
Author(s):  
Phillip Ringel ◽  
Joern Krausze ◽  
Joop van den Heuvel ◽  
Ute Curth ◽  
Antonio J. Pierik ◽  
...  
Keyword(s):  
Nitrate Reductase ◽  
Neurospora Crassa ◽  
Biochemical Characterization ◽  
Nitrate Assimilation ◽  
Molybdenum Cofactor ◽  
Site Formation ◽  
Epr Spectrum ◽  
Redox Active

Nitrate reductase (NR) is a complex molybdenum cofactor (Moco)-dependent homodimeric metalloenzyme that is vitally important for autotrophic organism as it catalyzes the first and rate-limiting step of nitrate assimilation. Beside Moco, eukaryotic NR also binds FAD and heme as additional redox active cofactors, and these are involved in electron transfer from NAD(P)H to the enzyme molybdenum center where reduction of nitrate to nitrite takes place. We report the first biochemical characterization of a Moco-free eukaryotic NR from the fungus Neurospora crassa, documenting that Moco is necessary and sufficient to induce dimer formation. The molybdenum center of NR reconstituted in vitro from apo-NR and Moco showed an EPR spectrum identical to holo-NR. Analysis of mutants unable to bind heme or FAD revealed that insertion of Moco into NR occurs independent from the insertion of any other NR redox cofactor. Furthermore, we showed that at least in vitro the active site formation of NR is an autonomous process.

Dimerization of the plant molybdenum insertase Cnx1E is required for synthesis of the molybdenum cofactor

2016 ◽  
Vol 474 (1) ◽  
pp. 163-178 ◽  
Author(s):  
Joern Krausze ◽  
Corinna Probst ◽  
Ute Curth ◽  
Joachim Reichelt ◽  
Sayantan Saha ◽  
...  
Keyword(s):  
Amino Acid ◽  
Biochemical Characterization ◽  
Molybdenum Cofactor ◽  
Transfer Reactions ◽  
Single Amino Acid ◽  
Amino Acid Exchange ◽  
Prosthetic Group ◽  
Redox Active ◽  
Acid Exchange

The molybdenum cofactor (Moco) is a redox active prosthetic group, essentially required for numerous enzyme-catalyzed two electron transfer reactions. Moco is synthesized by an evolutionarily old and highly conserved multistep pathway. In the last step of Moco biosynthesis, the molybdenum center is inserted into the final Moco precursor adenylated molybdopterin (MPT-AMP). This unique and yet poorly characterized maturation reaction finally yields physiologically active Moco. In the model plant Arabidopsis, the two domain enzyme, Cnx1, is required for Moco formation. Recently, a genetic screen identified novel Arabidopsis cnx1 mutant plant lines each harboring a single amino acid exchange in the N-terminal Cnx1E domain. Biochemical characterization of the respective recombinant Cnx1E variants revealed two different amino acid exchanges (S197F and G175D) that impair Cnx1E dimerization, thus linking Cnx1E oligomerization to Cnx1 functionality. Analysis of the Cnx1E structure identified Cnx1E active site-bound molybdate and magnesium ions, which allowed to fine-map the Cnx1E MPT-AMP-binding site.

General Cyclopropane Assembly via Enantioselective Redox-Active Carbene Transfer to Aliphatic Olefins

2018 ◽  
Author(s):  
Marc Montesinos-Magraner ◽  
Matteo Costantini ◽  
Rodrigo Ramirez-Contreras ◽  
Michael E. Muratore ◽  
Magnus J. Johansson ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Asymmetric Synthesis ◽  
Chemical Space ◽  
Synthetic Approach ◽  
Asymmetric Cyclopropanation ◽  
Redox Active ◽  
Wide Range ◽  
Leaving Group ◽  
Stereoelectronic Properties ◽  
Carbene Transfer

