scholarly journals (Hydr)oxo-bridged heme complexes: From structure to reactivity

2019 ◽  
Vol 23 (11n12) ◽  
pp. 1286-1307
Author(s):  
Maria C. Carrasco ◽  
Shabnam Hematian
Keyword(s):  
Functional Materials ◽  
Structural Features ◽  
Nitric Oxide Reductase ◽  
Iron Porphyrins ◽  
Heme Enzymes ◽  
Coordination Environment ◽  
Wide Range ◽  
Comprehensive Picture ◽  
Range Of Functions ◽  
Copper Oxidase

Iron–porphyrins ([Formula: see text] hemes) are present throughout the biosphere and perform a wide range of functions, particularly those that involve complex multiple-electron redox processes. Some common heme enzymes involved in these processes include cytochrome P450, heme/copper oxidase or heme/non-heme diiron nitric oxide reductase. Consequently, the (hydr)oxo-bridged heme species have been studied for the important roles that they play in many life processes or for their application for catalysis and preparation of new functional materials. This review encompasses important synthetic, structural and reactivity aspects of the (hydr)oxo-bridged heme constructs that govern their function and application. The properties and reactivity of the bridging (hydr)oxo moieties are directly dictated by the coordination environment of the heme core, the nature and ligation of the second metal center attached to the (hydr)oxo group, the presence or absence of a linker, and the degree of flexibility around that linker within the scaffold. Here, we summarize the structural features of all known (hydr)oxo-bridged heme constructs and use those to categorize and thus, provide a more comprehensive picture of structure–function relationships.

scholarly journals Novel Interactions of Adrenodoxin-Related [2Fe-2S] Plant Ferredoxins MFDX1 and MFDX2 Indicate Their Involvement in a Wide Spectrum of Functions in Plant Mitochondria

2019 ◽  
Vol 73 (6) ◽  
pp. 478-486
Author(s):  
Elena K. Shematorova ◽  
Ivan Yu. Slovokhotov ◽  
Vladimir N. Shmakov ◽  
Marat R. Khaliluev ◽  
Dmitry G. Shpakovski ◽  
...  
Keyword(s):  
Protein Complexes ◽  
Wide Spectrum ◽  
Plant Mitochondria ◽  
Mitochondrial Protein ◽  
Regulatory System ◽  
Structural Features ◽  
Cytochrome P450scc ◽  
Digitalis Purpurea ◽  
Wide Range ◽  
Range Of Functions

Abstract Electron transfer chains of plant organelles (both chloroplasts and mitochondria) contain their own special set of ferredoxins. The relatively recently described adrenodoxin-like [2Fe-2S]-ferredoxins MFDX1 and MFDX2 of plant mitochondria are among the least studied of these. Until now, the only established function for them is participation in the final stage of biotin biosynthesis. In this work, using genetic and biochemical approaches, we searched for possible partners of these proteins in the genomes and proteomes of tobacco (Nicotiana tabacum L.) and foxglove (Digitalis purpurea L.) plants. MORF9 protein, one of the auxiliary components of the RNA editing complex of organelles (editosome), was found among the most prominent protein partners of adrenodoxin-like [2Fe-2S] tobacco ferredoxins. According to the results obtained from the yeast two-hybrid system, NtMFDX1 and NtMFDX2 of tobacco also bind and interact productively with the previously uncharacterised long non-coding polyadenylated RNA, which, based on its structural features, is capable of regulating the function of a number of components of complexes I (Nad1, Nad5) and III (protein of the cytochrome c synthesis system CcmF) and contributes to the formation of Fe/S-clusters in the corresponding protein complexes of the respiratory chain of plant mitochondria. We found one of the main components of the thiazol synthase complex (mitochondrial protein DpTHI1) to be the partner of ferredoxin DpMFDX2 of Digitalis purpurea. Finally, additional arguments were obtained in favour of the possible participation of MFDX1 and MFDX2 in the very ancient, but only recently described ‘progesterone’ steroid hormonal regulatory system: in leaves of the previously constructed CYP11A1-transgenic tomato plants, only the mature form of mitochondrial cytochrome P450scc (CYP11A1) of mammals is able to enter the mitochondria, where the above-mentioned components of the electron transport chain are localised. In summary, all of the newly revealed interactions of adrenodoxin-like [2Fe-2S] ferredoxins MFDX1 and MFDX2 indicate their participation in a wide range of functions in plant mitochondria.

