scholarly journals Manufacturing of anisotropic particles by site specific oxidation of thiols

2012 ◽  
Vol 22 (16) ◽  
pp. 7681 ◽  
Author(s):  
Kristofer Eriksson ◽  
LarsErik Johansson ◽  
Emmanuelle Göthelid ◽  
Leif Nyholm ◽  
Sven Oscarsson
Keyword(s):  
Anisotropic Particles ◽  
Site Specific ◽  
Specific Oxidation

scholarly journals Oxidative inactivation of plasmin and other serine proteases by copper and ascorbate

Blood ◽  
1993 ◽  
Vol 82 (5) ◽  
pp. 1522-1531 ◽  
Author(s):  
SE Lind ◽  
JR McDonagh ◽  
CJ Smith
Keyword(s):  
Plasminogen Activator ◽  
Active Site ◽  
Serine Proteases ◽  
Plasminogen Activators ◽  
Single Chain ◽  
Site Specific ◽  
Oxidative Inactivation ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator ◽  
Specific Oxidation

Abstract Fibrin thrombi form at sites of injury, where leukocytes release a variety of oxidants. To determine whether oxidants might affect proteins of the fibrinolytic system, we examined the effects of various oxidants on plasmin. Plasmin was not inhibited by micromolar concentrations of hypochlorous acid, chloramine T, or H2O2. Neither Fe nor Cu affected plasmin alone or in the presence of H2O2. However, incubation of plasmin with 5 mumol/L Cu(I or II) in the presence of the reducing agent ascorbic acid resulted in a loss of its hydrolytic activity towards proteins as well as towards small synthetic substrates. The addition of EDTA, but not mannitol, prevented its inactivation. Inactivation was prevented by the addition of catalase and accelerated by hydrogen peroxide. Preincubation of plasmin with the competitive inhibitor alpha-N-acetyl-L-lysine methyl ester prevented inactivation by Cu(II) and ascorbate. These results together suggest site-specific oxidation of plasmin's active site. Treatment of the plasminogen activators tissue plasminogen activator and two-chain urokinase-type plasminogen activator, as well as trypsin, neutrophil elastase, and thrombin with Cu(II) and ascorbate resulted in a loss of their amidolytic and proteolytic activity, indicating the general susceptibility of serine proteases to this type of oxidation. Oxidation of the zymogens Glu-plasminogen and single-chain urokinase-type plasminogen activator by Cu(II) and ascorbate resulted in the failure of these molecules to generate active enzymes when treated with plasminogen activators or plasmin, respectively. The active site His residue may be the target of oxidative inactivation, as evidenced by the partial protection afforded plasmin by the addition of Zn(II), histidine, or the platinum derivative, platinum(II) (2,2′:6′,2″- terpyridine) chloride. Because platelets contain micromolar concentrations of Cu and leukocytes are rich in ascorbate, Cu-dependent site-specific oxidation might play a role in modulating proteolytic events and the life span of thrombi formed at sites of tissue injury.

scholarly journals N-Ammonium Ylide Mediators for Selective Electrochemical C–H Oxidation

2021 ◽  
Author(s):  
Masato Saito ◽  
Yu Kawamata ◽  
Michael Meanwell ◽  
Rafael Navratil ◽  
Debora Chiodi ◽  
...  
Keyword(s):  
Real World ◽  
First Principles ◽  
Late Stage ◽  
Rapid Screening ◽  
Combinatorial Approach ◽  
Site Specific ◽  
Chemical Reagents ◽  
Lead Compounds ◽  
Complex Settings ◽  
Specific Oxidation

<p>The site-specific oxidation of strong C(sp3)-H bonds is of uncontested utility in organic</p><p>synthesis. From simplifying access to metabolites and late-stage diversification of lead compounds</p><p>to truncating retrosynthetic plans, there is a growing need for new reagents and methods for</p><p>achieving such a transformation in both academic and industrial circles. One main drawback of</p><p>current chemical reagents is the lack of diversity with regards to structure and reactivity that</p><p>prevent a combinatorial approach for rapid screening to be employed. In that regard, directed</p><p>evolution still holds the greatest promise for achieving complex C–H oxidations in a variety of</p><p>complex settings. Herein we present a rationally designed platform that provides a step towards</p><p>this challenge using N-ammonium ylides as electrochemically driven oxidants for site-specific,</p><p>chemoselective C(sp3)–H oxidation. By taking a first-principles approach guided by computation,</p><p>these new mediators were identified and rapidly expanded into a library using ubiquitous building</p><p>blocks and trivial synthesis techniques. The ylide-based approach to C–H oxidation exhibits</p><p>tunable selectivity that is often exclusive to this class of oxidants and can be applied to real world</p><p>problems in the agricultural and pharmaceutical sectors.</p>

Site‐Specific Oxidation‐Induced Stiffening and Shape Morphing of Soft Tough Hydrogels

2018 ◽  
Vol 304 (3) ◽  
pp. 1800589 ◽  
Author(s):  
Jiahui Wang ◽  
Tianzhen Li ◽  
Fan Chen ◽  
Dan Zhou ◽  
Tiansheng Gan ◽  
...  
Keyword(s):  
Site Specific ◽  
Shape Morphing ◽  
Specific Oxidation

Element- and site-specific oxidation state and cation distribution in manganese ferrite films by diffraction anomalous fine structure

2008 ◽  
Vol 93 (5) ◽  
pp. 052504 ◽  
Author(s):  
Aria Yang ◽  
Zhaohui Chen ◽  
Anton L. Geiler ◽  
Xu Zuo ◽  
Daniel Haskel ◽  
...  
Keyword(s):  
Fine Structure ◽  
Oxidation State ◽  
Cation Distribution ◽  
Manganese Ferrite ◽  
Site Specific ◽  
Ferrite Films ◽  
Specific Oxidation

Site specific oxidation of amino acid residues in rat lens γ-crystallin induced by low-dose γ-irradiation

2015 ◽  
Vol 466 (4) ◽  
pp. 622-628 ◽  
Author(s):  
Ingu Kim ◽  
Takeshi Saito ◽  
Norihiko Fujii ◽  
Takashi Kanamoto ◽  
Toshiyuki Chatake ◽  
...  
Keyword(s):  
Amino Acid ◽  
Low Dose ◽  
Amino Acid Residues ◽  
Γ Irradiation ◽  
Site Specific ◽  
Specific Oxidation
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