scholarly journals Interaction of Melanin with Metal Ions Modulates Their Cytotoxic Potential

2021 ◽  
Author(s):  
Tadeusz Sarna ◽  
Harold M. Swartz ◽  
Andrzej Zadlo
Keyword(s):  
Metal Ions ◽  
Biological Function ◽  
Melanin Granule ◽  
Redox Activation ◽  
Redox Active ◽  
Active Metal ◽  
Physicochemical Methods ◽  
Catalyzed Reactions ◽  
Enzyme Catalyzed Reactions ◽  
Redox Active Metal

AbstractMelanin is one the most common biological pigments. In humans, specialized cells called melanocytes synthesize the pigment from tyrosine and 3,4-dihydroxyphenylalanine via enzyme-catalyzed reactions and spontaneous processes. The formed melanin granule consists of nanoaggregates of oligomers containing different monomers. Although the main biological function of melanin is protection against damage from solar radiation, melanin may also be involved in protection against oxidative stress. In the latter function, sequestration of redox-active metal ions and scavenging of reactive oxygen species are of importance. The paper reviews basic physicochemical properties of melanin responsible for binding of metal ions and discusses specific conditions that may induce cytotoxicity of metal ions such as iron and copper by facilitating their redox activation and release from melanin. While the value of EPR spectroscopy and other EPR-related techniques for the study of melanin is emphasized, the concomitant use of other physicochemical methods is the most efficient approach.

FerriNaphth: A fluorescent chemodosimeter for redox active metal ions

2010 ◽  
Vol 39 (17) ◽  
pp. 4155 ◽  
Author(s):  
Randy K. Jackson ◽  
Yu Shi ◽  
Xudong Yao ◽  
Shawn C. Burdette
Keyword(s):  
Metal Ions ◽  
Redox Active ◽  
Active Metal ◽  
Fluorescent Chemodosimeter ◽  
Redox Active Metal

scholarly journals Inhibition of Cellulase-Catalyzed Lignocellulosic Hydrolysis by Iron and Oxidative Metal Ions and Complexes

2010 ◽  
Vol 76 (23) ◽  
pp. 7673-7682 ◽  
Author(s):  
Ani Tejirian ◽  
Feng Xu
Keyword(s):  
Metal Ions ◽  
Biomass Conversion ◽  
Oxidation Potential ◽  
General Effect ◽  
Ferric Ions ◽  
Redox Active ◽  
Active Metal ◽  
Catalytic Role ◽  
Lignocellulose Hydrolysis ◽  
Redox Active Metal

ABSTRACT Enzymatic lignocellulose hydrolysis plays a key role in microbially driven carbon cycling and energy conversion and holds promise for bio-based energy and chemical industries. Cellulases (key lignocellulose-active enzymes) are prone to interference from various noncellulosic substances (e.g., metal ions). During natural cellulolysis, these substances may arise from other microbial activities or abiotic events, and during industrial cellulolysis, they may be derived from biomass feedstocks or upstream treatments. Knowledge about cellulolysis-inhibiting reactions is of importance for the microbiology of natural biomass degradation and the development of biomass conversion technology. Different metal ions, including those native to microbial activity or employed for biomass pretreatments, are often tested for enzymatic cellulolysis. Only a few metal ions act as inhibitors of cellulases, which include ferrous and ferric ions as well as cupric ion. In this study, we showed inhibition by ferrous/ferric ions as part of a more general effect from oxidative (or redox-active) metal ions and their complexes. The correlation between inhibition and oxidation potential indicated the oxidative nature of the inhibition, and the dependence on air established the catalytic role that iron ions played in mediating the dioxygen inhibition of cellulolysis. Individual cellulases showed different susceptibilities to inhibition. It is likely that the inhibition exerted its effect more on cellulose than on cellulase. Strong iron ion chelators and polyethylene glycols could mitigate the inhibition. Potential microbiological and industrial implications of the observed effect of redox-active metal ions on enzymatic cellulolysis, as well as the prevention and mitigation of this effect in industrial biomass conversion, are discussed.