pH-Dependent Thermal Stability of Vibrio cholerae L-asparaginase

2019 ◽  
Vol 26 (10) ◽  
pp. 743-750 ◽  
Author(s):  
Remya Radha ◽  
Sathyanarayana N. Gummadi
Keyword(s):  
Vibrio Cholerae ◽  
Conformational Changes ◽  
Kinetic Studies ◽  
Structural Features ◽  
Structure Stability ◽  
Kcal Mole ◽  
Scanning Calorimetry ◽  
Wide Range ◽  
Ph Dependent ◽  
Ph Range

Background:pH is one of the decisive macromolecular properties of proteins that significantly affects enzyme structure, stability and reaction rate. Change in pH may protonate or deprotonate the side group of aminoacid residues in the protein, thereby resulting in changes in chemical and structural features. Hence studies on the kinetics of enzyme deactivation by pH are important for assessing the bio-functionality of industrial enzymes. L-asparaginase is one such important enzyme that has potent applications in cancer therapy and food industry.Objective:The objective of the study is to understand and analyze the influence of pH on deactivation and stability of Vibrio cholerae L-asparaginase.Methods:Kinetic studies were conducted to analyze the effect of pH on stability and deactivation of Vibrio cholerae L-asparaginase. Circular Dichroism (CD) and Differential Scanning Calorimetry (DSC) studies have been carried out to understand the pH-dependent conformational changes in the secondary structure of V. cholerae L-asparaginase.Results:The enzyme was found to be least stable at extreme acidic conditions (pH< 4.5) and exhibited a gradual increase in melting temperature from 40 to 81 °C within pH range of 4.0 to 7.0. Thermodynamic properties of protein were estimated and at pH 7.0 the protein exhibited ΔG37of 26.31 kcal mole-1, ΔH of 204.27 kcal mole-1 and ΔS of 574.06 cal mole-1 K-1.Conclusion:The stability and thermodynamic analysis revealed that V. cholerae L-asparaginase was highly stable over a wide range of pH, with the highest stability in the pH range of 5.0–7.0.

Structure, Function and Interactions of Tau: Particular Focus on Potential Drug Targets for the Treatment of Tauopathies

2018 ◽  
Vol 17 (5) ◽  
pp. 325-337 ◽  
Author(s):  
Hojjat Borna ◽  
Kasim Assadoulahei ◽  
Gholamhossein Riazi ◽  
Asghar Beigi Harchegani ◽  
Alireza Shahriary
Keyword(s):  
Tau Protein ◽  
Drug Targets ◽  
Brain Injuries ◽  
Potential Drug ◽  
Microtubule Network ◽  
Wide Range ◽  
Potential Risk Factors ◽  
Range Of Functions ◽  
Potential Drug Targets

Background & Objective: Neurodegenrative diseases are among the most widespread lifethreatening disorders around the world in elderly ages. The common feature of a group of neurodegenerative disorders, called tauopathies, is an accumulation of microtubule associated protein tau inside the neurons. The exact mechanism underlying tauopathies is not well-understood but several factors such as traumatic brain injuries and genetics are considered as potential risk factors. Although tau protein is well-known for its key role in stabilizing and organization of axonal microtubule network, it bears a broad range of functions including DNA protection and participation in signaling pathways. Moreover, the flexible unfolded structure of tau facilitates modification of tau by a wide range of intracellular enzymes which in turn broadens tau function and interaction spectrum. The distinctive properties of tau protein concomitant with the crucial role of tau interaction partners in the progression of neurodegeneration suggest tau and its binding partners as potential drug targets for the treatment of neurodegenerative diseases. Conclusion: This review aims to give a detailed description of structure, functions and interactions of tau protein in order to provide insight into potential therapeutic targets for treatment of tauopathies.

