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1.
J. T. Keltjens J. M. H. Hermans G. J. F. A. Rijsdijk C. Van der Drift G. D. Vogels 《Antonie van Leeuwenhoek》1988,54(3):207-220
F430 is the prosthetic group of the methylcoenzyme M reductase of methanogenic bacteria. The compound isolated from Methanosarcina barkeri appears to be identical to the one obtained from the only distinctly related Methanobacterium thermoautotrophicum. F430 is thermolabile and in the presence of acetonitrile or C10
in4
sup-
two epimerization products are obtained upon heating; in the absence of these compounds F430 is oxidized to 12, 13-didehydro-F430. The latter is stereoselectively reduced under H2 atmosphere to F430 by cell-free extracts of M. barkeri or M. thermoautotrophicum. H2 may be replaced by the reduced methanogenic electron carrier coenzyme F420.Abbreviations CH3S-CoM
methylcoenzyme M, 2-methylthioethanesulfonic acid
- HS-CoM
coenzyme M, 2-mercaptoethanesulfonic acid
- F430
Ni(II) tetrahydro-(12, 13)-corphin with a uroporphinoid (III) ligand skeleton
- 13-epi-F430 and 12,13-di-epi-F430
the 12, 13- and 12, 13-derivatives of F430
- 12, 13-didehydro-F430
F430 oxidized at C-12 and C-13
- coenzyme F420
7,8-didemethyl-8-hydroxy-5-deazaflavin derivative
- coenzyme F420H2
reduced coenzyme F420
- MV+
methylviologen semiquinone
- HPLC
high-performance liquid chromatography 相似文献
2.
Abstract: Chronic etorphine treatment of neuroblastoma × glioma NG108-15 cells results in both an increase in adenylate cyclase activity (upon addition of the opiate antagonist naloxone) as well as an homologous desensitization of the opiate receptor. The continued ability of opiate agonists to regulate adenylate cyclase activity following opiate receptor desensitization can be understood by proposing that the catalytic subunit of adenylate cyclase in NG108-15 cells is under tonic regulation by both guanine nucleotide regulatory (Ni ) and stimulatory (Ns ) components. Inactivation of Ni by pertussis toxin (PT) treatment resulted in elevated adenylate cyclase activities comparable to those observed in control cells following chronic opiate treatment. This increased enzymatic activity could not be further induced by PT treatment of cells exposed to opiate previously. In addition, procedures that prevented receptor-mediated activation of Ns , i.e., treatment with NaF or desensitization of the stimulatory receptors (prostaglandin E1 , adenosine) eliminated the increase in adenylate cyclase activity induced by naloxone following chronic opiate exposure. Hence, the increase in enzymatic activity observed following chronic opiate treatment may be due to a loss in tonic inhibitory regulation of adenylate cyclase mediated through Ni resulting in the unimpeded expression of Ns activity. This tonic inhibition of adenylate cyclase activity is one of the multiple mechanisms by which Ni regulates adenylate cyclase in this cell line. 相似文献
3.
4.
Because vitamin B12 and Ni are known to interact and because of the similar metabolic roles of vitamin B12 and folate, an experiment was performed to determine the effect of dietary folate on Ni deprivation in rats. A 2×2 factorially
arranged experiment used groups of nine weanling Sprague-Dawley rats. Dietary variables were Ni, as NiCl2·6H2O, 0 or 1 μg/g; and folic acid, 0 or 2 mg/kg. The basal diet, based on skim milk, contained less than 20 ng Ni/g. After 54
d, an interaction between dietary Ni and folate affected several variables including erythrocyte folate, plasma amino acids,
and femur trace elements. For example, folate deprivation decreased erythrocyte folate; folate supplementation to the Ni-supplemented
rats caused a larger increase in erythrocyte folate concentration than did folate supplementation to the Ni-deprived rats.
