Cobalt biological significance

The existence of copper-nitrosyl complexes of biological significance has been briefly discussed here (Section VII). It is worth pointing out that nitrosyl complexes of other metal-containing proteins may form, and that these may be important in understanding the effects of NO on living cells. Nitrosyl complexes of many other metals are well documented (e.g., Werner and Karrer, 1918 Moeller, 1952) and include complexes of nickel, cobalt, and ruthenium. Some such complexes may be less obvious than the paramagnetic and often colorful... 

ICP-MS was used for the detection of biologically significant metalloporphyrins separated by RP-HPLC by Kumar et al. [43]. Cobalt protoporphyrin (CoPP), iron protoporphyrin (hemin) and zinc protoporphyrin (ZnPP) were separated using a Cl column (due to the relatively large molecular mass of the compounds) and a mobile phase optimised with 68% methanol at pH 4.5 (Fig. 2). Detection limits were... 

Porphyrins with metals other than iron (and cobalt) are not of particular direct relevance to the present section, although it should be noted that porphyrins have been extracted from coal and oil shales with metals such as gallium and the early transition metals coordinated. The biological significance of these observations is questionable. Nevertheless, detailed studies on a range of metalloporphyrins have contributed substantially to our appreciation of the bonding in such molecules, and the influence of cis and trans ligands on their structure and reactivity.599 609... 

Inorganic cobalt is transported in the blood by albumin and transferrin it is taken up by the liver. The serum concentration amounts to 1.9-7.6 mmol/1. An increased value is a sign of liver cell necrosis (e. g. acute hepatitis). Its biological significance is attributed to its position as a central atom in vitamin B12 and its involvement in the release of renin and erythropoietin. 

A. Biological Significance of Iron, Zinc, Copper, Molybdenum, Cobalt, Chromium, Vanadium, and Nickel... 

The synthesis of (7-alkylcobalts from the reaction of Co hydrides and alkenes is relevant to the use of Co hydrides in alkene hydroformylation and is of interest because of the biological significance of carbon-cobalt bonds in vitamin B12 chemistry. The reaction of HCo(CO)4 with simple alkenes involves hydrometalation as a key step in hydrogenation, isomerization or hydroformylation of alkenes . ff-Alkylcobalt compounds are detectable intermediates in reactions of HCo(CO)4 and alkenes by Ir, but... 

It is also clear that copper is of little significance in most of these organisms relative to its multitude of roles in multicellular eukaryotes, while in these eukaryotes the role of nickel and cobalt is further diminished. We may conjecture that biological systems did not use copper extensively before the advent of an oxidizing atmosphere based on dioxygen (Frausto da Silva and Williams, 1991). 

Figure 28 Schematic presentation of the relative situation of the different types of radiations used in therapy. Two criteria are considered the physical selectivity and the LET (or radiobiological properties). For the low-LET radiations, the physical selectivity was improved from the historical 200-kV x-rays to cobalt-60 gamma rays and the modern linacs. Even with the linacs today, significant improvement is continuously achieved (IMRT, etc.). Among the low-LET radiation, the proton beams have the best physical characteristics, but one of the issues is the proportion of patients who will benefit from proton irradiation. A similar scale can be drawn for high-LET radiation the heavy-ion beams have a physical selectivity similar to protons. Selection between low- and high-LET radiation is a biological/medical problem it depends on the tumor characteristics, and reliable criteria still need to be established (see text). (From Ref 54.)...

Pellet F, Perdrix A, Vincent M and Mallion JM (1984) Biological determination of urinary cobalt. Significance in occupational medicine in the monitoring of exposures to sintered metallic carbides. Arch Mai Prof Med Trav Secur Soc 45 81-85. Perdrix A, Pellet F, Vincent M, De Gaudemaris R and Mallion JM (1983) Cobalt and sintered metal carbides. Value of the determination of cobalt as a tracer for exposure to hard metals. Toxicol Fur Res 5 233-240. 

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