PubMed · 8753571
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S Nomoto. 1995. [Cobalt].. https://pubmed.ncbi.nlm.nih.gov/8753571/
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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.
The complex of Co(phen)2dppz3+ (where phen is ophenanthroline, and dppz is dipyrido [3, 2-a: 2', 3'-c] phenazine) has been synthesized. This complex was characterized by elemental analysis, molar conductivity, IR and 1H NMR spectroscopy. The interaction of the complex with calf thymus DNA has been studied using absorption and emission spectroscopy, DNA melting techniques, cyclic voltammetric, viscosity, and electrophoresis measurements. The compound shows absorption hypochromicity, fluorescence enhancement, DNA melting temperature, and the specific viscosity increased when binding to calf thymus DNA. CV measurement shows that the shifts in oxidation-reduction potential and change in peak current with addition of DNA. The complex is also shown to be more efficient photosensitisers for single strand breaks in plasmid DNA.
BACKGROUND: Duplex DNA is more than a simple information carrier. The sequence-dependent structure and its inherent deformability, in concert with the subtle modulating effects of the environment, play a crucial role in the regulation and packaging of DNA. Recent advances in force field and simulation methodologies allow molecular dynamics simulations to now represent the specific effects of the environment. An understanding of the environmental dependence of DNA structure gives insight into how histones are able to package DNA, how various proteins are able to bind and modulate nucleic acid structure and will ultimately aid the design of molecules to package DNA for more effective gene therapy. RESULTS: Molecular dynamics simulations of d[ACCCGCGGGT]2 in solution in the presence of hexaamminecobalt(III) [Co(NH3)6(3+)] show stabilization of A-DNA and spontaneous B-DNA to A-DNA transitions, which is consistent with experimental results from NMR and Raman spectroscopic and X-ray crystallographic studies. In the absence of Co(NH3)6(3+), A-DNA to B-DNA transitions are observed instead. In addition to their interaction with the guanines in the major groove, Co(NH3)6(3+) ions bridge opposing strands in the bend across the major groove, probably stabilizing A-DNA. CONCLUSIONS: The simulation methods and force fields have advanced to a sufficient level that some representation of the environment can be seen in nanosecond length molecular dynamics simulations. These simulations suggest that, in addition to the general explanation of A-DNA stabilization by dehydration, hydration and ion association in the major groove stabilize A-DNA.