scholarly journals Reduction by a Model of NAD(P)H. 27. Role of Bivalent Metal Ion in the Reduction of 2-Acylpyridines and 1-Acylisoquinolines

1980 ◽  
Vol 53 (9) ◽  
pp. 2651-2654 ◽  
Author(s):  
Atsuyoshi Ohno ◽  
Shinro Yasui ◽  
Shinzaburo Oka
Keyword(s):  
Metal Ion ◽  
Bivalent Metal

scholarly journals Synthesis of paucimannose N-glycans by Caenorhabditis elegans requires prior actions of UDP-N-acetyl-d-glucosamine:alpha-3-d-mannoside beta1,2-N-acetylglucosaminyltransferase I, alpha3,6-mannosidase II and a specific membrane-bound beta-N-acetylglucosaminidase

2003 ◽  
Vol 372 (1) ◽  
pp. 53-64 ◽  
Author(s):  
Wenli ZHANG ◽  
Pinjiang CAO ◽  
Shihao CHEN ◽  
Andrew M. SPENCE ◽  
Shaoxian ZHU ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Metal Ion ◽  
Suitable Model ◽  
Bivalent Metal ◽  
C Elegans ◽  
Membrane Bound ◽  
Specific Membrane ◽  
Optimal Ph ◽  
Nematode Development

We have previously reported three Caenorhabditis elegans genes (gly-12, gly-13 and gly-14) encoding UDP-N-acetyl-d-glucosamine:α-3-d-mannoside β1,2-N-acetylglucosaminyltransferase I (GnT I), an enzyme essential for hybrid and complex N-glycan synthesis. GLY-13 was shown to be the major GnT I in worms and to be the only GnT I cloned to date which can act on [Manα1,6(Manα1,3)Manα1,6](Manα1,3)Manβ1, 4GlcNAcβ1,4GlcNAc-R, but not on Manα1,6(Manα1,3)Manβ1-O-R substrates. We now report the kinetic constants, bivalent-metal-ion requirements, and optimal pH, temperature and Mn2+ concentration for this unusual enzyme. C. elegans glycoproteins are rich in oligomannose (Man6–9GlcNAc2) and ‘paucimannose’ Man3–5GlcNAc2(±Fuc) N-glycans, but contain only small amounts of complex and hybrid N-glycans. We show that the synthesis of paucimannose Man3GlcNAc2 requires the prior actions of GnT I, α3,6-mannosidase II and a membrane-bound β-N-acetylglucosaminidase similar to an enzyme previously reported in insects. The β-N-acetylglucosaminidase removes terminal N-acetyl-d-glucosamine from the GlcNAcβ1, 2Manα1,3Manβ- arm of Manα1,6(GlcNAcβ1,2Manα1,3) Manβ1,4GlcNAcβ1,4GlcNAc-R to produce paucimannose Man3GlcNAc2 N-glycan. N-acetyl-d-glucosamine removal was inhibited by two N-acetylglucosaminidase inhibitors. Terminal GlcNAc was not released from [Manα1,6(Manα1,3)Manα1,6] (GlcNAcβ1,2Manα1,3)Manβ1,4GlcNAcβ1,4GlcNAc-R nor from the GlcNAcβ1,2Manα1,6Manβ- arm. These findings indicate that GLY-13 plays an important role in the synthesis of N-glycans by C. elegans and that therefore the worm should prove to be a suitable model for the study of the role of GnT I in nematode development.

scholarly journals Role of hepcidin in oxidative stress and cell death of cultured mouse renal collecting duct cells: protection against iron and sensitization to cadmium

2021 ◽  
Author(s):  
Stephanie Probst ◽  
Johannes Fels ◽  
Bettina Scharner ◽  
Natascha A. Wolff ◽  
Eleni Roussa ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Death ◽  
Cell Fate ◽  
Catalase Activity ◽  
Metal Ion ◽  
Iron Homeostasis ◽  
Collecting Duct ◽  
Duct Cell ◽  
Plasmid Transfection

