scholarly journals Chemical Reactivities of ortho-Quinones Produced in Living Organisms: Fate of Quinonoid Products Formed by Tyrosinase and Phenoloxidase Action on Phenols and Catechols

2020 ◽  
Vol 21 (17) ◽  
pp. 6080 ◽  
Author(s):  
Shosuke Ito ◽  
Manickam Sugumaran ◽  
Kazumasa Wakamatsu
Keyword(s):  
Nucleophilic Addition ◽  
Quinone Methide ◽  
Side Chain ◽  
Amino Groups ◽  
Melanin Biosynthesis ◽  
Fast Reactions ◽  
Carcinogenic Effects ◽  
Oxidation Of Phenols ◽  
Living Organisms ◽  
Cellular Components

Tyrosinase catalyzes the oxidation of phenols and catechols (o-diphenols) to o-quinones. The reactivities of o-quinones thus generated are responsible for oxidative browning of plant products, sclerotization of insect cuticle, defense reaction in arthropods, tunichrome biochemistry in tunicates, production of mussel glue, and most importantly melanin biosynthesis in all organisms. These reactions also form a set of major reactions that are of nonenzymatic origin in nature. In this review, we summarized the chemical fates of o-quinones. Many of the reactions of o-quinones proceed extremely fast with a half-life of less than a second. As a result, the corresponding quinone production can only be detected through rapid scanning spectrophotometry. Michael-1,6-addition with thiols, intramolecular cyclization reaction with side chain amino groups, and the redox regeneration to original catechol represent some of the fast reactions exhibited by o-quinones, while, nucleophilic addition of carboxyl group, alcoholic group, and water are mostly slow reactions. A variety of catecholamines also exhibit side chain desaturation through tautomeric quinone methide formation. Therefore, quinone methide tautomers also play a pivotal role in the fate of numerous o-quinones. Armed with such wide and dangerous reactivity, o-quinones are capable of modifying the structure of important cellular components especially proteins and DNA and causing severe cytotoxicity and carcinogenic effects. The reactivities of different o-quinones involved in these processes along with special emphasis on mechanism of melanogenesis are discussed.

Enhanced stability and gene silencing ability of siRNA-loaded polyion complexes formulated from polyaspartamide derivatives with a repetitive array of amino groups in the side chain

Biomaterials ◽  
2012 ◽  
Vol 33 (9) ◽  
pp. 2770-2779 ◽  
Author(s):  
Tomoya Suma ◽  
Kanjiro Miyata ◽  
Takehiko Ishii ◽  
Satoshi Uchida ◽  
Hirokuni Uchida ◽  
...  
Keyword(s):  
Gene Silencing ◽  
Side Chain ◽  
Amino Groups ◽  
Enhanced Stability ◽  
Polyion Complexes

scholarly journals Gas Phase Computational Study of Diclofenac Adsorption on Chitosan Materials

Molecules ◽  
2020 ◽  
Vol 25 (11) ◽  
pp. 2549
Author(s):  
Anna Kaczmarek-Kędziera
Keyword(s):  
Interaction Energy ◽  
Gas Phase ◽  
Computational Study ◽  
Intramolecular Interactions ◽  
Amino Groups ◽  
Inflammatory Drugs ◽  
Low Costs ◽  
Anti Inflammatory ◽  
Single Polymer Chain ◽  
Living Organisms