Asymmetric cyclopropane synthesis currently requires bespoke strategies, methods, substrates and reagents, even when targeting similar compounds. This limits the speed and chemical space available for discovery campaigns. Here we introduce a practical and versatile diazocompound, and we demonstrate its performance in the first unified asymmetric synthesis of functionalized cyclopropanes. We found that the redox-active leaving group in this reagent enhances the reactivity and selectivity of geminal carbene transfer. This effect enabled the asymmetric cyclopropanation of a wide range of olefins including unactivated aliphatic alkenes, enabling the 3-step total synthesis of (–)-dictyopterene A. This unified synthetic approach delivers high enantioselectivities that are independent of the stereoelectronic properties of the functional groups transferred. Our results demonstrate that orthogonally-differentiated diazocompounds are viable and advantageous equivalents of single-carbon chirons<i>.</i>

From secretion in Pichia pastoris to application in apple juice processing: Exo-polygalacturonase from Sporothrix schenckii 1099-18

2021 ◽  
Vol 28 ◽  
Author(s):  
Ersin Karataş ◽  
Ahmet Tülek ◽  
Mehmet Mervan Çakar ◽  
Faruk Tamtürk ◽  
Fatih Aktaş ◽  
...  
Keyword(s):  
Pichia Pastoris ◽  
Apple Juice ◽  
Biochemical Characterization ◽  
Signal Sequence ◽  
Sporothrix Schenckii ◽  
Juice Clarification ◽  
Pectinolytic Enzyme ◽  
Pectinolytic Enzymes ◽  
Protein Expression And Purification ◽  
Wide Range

Background: Polygalacturonases are a group of enzymes under pectinolytic enzymes related to enzymes that hydrolyse pectic substances. Polygalacturonases have been used in various industrial applications such as fruit juice clarification, retting of plant fibers, wastewater treatment drinks fermentation, and oil extraction. Objectives: The study was evaluated at the heterologous expression, purification, biochemical characterization, computational modeling, and performance in apple juice clarification of a new exo-polygalacturonase from Sporothrix schenckii 1099-18 (SsExo-PG) in Pichia pastoris. Methods: Recombinant DNA technology was used in this study. Two different pPIC9K plasmids were constructed with native signal sequence-ssexo-pg and alpha signal sequence-ssexo-pg separately. Protein expression and purification performed after plasmids transformed into the Pichia pastoris. Biochemical and structural analyses were performed by using pure SsExo-PG. Results: The purification of SsExo-PG was achieved using a Ni-NTA chromatography system. The enzyme was found to have a molecular mass of approximately 52 kDa. SsExo-PG presented as stable at a wide range of temperature and pH values, and to be more storage stable than other commercial pectinolytic enzyme mixtures. Structural analysis revealed that the catalytic residues of SsExo-PG are somewhat similar to other Exo-PGs. The KM and kcat values for the degradation of polygalacturonic acid (PGA) by the purified enzyme were found to be 0.5868 µM and 179 s-1, respectively. Cu2+ was found to enhance SsExo-PG activity while Ag2+ and Fe2+ almost completely inhibited enzyme activity. The enzyme reduced turbidity up to 80% thus enhanced the clarification of apple juice. SsExo-PG showed promising performance when compared with other commercial pectinolytic enzyme mixtures. Conclusion: The clarification potential of SsExo-PG was revealed by comparing it with commercial pectinolytic enzymes. The following parameters of the process of apple juice clarification processes showed that SsExo-PG is highly stable and has a novel performance.

scholarly journals Spatial Organization of the Redox Active Centers in the Bovine Heart Ubiquinol-cytochrome c Oxidoreductase

1989 ◽  
Vol 264 (2) ◽  
pp. 735-744
Author(s):  
T Ohnishi ◽  
H Schägger ◽  
S W Meinhardt ◽  
R LoBrutto ◽  
T A Link ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Spatial Organization ◽  
Active Centers ◽  
Bovine Heart ◽  
Redox Active

Dendritic Metalloporphyrin-Fullerene Conjugates: Changing the Microenvironment around Redox-Active Centers and its Impact on Charge-Transfer Reactions

2012 ◽  
Vol 18 (33) ◽  
pp. 10427-10435 ◽  
Author(s):  
Evangelos Krokos ◽  
Fabian Spänig ◽  
Michaela Ruppert ◽  
Andreas Hirsch ◽  
Dirk M. Guldi
Keyword(s):  
Charge Transfer ◽  
Transfer Reactions ◽  
Active Centers ◽  
Redox Active ◽  
Charge Transfer Reactions

scholarly journals Non-Stoichiometric Redox Active Perovskite Materials for Solar Thermochemical Fuel Production: A Review