AbstractThe liver hormone hepcidin regulates systemic iron homeostasis. Hepcidin is also expressed by the kidney, but exclusively in distal nephron segments. Several studies suggest hepcidin protects against kidney damage involving Fe2+ overload. The nephrotoxic non-essential metal ion Cd2+ can displace Fe2+ from cellular biomolecules, causing oxidative stress and cell death. The role of hepcidin in Fe2+ and Cd2+ toxicity was assessed in mouse renal cortical [mCCD(cl.1)] and inner medullary [mIMCD3] collecting duct cell lines. Cells were exposed to equipotent Cd2+ (0.5–5 μmol/l) and/or Fe2+ (50–100 μmol/l) for 4–24 h. Hepcidin (Hamp1) was transiently silenced by RNAi or overexpressed by plasmid transfection. Hepcidin or catalase expression were evaluated by RT-PCR, qPCR, immunoblotting or immunofluorescence microscopy, and cell fate by MTT, apoptosis and necrosis assays. Reactive oxygen species (ROS) were detected using CellROX™ Green and catalase activity by fluorometry. Hepcidin upregulation protected against Fe2+-induced mIMCD3 cell death by increasing catalase activity and reducing ROS, but exacerbated Cd2+-induced catalase dysfunction, increasing ROS and cell death. Opposite effects were observed with Hamp1 siRNA. Similar to Hamp1 silencing, increased intracellular Fe2+ prevented Cd2+ damage, ROS formation and catalase disruption whereas chelation of intracellular Fe2+ with desferrioxamine augmented Cd2+ damage, corresponding to hepcidin upregulation. Comparable effects were observed in mCCD(cl.1) cells, indicating equivalent functions of renal hepcidin in different collecting duct segments. In conclusion, hepcidin likely binds Fe2+, but not Cd2+. Because Fe2+ and Cd2+ compete for functional binding sites in proteins, hepcidin affects their free metal ion pools and differentially impacts downstream processes and cell fate.

scholarly journals Catalytic and structural role of the metal ion in dUTP pyrophosphatase

2003 ◽  
Vol 100 (10) ◽  
pp. 5670-5675 ◽  
Author(s):  
D. Mustafi ◽  
A. Bekesi ◽  
B. G. Vertessy ◽  
M. W. Makinen
Keyword(s):  
Metal Ion ◽  
Structural Role

Thermally Induced Electron Transfer in a CsCoFe Prussian Blue Derivative: The Specific Role of the Alkali-Metal Ion

2004 ◽  
Vol 116 (28) ◽  
pp. 3814-3817 ◽  
Author(s):  
Anne Bleuzen ◽  
Virginie Escax ◽  
Alban Ferrier ◽  
Françoise Villain ◽  
Michel Verdaguer ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Alkali Metal ◽  
Prussian Blue ◽  
Metal Ion ◽  
Specific Role ◽  
Alkali Metal Ion ◽  
Thermally Induced

Why do zeolites induce an unprecedented electronic state on exchanged metal ions?

2017 ◽  
Vol 19 (36) ◽  
pp. 25105-25114 ◽  
Author(s):  
Akira Oda ◽  
Takahiro Ohkubo ◽  
Takashi Yumura ◽  
Hisayoshi Kobayashi ◽  
Yasushige Kuroda
Keyword(s):  
Metal Ions ◽  
Electronic State ◽  
Base Metal ◽  
Metal Ion ◽  
High Efficiency ◽  
Lewis Base ◽  
Mfi Zeolite ◽  
Adsorption Processes ◽  
Exact Position

Understanding the exact position and the detailed role of the Al array in zeolites is essential for elucidating the origin of unique properties and for designing zeolite materials with high efficiency in catalytic and adsorption processes. In this work, we advanced pivotal roles of Lewis base–metal ion bifunctionality caused by Al atoms arrayed circumferentially in the MFI-zeolite pores.

One-dimensional cadmium(II)/bicinate(−1) complexes : The role of the alkali metal ion used in the reaction medium

Polyhedron ◽  
2011 ◽  
Vol 30 (2) ◽  
pp. 397-404 ◽  
Author(s):  
Eugenia Katsoulakou ◽  
Konstantis F. Konidaris ◽  
Aris Terzis ◽  
Catherine P. Raptopoulou ◽  
Spyros P. Perlepes ◽  
...  
Keyword(s):  
Alkali Metal ◽  
Metal Ion ◽  
Reaction Medium ◽  
Alkali Metal Ion ◽  
One Dimensional
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