Intracellular Redox Active Metal Ions Mediate the Differential Susceptibility of Lung and Brain Cancer Cells to Pharmacological Ascorbate

2014 ◽  
Vol 76 ◽  
pp. S131
Author(s):  
Joshua D Schoenfeld ◽  
Zita A. Sibenaller ◽  
Kranti A. Mapuskar ◽  
Joseph J. Cullen ◽  
Garry R. Buettner ◽  
...  
Keyword(s):  
Metal Ions ◽  
Cancer Cells ◽  
Brain Cancer ◽  
Differential Susceptibility ◽  
Redox Active ◽  
Active Metal ◽  
Redox Active Metal ◽  
Intracellular Redox

scholarly journals Hypothesis: Soluble AβOligomers in Association with Redox-Active Metal Ions Are the Optimal Generators of Reactive Oxygen Species in Alzheimer's Disease

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Brian J. Tabner ◽  
Jennifer Mayes ◽  
David Allsop
Keyword(s):  
Alzheimer’S Disease ◽  
Reactive Oxygen Species ◽  
Alzheimer's Disease ◽  
Hydrogen Peroxide ◽  
Metal Ions ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Redox Active ◽  
Active Metal ◽  
Redox Active Metal

Considerable evidence points to oxidative stress in the brain as an important event in the early stages of Alzheimer's disease (AD). The transition metal ions of Cu, Fe, and Zn are all enriched in the amyloid cores of senile plaques in AD. Those of Cu and Fe are redox active and bind to Aβin vitro. When bound, they can facilitate the reduction of oxygen to hydrogen peroxide, and of the latter to the hydroxyl radical. This radical is very aggressive and can cause considerable oxidative damage. Recent research favours the involvement of small, soluble oligomers as the aggregating species responsible for Aβ neurotoxicity. We propose that the generation of reactive oxygen species (i.e., hydrogen peroxide and hydroxyl radicals) by these oligomers, in association with redox-active metal ions, is a key molecular mechanism underlying the pathogenesis of AD and some other neurodegenerative disorders.

scholarly journals Redox-Active Metal Ions and Amyloid-Degrading Enzymes in Alzheimer’s Disease

2021 ◽  
Vol 22 (14) ◽  
pp. 7697
Author(s):  
Namdoo Kim ◽  
Hyuck Jin Lee
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Metal Ions ◽  
Normal Brain ◽  
Insulin Degrading Enzyme ◽  
Degrading Enzymes ◽  
Redox Active ◽  
Active Metal ◽  
The Brain ◽  
Redox Active Metal

Redox-active metal ions, Cu(I/II) and Fe(II/III), are essential biological molecules for the normal functioning of the brain, including oxidative metabolism, synaptic plasticity, myelination, and generation of neurotransmitters. Dyshomeostasis of these redox-active metal ions in the brain could cause Alzheimer’s disease (AD). Thus, regulating the levels of Cu(I/II) and Fe(II/III) is necessary for normal brain function. To control the amounts of metal ions in the brain and understand the involvement of Cu(I/II) and Fe(II/III) in the pathogenesis of AD, many chemical agents have been developed. In addition, since toxic aggregates of amyloid-β (Aβ) have been proposed as one of the major causes of the disease, the mechanism of clearing Aβ is also required to be investigated to reveal the etiology of AD clearly. Multiple metalloenzymes (e.g., neprilysin, insulin-degrading enzyme, and ADAM10) have been reported to have an important role in the degradation of Aβ in the brain. These amyloid degrading enzymes (ADE) could interact with redox-active metal ions and affect the pathogenesis of AD. In this review, we introduce and summarize the roles, distributions, and transportations of Cu(I/II) and Fe(II/III), along with previously invented chelators, and the structures and functions of ADE in the brain, as well as their interrelationships.

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