Catalysts ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 611 ◽  
Author(s):  
Anita Haeussler ◽  
Stéphane Abanades ◽  
Julien Jouannaux ◽  
Anne Julbe
Keyword(s):  
Carbon Dioxide ◽  
Solar Energy ◽  
Energy Conversion ◽  
Operating Conditions ◽  
Solar Fuel ◽  
Fuel Production ◽  
Concentrated Solar Energy ◽  
Redox Active ◽  
Conversion Rates ◽  
Wide Range

Due to the requirement to develop carbon-free energy, solar energy conversion into chemical energy carriers is a promising solution. Thermochemical fuel production cycles are particularly interesting because they can convert carbon dioxide or water into CO or H2 with concentrated solar energy as a high-temperature process heat source. This process further valorizes and upgrades carbon dioxide into valuable and storable fuels. Development of redox active catalysts is the key challenge for the success of thermochemical cycles for solar-driven H2O and CO2 splitting. Ultimately, the achievement of economically viable solar fuel production relies on increasing the attainable solar-to-fuel energy conversion efficiency. This necessitates the discovery of novel redox-active and thermally-stable materials able to split H2O and CO2 with both high-fuel productivities and chemical conversion rates. Perovskites have recently emerged as promising reactive materials for this application as they feature high non-stoichiometric oxygen exchange capacities and diffusion rates while maintaining their crystallographic structure during cycling over a wide range of operating conditions and reduction extents. This paper provides an overview of the best performing perovskite formulations considered in recent studies, with special focus on their non-stoichiometry extent, their ability to produce solar fuel with high yield and performance stability, and the different methods developed to study the reaction kinetics.

scholarly journals Evaluation of antimycobacterial rhamnolipid production from non-cytotoxic strains of Pseudomonas aeruginosa isolated from rhizospheric soil of medicinal plants

2016 ◽  
Vol 4 (2) ◽  
pp. 112 ◽  
Author(s):  
Alok K Mishra ◽  
Rikesh K Dubey ◽  
Shivraj M Yabaji ◽  
Swati Jaiswal
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Medicinal Plants ◽  
Biochemical Characterization ◽  
Rhizospheric Soil ◽  
Rhamnolipid Production ◽  
Medicinal Value ◽  
Wide Range ◽  
Rrna Sequencing ◽  
Inhibitory Potential ◽  
Potent Inhibitory Activity

Rhamnolipids (RLs) are the bacterial derived biosurfactants and known for a wide range of industrial and therapeutic applications. They exhibit potent anti-bacterial activity against various gram positive, gram negative and acid fast bacteria including Mycobacterium tuberculosis. Since, Pseudomonas is one of the largest known genuses containing a variety of rhamnolipid producing strains. Therefore, in this study, we selectively isolated the Pseudomonas aeruginosa strains from the rhizospheric soil of the Indian plants of medicinal value, e.g. Azadirachta Indica and Ficus spp., and evaluated them for their natural ability to produce antibacterial rhamnolipids. The bacteria were identified on the basis of 16s rRNA sequencing and biochemical characterization. Among 33 of P. aeruginosa isolates from different soil samples, four isolates showed potent inhibitory activity against methicillin resistant Staphylococcus aureus (MRSA) and fast grower mycobacterial spp. The inhibitory potential of the isolates was found to be correlated with their ability to produce RLs in the medium. The industrial viability of the strains was assessed on the basis of cytotoxicity determining alternative allele, exoS/exoU and cell mediated cytotoxicity against murine macrophages J774.1. The newly isolated strains harbor exoS allele and exhibits lower cell mediated cytotoxicity on macrophage cell line as compared to the clinical strains PA-BAA-427 and PA-27853 used as a control in this study.Evaluation of antimycobacterial rhamnolipid production from non-cytotoxic strains of Pseudomonas aeruginosa isolated from rhizospheric soil of medicinal plants

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