Also, dietary Ni affected several plasma amino acids important in one-carbon metabolism (e.g., Ni deprivation increased the
plasma concentrations of glycine and serine). This study shows that dietary Ni, folate, and their interaction can affect variables
associated with one-carbon metabolism. This study does not show a specific site of action of Ni but it indicates that Ni may
be important in processes related to the vitamin B12-dependent pathway in methionine metabolism, possibly one-carbon metabolism.
US Department of Agriculture, Agricultural Research Service, Northern Plans Area is an equal opportunity/affirmative action
employer and all agency services are available without discrimination. 相似文献
5.
Shigeko Ishimatsu Toshihiro Kawamoto Koji Matsuno Yasushi Kodama 《Biological trace element research》1995,49(1):43-52
In this study, eight kinds of nickel (Ni) compounds were orally administered to Wistar male rats and the distribution of each
compound was investigated 24 h after the administration. The Ni compounds used in this experiment were nickel metal [Ni−M],
nickel oxide (green) [NiO(G)], nickel oxide (black) [NiO(B)], nickel subsulfide [Ni3S2], nickel sulfide [NiS], nickel sulfate [NiSO4], nickel chloride [NiCl2], and nickel nitrate [Ni(NO3)2]. The solubilities of the nickel compounds in saline solution were in the following order; [Ni(NO3)2>NiCl2>NiSO4]≫[NiS>Ni3S2]>[NiO(B)>Ni−M>NiO(G)]. The Ni level in the visceral organs was higher in the rats given soluble Ni compounds; Ni(NO3)2, NiCl2, NiSO4, than that in the rats receiving other compounds. In the rats to which soluble Ni compounds were administered, 80–90% of
the recovered Ni amounts in the examined organs was detected in the kidneys. On the other hand, the Ni concentration in organs
administered scarcely soluble Ni compounds; NiO(B), NiO(G), and Ni−M were very low. The estimated absorbed fraction of each
Ni compounds was increased with the increase of the solubility. These results suggest that the kinetic behavior of Ni compounds
administered orally is closely related with the solubility of Ni compounds, and that the solubility of Ni compounds is one
of the important factors for determining the health effect of Ni compounds. 相似文献
6.
James B. Orenberg Kristi M. Kjos Reva Winkler Joseph Link James G. Lawless 《Journal of molecular evolution》1982,18(2):137-143
Summary The interactions of Ni(II) cation with a representative suite of purine bases and the respective nucleosides and nucleotides have been studied by ultraviolet difference spectroscopy. Apparent association constants, Kapp, were determined for each system at pH 7.0, using computer linear regression coupled with an iteration technique. The specificity of binding of Ni2+ for the purine nucleotides studied at pH 7.0 was 5-GMP > 5-IMP > 5-AMP; a similiar ordering was also found for the respective nucleosides and bases. In this study binding was not observed for the suite of pyramidines used, although a Ni2+ - cytidine complex has been observed (Fiskin and Beer, 1965). It was also found that Ni2+ bound more strongly to the purine 5-nucleotides than to the respective nucleosides and bases. These trends are explained in terms of metal-ligand bonds and available bonding positions on the ligands. A role for metal-ion-nucleotide types of complexes is suggested in the processes that might have given rise to the origin of life. 相似文献
7.
Maria P. Abbracchio R. Mark Evans J. Daniel Heck Orazio Cantoni Max Costa 《Biological trace element research》1982,4(4):289-301
The effects of serum components and amino acids on the uptake and cytotoxicity of NiCl2 were examined in cultured Chinese hamster ovary (CHO) cells. CHO cells maintained in a minimal salts/glucose medium accumulated
10-fold more63Ni than did cells maintained in complete medium supplemented with 10% fetal bovine serum. Cell-surface binding of63Ni appeared to account for the majority of this increased accumulation of cell-associated nickel observed in the simple maintenance
medium since such increases were reduced 70% by trypsin treatment. The addition of the Ni2+-binding amino acids cysteine or histidine to the salts/glucose medium markedly decreased63Ni accumulations, an effect not observed following addition of any of several amino acids that do not bind Ni2+. Supplementation of the salts/glucose medium with fetal bovine serum decreased in a concentration dependent fashion both
the63Ni2+ uptake and cell detachment caused by Ni2+, while dialyzed (amino acid-free) serum was 3–5-fold less effective than undialyzed serum at reducing63Ni2+ uptake and similarly exhibited only a slight protective effect against nickel-induced cytotoxicity. Supplementation of dialyzed
serum with cysteine at levels approximating those in whole serum partially restored its inhibitory activity toward nickel
uptake by cells and restored completely its inhibition of nickel's cytotoxicity, indicating the predominant role of specific
amino acids over serum proteins in regulating the uptake and subsequent cytotoxicity of Ni2+. Addition of cysteine to the salts/glucose medium during a 2 h exposure of cells to either 100 μM HgCl2 or 1 mM NiCl2 masked the cytotoxic effects of these metal ions. These results demonstrate the importance of extracellular small molecular
weight metal ion chelators in altering the biological effects of metal ions at the level of metal uptake. 相似文献
8.