Application of Nitrogen Heterocyclic Carbenes in Organocatalysis

2020 ◽  
Vol 09 ◽  
Author(s):  
Minita Ojha ◽  
R. K. Bansal
Keyword(s):  
Asymmetric Catalysis ◽  
Building Blocks ◽  
Structural Features ◽  
Heterocyclic Carbenes ◽  
Stetter Reaction ◽  
Metal Pollutants ◽  
Synthetic Strategy ◽  
Wide Range ◽  
Benzoin Condensation ◽  
Nitrogen Heterocyclic

Background: During the last two decades, horizon of research in the field of Nitrogen Heterocyclic Carbenes (NHC) has widened remarkably. NHCs have emerged as ubiquitous species having applications in a broad range of fields, including organocatalysis and organometallic chemistry. The NHC-induced non-asymmetric catalysis has turned out to be a really fruitful area of research in recent years. Methods: By manipulating structural features and selecting appropriate substituent groups, it has been possible to control the kinetic and thermodynamic stability of a wide range of NHCs, which can be tolerant to a variety of functional groups and can be used under mild conditions. NHCs are produced by different methods, such as deprotonation of Nalkylhetrocyclic salt, transmetallation, decarboxylation and electrochemical reduction. Results: The NHCs have been used successfully as catalysts for a wide range of reactions making a large number of building blocks and other useful compounds accessible. Some of these reactions are: benzoin condensation, Stetter reaction, Michael reaction, esterification, activation of esters, activation of isocyanides, polymerization, different cycloaddition reactions, isomerization, etc. The present review includes all these examples published during the last 10 years, i.e. from 2010 till date. Conclusion: The NHCs have emerged as versatile and powerful organocatalysts in synthetic organic chemistry. They provide the synthetic strategy which does not burden the environment with metal pollutants and thus fit in the Green Chemistry.

Career Development Theory: An Integrated Analysis

2020 ◽  
Author(s):  
Julia Yates
Keyword(s):  
Career Choice ◽  
Subject Matter ◽  
Academic Disciplines ◽  
Development Theory ◽  
Integrated Analysis ◽  
Theoretical Frameworks ◽  
Wide Range ◽  
Comprehensive Picture ◽  
The Subject ◽  
Career Practice

Career theories are developed to help make sense of the complexity of career choice and development. The intricacy of the subject matter is such that career theories most often focus on one or two aspects of the phenomenon. As such, the challenges of integrating the theories with each other, and integrating them within career practice, are not insignificant. In this chapter, an overview of the theoretical landscape is offered that illustrates how the theories align with each other to build up a comprehensive picture of career choice and development. The chapter introduces a wide range of theoretical frameworks, spanning seven decades and numerous academic disciplines, and discusses the most well-known theorists alongside less familiar names. The chapter is structured around four concepts: identity, environment, career learning, and psychological career resources. Suggestions are offered for the incorporation of theories in career practice.

scholarly journals Characterizing Bacterial Cellulose Produced byKomagataeibacter sucrofermentans H-110 on Molasses Medium and Obtaining a Biocomposite Based on It for the Adsorption of Fluoride

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1422
Author(s):  
Viktor V. Revin ◽  
Alexander V. Dolganov ◽  
Elena V. Liyaskina ◽  
Natalia B. Nazarova ◽  
Anastasia V. Balandina ◽  
...  
Keyword(s):  
Composite Material ◽  
Adsorption Capacity ◽  
Bacterial Cellulose ◽  
Functional Materials ◽  
Degree Of Crystallinity ◽  
Maximum Adsorption Capacity ◽  
Fluoride Ions ◽  
Sorption Ability ◽  
Wide Range ◽  
Biocomposite Material

Currently, there is an increased demand for biodegradable materials in society due to growing environmental problems. Special attention is paid to bacterial cellulose, which, due to its unique properties, has great prospects for obtaining functional materials for a wide range of applications, including adsorbents. In this regard, the aim of this study was to obtain a biocomposite material with adsorption properties in relation to fluoride ions based on bacterial cellulose using a highly productive strain of Komagataeibacter sucrofermentans H-110 on molasses medium. Films of bacterial cellulose were obtained. Their structure and properties were investigated by FTIR spectroscopy, NMR, atomic force microscopy, scanning electron microscopy, and X-ray structural analysis. The results show that the fiber thickness of the bacterial cellulose formed by the K. sucrofermentans H-110 strain on molasses medium was 60–90 nm. The degree of crystallinity of bacterial cellulose formed on the medium was higher than on standard Hestrin and Schramm medium and amounted to 83.02%. A new biocomposite material was obtained based on bacterial cellulose chemically immobilized on its surface using atomic-layer deposition of nanosized aluminum oxide films. The composite material has high sorption ability to remove fluoride ions from an aqueous medium. The maximum adsorption capacity of the composite is 80.1 mg/g (F/composite). The obtained composite material has the highest adsorption capacity of fluoride from water in comparison with other sorbents. The results prove the potential of bacterial cellulose-based biocomposites as highly effective sorbents for fluoride.