Environmental pollution with non-steroidal anti-inflammatory drugs and their metabolites exposes living organisms on their long-lasting, damaging influence. Hence, the ways of non-steroidal anti-inflammatory drugs (NSAIDs) removal from soils and wastewater is sought for. Among the potential adsorbents, biopolymers are employed for their good availability, biodegradability and low costs. The first available theoretical modeling study of the interactions of diclofenac with models of pristine chitosan and its modified chains is presented here. Supermolecular interaction energy in chitosan:drug complexes is compared with the the mutual attraction of the chitosan dimers. Supermolecular interaction energy for the chitosan-diclofenac complexes is significantly lower than the mutual interaction between two chitosan chains, suggesting that the diclofenac molecule will encounter problems when penetrating into the chitosan material. However, its surface adsorption is feasible due to a large number of hydrogen bond donors and acceptors both in biopolymer and in diclofenac. Modification of chitosan material introducing long-distanced amino groups significantly influences the intramolecular interactions within a single polymer chain, thus blocking the access of diclofenac to the biopolymer backbone. The strongest attraction between two chitosan chains with two long-distanced amino groups can exceed 120 kcal/mol, while the modified chitosan:diclofenac interaction remains of the order of 20 to 40 kcal/mol.

scholarly journals The effect of polyamines on the poly(adenylic acid)-induced inhibition of ribonuclease activity

1981 ◽  
Vol 193 (1) ◽  
pp. 325-337 ◽  
Author(s):  
T P Karpetsky ◽  
K K Shriver ◽  
C C Levy
Keyword(s):  
Human Plasma ◽  
Segment Length ◽  
Side Chain ◽  
Amino Groups ◽  
Human Spleen ◽  
Low Concentrations ◽  
Degradation Rates ◽  
Adenylic Acid ◽  
Bovine Pancreas ◽  
Terminal Poly

Segments of poly(A) at the 3′-termini of 5 S rRNA inhibit the activities of ribonucleases from Citrobacter, Enterobacter, bovine pancreas, human spleen and human plasma. Certain polyamines, or compounds containing polyamine substructures, mediate reversal of this inhibition. Effective compounds contain three amino groups, at least two of which are charged and are separated from the others by no less than three carbon atoms. Spermidine and 9-aminoacridines, which contain substituted propyl- or butylamino moieties at the 9-amino position and which bear two positive charges per molecule, are efficacious at low concentrations (5 microM). A decrease in effectiveness is associated with the removal of one aromatic ring from the 9-aminoacridines. However, the resulting 4-aminoquinolines, unlike the acridines, do not inhibit enzyme activity when present in concentrations above 30 microM. Relocating the diamino side chain from the 4- to the 8-position of the quinoline nucleus causes a decrease in charge density to +1, with the result that such compounds are ineffective. The orders of polyamine efficacy of reversal of inhibition were similar for enzymes from Citrobacter, bovine pancreas, and human plasma, and paralleled the order of binding of polyamines to either poly(A) or 5 S rRNA. This was not the case with Enterobacter and human spleen RNAases, indicating that the identity of the most effective polyamines depends on the RNAase studied. The combination of variable 3′-terminal poly(A) segment length and polyamine identity and concentration constitutes a system by which RNAase activities, and, therefore, substrate-degradation rates, may be easily varied.

scholarly journals Incorporation of 3-Aminobenzanthrone into 2′-Deoxyoligonucleotides and Its Impact on Duplex Stability

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Mark Lukin ◽  
Tanya Zaliznyak ◽  
Francis Johnson ◽  
Carlos R. de los Santos
Keyword(s):  
Dna Adducts ◽  
Nmr Spectra ◽  
Room Temperature ◽  
Helical Structure ◽  
Environmental Pollutant ◽  
Synthetic Approach ◽  
Amino Groups ◽  
Double Helical Structure ◽  
Duplex Stability ◽  
Living Organisms

3-Nitrobenzanthrone (3NBA), an environmental pollutant and potent mutagen, causes DNA damage via the reaction of its metabolically activated form with the exocyclic amino groups of purines and the C-8 position of guanine. The present work describes a synthetic approach to the preparation of oligomeric 2′-deoxyribonucleotides containing a 2-(2′-deoxyguanosin-N2-yl)-3-aminobenzanthrone moiety, one of the major DNA adducts found in tissues of living organisms exposed to 3NBA. The NMR spectra indicate that the damaged oligodeoxyribonucleotide is capable of forming a regular double helical structure with the polyaromatic moiety assuming a single conformation at room temperature; the spectra suggest that the 3ABA moiety resides in the duplex minor groove pointing toward the 5′-end of the modified strand. Thermodynamic studies show that the dG(N2)-3ABA lesion has a stabilizing effect on the damaged duplex, a fact that correlates well with the long persistence of this damage in living organisms.

