PubMed · 14841037
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A C NEISWANDER. 1951. A trace element-cobalt.. https://pubmed.ncbi.nlm.nih.gov/14841037/
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Cobalt influences the methanol metabolism of Desulfofundulus kuznetsovii TPOSR, specifically by modulating the activity of one of its alcohol dehydrogenases (ADH), Adh1. However, the effects of cobalt on the broader proteome of strain TPOSR, as well as the utilization of alcohols besides methanol, remain unexplored. Here, proteomic analyses of strain TPOSR grown with and without cobalt on different alcohol substrates show that cobalt starvation impacts multiple cellular processes, including cobalamin biosynthesis, iron-sulphur cluster assembly and, most prominently, energy metabolism as indicated by altered abundances of hydrogenases and NAD(P)-dependent oxidoreductases. Despite the presence of six ADH-encoding genes in the genome, Adh1 is the dominant ADH during growth not only on methanol but also on several primary alcohols and diols (ethanol, 1-propanol, 1,2-propanediol, 1,3-propanediol, butanol, pentanol and heptanol). Enzymatic assays with purified Adh1 confirm activity with these substrates, except 1,3-propanediol, and show no activity toward secondary alcohols (2-propanol and 2-butanol). Comparative proteomics analyses of other sulphate-reducing microorganisms (SRMs), namely Desulfofundulus australicum and Solidesulfovibrio carbinolicus, further indicate that methanol and ethanol oxidation in SRMs is mediated by a single ADH/AOR pair. Together, these findings highlight the central role of cobalt in alcohol metabolism in strain TPOSR and identify conserved ADH/AOR enzymes as promising candidates for biotechnological applications.
An environmentally benign method to separate iron and cobalt has been developed using a safe chemical, polyvinylpyrrolidone (PVP). The method involves dialysis of PVP-Fe and PVP-Co complexes against triple-distilled water. (59)Fe and (60)Co were used as radioactive tracers of iron and cobalt throughout the experiment. No other chemicals are required for clean separation of cobalt from iron. The optimum condition for separation has been obtained at pH 5 using 10% aqueous solution of PVP. The method is applicable from trace scale to macro-scale. Very high separation factors have been obtained.
Bis(salicylaldehyde)orthophenylenediamine (BSOPD) has been proposed as new analytical reagent for the direct non-extractive spectrophotometric determination of cobalt. It reacts with cobalt in slightly acidic (0.0002-0.001 M H(2)SO(4)) 50% 1,4-dioxanic medium to form a red-orange chelate with a molar ratio 1:1. The reaction is instantaneous and the maximum absorbance was obtained at 458 nm and remains constant for over 24h. The average molar absorption coefficient and Sandell's sensitivity were found to be 1.109 x 10(4)l mol(-1)cm(-1) and 20 ng cm(-2) of Co(II), respectively. Linear calibration graph was obtained for 0.1-15 mg l(-1) of Co(II) with a correlation coefficient value of 0.995 for Co-BSOPD complex. Large excess of 44 cations, anions and complexing agents do not interfere in the determination. The method was successfully used in the determination of cobalt(II) from synthetic mixture and certified reference materials for the purpose of validating the method and the results of analyses were found to be excellent agreement with those of actual values. This developed method was also used for determination of cobalt in some environmental waters (potable and polluted), biological (blood and urine) and soil samples and solution containing both cobalt(II) and cobalt(III). The results of the proposed method for biological samples were comparable with AAS and were found to be in good agreement. The method has high precision and accuracy (s=+/-0.01 for 0.5 mg l(-1)).