scholarly journals Ring-Forming Polymerization toward Perfluorocyclobutyl and Ortho-Diynylarene-Derived Materials: From Synthesis to Practical Applications

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1486
Author(s):  
Eugene B. Caldona ◽  
Ernesto I. Borrego ◽  
Ketki E. Shelar ◽  
Karl M. Mukeba ◽  
Dennis W. Smith
Keyword(s):  
Chemical Resistance ◽  
Structural Features ◽  
Review Article ◽  
Aryl Ether ◽  
Aromatic Rings ◽  
Practical Applications ◽  
Repeat Units ◽  
Wide Range ◽  
Synthetic Routes ◽  
The Cost

Many desirable characteristics of polymers arise from the method of polymerization and structural features of their repeat units, which typically are responsible for the polymer’s performance at the cost of processability. While linear alternatives are popular, polymers composed of cyclic repeat units across their backbones have generally been shown to exhibit higher optical transparency, lower water absorption, and higher glass transition temperatures. These specifically include polymers built with either substituted alicyclic structures or aromatic rings, or both. In this review article, we highlight two useful ring-forming polymer groups, perfluorocyclobutyl (PFCB) aryl ether polymers and ortho-diynylarene- (ODA) based thermosets, both demonstrating outstanding thermal stability, chemical resistance, mechanical integrity, and improved processability. Different synthetic routes (with emphasis on ring-forming polymerization) and properties for these polymers are discussed, followed by their relevant applications in a wide range of aspects.

scholarly journals Role of Physical Exercise and Nutraceuticals in Modulating Molecular Pathways of Osteoarthritis

2021 ◽  
Vol 22 (11) ◽  
pp. 5722
Author(s):  
Alessandro de Sire ◽  
Nicola Marotta ◽  
Cinzia Marinaro ◽  
Claudio Curci ◽  
Marco Invernizzi ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
Synergistic Effects ◽  
Molecular Pathways ◽  
Epigenetic Changes ◽  
Pathological Features ◽  
Oxidative Signaling ◽  
Cartilage Extracellular Matrix ◽  
Wide Range ◽  
Comprehensive Picture

Osteoarthritis (OA) is a painful and disabling disease that affects millions of patients. Its etiology is largely unknown, but it is most likely multifactorial. OA pathogenesis involves the catabolism of the cartilage extracellular matrix and is supported by inflammatory and oxidative signaling pathways and marked epigenetic changes. To delay OA progression, a wide range of exercise programs and naturally derived compounds have been suggested. This literature review aims to analyze the main signaling pathways and the evidence about the synergistic effects of these two interventions to counter OA. The converging nutrigenomic and physiogenomic intervention could slow down and reduce the complex pathological features of OA. This review provides a comprehensive picture of a possible signaling approach for targeting OA molecular pathways, initiation, and progression.

scholarly journals Advanced Functional Materials Based on Nanocellulose for Pharmaceutical/Medical Applications

Pharmaceutics ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1125
Author(s):  
Raluca Nicu ◽  
Florin Ciolacu ◽  
Diana E. Ciolacu
Keyword(s):  
Rapid Development ◽  
Cellulose Nanofibrils ◽  
Functional Materials ◽  
Medical Applications ◽  
Bacterial Nanocellulose ◽  
Green Materials ◽  
Wide Range ◽  
In Vivo Cytotoxicity

Nanocelluloses (NCs), with their remarkable characteristics, have proven to be one of the most promising “green” materials of our times and have received special attention from researchers in nanomaterials. A diversity of new functional materials with a wide range of biomedical applications has been designed based on the most desirable properties of NCs, such as biocompatibility, biodegradability, and their special physicochemical properties. In this context and under the pressure of rapid development of this field, it is imperative to synthesize the successes and the new requirements in a comprehensive review. The first part of this work provides a brief review of the characteristics of the NCs (cellulose nanocrystals—CNC, cellulose nanofibrils—CNF, and bacterial nanocellulose—BNC), as well as of the main functional materials based on NCs (hydrogels, nanogels, and nanocomposites). The second part presents an extensive review of research over the past five years on promising pharmaceutical and medical applications of nanocellulose-based materials, which have been discussed in three important areas: drug-delivery systems, materials for wound-healing applications, as well as tissue engineering. Finally, an in-depth assessment of the in vitro and in vivo cytotoxicity of NCs-based materials, as well as the challenges related to their biodegradability, is performed.

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