Nickel complexes biology

The low molecular weight L-histidine nickel complex can cross biological membranes (Sarkar 1984). How nickel gets inside of cells may determine the effects of the nickel compounds. If nickel ions are taken into the cytosol and bind to protein, they are not delivered to the nucleus, which prevents the interaction of nickel ions with DNA. Crystalline nickel compounds are phagocytized and nickel ions are delivered to the nucleus where they interact with DNA or DNA protein complexes (Costa 1995). 

Syntheses of 5,12-dioxocyclams containing the quinoxaline nucleus have utilized the ring opening of both rings of 3,3,6-trimethyl-l-azapenam 148. Treatment of 148 with acid gave the cyclam (Equation 16) after reduction of the imine. Unfortunately, this and related cyclams and their nickel complexes showed little useful biological activity in their interaction with DNA <2003JOC4179>. 

Neurospora crassa calcium transport, 571 cation transport, 559 Neurosporin, 676 Neurotransmitters secretion calcium, 595 Neutral complexes electrical properties, 143 Neutron absorbers reprocessing irradiated nuclear fuel criticality, 926 Neutron activation analysis metal complexes biology, 550 Neutron capture fission product, 883 Nickel... 

Studies on the role of nickel in biological processes have received much attention because of the involvement of nickel in the active site of many hydrogenases [93]. The most noteworthy characteristics of the nickel sites in the hydrogenases are the existence of stable tervalent nickel and the low Ni(III/II) redox potential ( -150 to -400 mV vs. NHE) [94]. The redox potential of the Ni(III/TI) couple in the enzyme is much lower than the potentials of commonly observed Ni(III/II) couples in synthetic complexes [95]. Different approaches have been made to increase the stability of Ni(III) and thus lower the redox potential of the Ni(IIFII) redox couple in synthetic complexes [96]. Studies on the stabilization of the Ni(III) state in synthetic complexes could afford information regarding the stabilization of Ni(III) in the enzymes. The nickel redox centers of the enzymes are considered to be the binding site for the catalytic cycle in the biological process [93]. 

The broadly defined porphyrin research area is one of the most exciting, stimulating and rewarding for scientists in the fields of chemistry, physics, biology and medicine. The beautifully constructed porphyrinoid ligand, perfected over the course of evolution, provides the chromophore for a multitude of iron, magnesium, cobalt and nickel complexes which are primary metabolites and without which life itself could not be maintained. 

It was in the early 1970s that Semmelhack and coworkers reported the nickel(0)-catalyzed C-C bond formation as the key step in the total synthesis of a biologically active compound. The aryl ring was activated by the oxidative addition of Arl onto a nickel(O) species. Subsequent reaction of the a-aryl nickel complex with a carbanion generated with a base such as lithium diisopropylamide... 

The coordination chemistry of nickel in oxidation states different from 0 or II has experienced a considerable growth in recent years, due in part to the involvement of nickel in biological processes, where the oxidation states i and iii may play an important role (see next section). Organometallic nickel(i) and nickel(iii) species have been postulated as intermediates in important organometallic reactions, such as oxidative addition and reductive elimination. " More recently, Hillhouse has pointed out the importance of the oxidation of Ni(ii) alkyl-alkoxo and alkyl-amido complexes to achieve G-O and G-N reductive elimination, presumably through the intermediacy of Ni(iii) species. 

Matienko, L.I. Binyukov, V.I. Mosolova, L.A. Mil, E.M. Zaikov, G.E. Supramolecular Nanostructures on the Basis of Catalytic Active Heteroligand Nickel Complexes and their Possible Roles in Chemical and Biological Systems. J. Biol. Res. 2012,1, 37-44. 

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