Seok Hyun Song Moses Cho Inchul Park Jong‐Gyu Yoo Kyung‐Tae Ko Jihyun Hong Jongsoon Kim Sung‐Kyun Jung Maxim Avdeev Sungdae Ji Seongsu Lee Joona Bang Hyungsub Kim 《Liver Transplantation》2020,10(23)
Layered lithium–nickel–cobalt–manganese oxide (NCM) materials have emerged as promising alternative cathode materials owing to their high energy density and electrochemical stability. Although high reversible capacity has been achieved for Ni‐rich NCM materials when charged beyond 4.2 V versus Li+/Li, full lithium utilization is hindered by the pronounced structural degradation and electrolyte decomposition. Herein, the unexpected realization of sustained working voltage as well as improved electrochemical performance upon electrochemical cycling at a high operating voltage of 4.9 V in the Ni‐rich NCM LiNi0.895Co0.085Mn0.02O2 is presented. The improved electrochemical performance at a high working voltage at 4.9 V is attributed to the removal of the resistive Ni2+O rock‐salt surface layer, which stabilizes the voltage profile and improves retention of the energy density during electrochemical cycling. The manifestation of the layered Ni2+O rock‐salt phase along with the structural evolution related to the metal dissolution are probed using in situ X‐ray diffraction, neutron diffraction, transmission electron microscopy, and X‐ray absorption spectroscopy. The findings help unravel the structural complexities associated with high working voltages and offer insight for the design of advanced battery materials, enabling the realization of fully reversible lithium extraction in Ni‐rich NCM materials. 相似文献
9.
10.
Qun Fan Pengfei Hou Changhyeok Choi Tai‐Sing Wu Song Hong Fang Li Yun‐Liang Soo Peng Kang Yousung Jung Zhenyu Sun 《Liver Transplantation》2020,10(5)
Electrochemical reduction of carbon dioxide (CO2) to fuels and value‐added industrial chemicals is a promising strategy for keeping a healthy balance between energy supply and net carbon emissions. Here, the facile transformation of residual Ni particle catalysts in carbon nanotubes into thermally stable single Ni atoms with a possible NiN3 moiety is reported, surrounded with a porous N‐doped carbon sheath through a one‐step nanoconfined pyrolysis strategy. These structural changes are confirmed by X‐ray absorption fine structure analysis and density functional theory (DFT) calculations. The dispersed Ni single atoms facilitate highly efficient electrocatalytic CO2 reduction at low overpotentials to yield CO, providing a CO faradaic efficiency exceeding 90%, turnover frequency approaching 12 000 h?1, and metal mass activity reaching about 10 600 mA mg?1, outperforming current state‐of‐the‐art single atom catalysts for CO2 reduction to CO. DFT calculations suggest that the Ni@N3 (pyrrolic) site favors *COOH formation with lower free energy than Ni@N4, in addition to exothermic CO desorption, hence enhancing electrocatalytic CO2 conversion. This finding provides a simple, scalable, and promising route for the preparation of low‐cost, abundant, and highly active single atom catalysts, benefiting future practical CO2 electrolysis. 相似文献