scholarly journals Shedding light on biology of bacterial cells

2016 ◽  
Vol 371 (1707) ◽  
pp. 20150499 ◽  
Author(s):  
Johannes P. Schneider ◽  
Marek Basler
Keyword(s):  
Light Microscopy ◽  
Live Cell Imaging ◽  
Spatial Organization ◽  
Cell Imaging ◽  
Live Cell ◽  
Bacterial Cells ◽  
Resolution Limit ◽  
Detection Techniques ◽  
Living Organisms ◽  
Cellular Components

To understand basic principles of living organisms one has to know many different properties of all cellular components, their mutual interactions but also their amounts and spatial organization. Live-cell imaging is one possible approach to obtain such data. To get multiple snapshots of a cellular process, the imaging approach has to be gentle enough to not disrupt basic functions of the cell but also have high temporal and spatial resolution to detect and describe the changes. Light microscopy has become a method of choice and since its early development over 300 years ago revolutionized our understanding of living organisms. As most cellular components are indistinguishable from the rest of the cellular contents, the second revolution came from a discovery of specific labelling techniques, such as fusions to fluorescent proteins that allowed specific tracking of a component of interest. Currently, several different tags can be tracked independently and this allows us to simultaneously monitor the dynamics of several cellular components and from the correlation of their dynamics to infer their respective functions. It is, therefore, not surprising that live-cell fluorescence microscopy significantly advanced our understanding of basic cellular processes. Current cameras are fast enough to detect changes with millisecond time resolution and are sensitive enough to detect even a few photons per pixel. Together with constant improvement of properties of fluorescent tags, it is now possible to track single molecules in living cells over an extended period of time with a great temporal resolution. The parallel development of new illumination and detection techniques allowed breaking the diffraction barrier and thus further pushed the resolution limit of light microscopy. In this review, we would like to cover recent advances in live-cell imaging technology relevant to bacterial cells and provide a few examples of research that has been possible due to imaging. This article is part of the themed issue ‘The new bacteriology’.

Towards an Exergy Analysis of Diffusive and Non-Diffusive Processes in Living Organisms

2016 ◽  
Vol 7 ◽  
pp. 177-184
Author(s):  
Antonio F. Miguel
Keyword(s):  
Exergy Analysis ◽  
Balance Equations ◽  
Physiological Processes ◽  
Performance Of Systems ◽  
Laws Of Thermodynamics ◽  
Living Organisms ◽  
Diffusive Processes ◽  
Cellular Components ◽  
Exergy Balance ◽  
Insight Into

Living organisms are open dissipative thermodynamic systems that rely on mechano-thermo-electrochemical interactions to survive. Plant physiological processes allow plants to survive by converting solar radiation into chemical energy, and store that energy in form that can be used. Mammals catabolize food to obtain energy that is used to fuel, build and repair the cellular components. The exergy balance is a combined statement of the first and second laws of thermodynamics. It provides insight into the performance of systems. In this paper, exergy balance equations for both mammal’s and green plants are presented and analyzed.

Dynamics of Lysine Side-Chain Amino Groups in a Protein Studied by Heteronuclear1H−15N NMR Spectroscopy

2011 ◽  
Vol 133 (4) ◽  
pp. 909-919 ◽  
Author(s):  
Alexandre Esadze ◽  
Da-Wei Li ◽  
Tianzhi Wang ◽  
Rafael Brüschweiler ◽  
Junji Iwahara
Keyword(s):  
Nmr Spectroscopy ◽  
Side Chain ◽  
15N Nmr ◽  
Amino Groups ◽  
Lysine Side Chain ◽  
15N Nmr Spectroscopy
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