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  • 1
    Electronic Resource
    Electronic Resource
    Selenium requirement for active xanthine dehydrogenase from Clostridium acidiurici and Clostridium cylindrosporum (1979)
    Springer
    Archives of microbiology 121 (1979), S. 255-260 
    Details
    ISSN: 1432-072X
    Keywords: Purine fermentation ; Xanthine dehydrogenase ; Selenium ; Tungsten ; Molybdenum ; Clostridium acidiurici ; Clostridium cylindrosporum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The xanthine dehydrogenase of Clostridium acidiurici and C. cylindrosporum was assayed with methyl viologen as acceptor. In C. acidiurici the basal activity level was about 0.3 μmol/min x mg of protein. Cells grown on uric acid in the presence of 10-7 M selenite showed a 14-fold increase in xanthine dehydrogenase activity, which decreased with higher selenite concentrations (10-5 M). The supplementation with 10-7 M molybdate or tungstate was without effect. High concentrations of tungstate decreased the xanthine dehydrogenase if selenite was also present. In comparison, high concentrations of molybdate affected only a small decrease in activity level at the optimal concentration for selenite and relieved to some degree the inhibitory effect of 10-5 M selenite. With hypoxanthine and xanthine as substrates for growth again only the addition of selenite was necessary to show a similar increase in xanthine dehydrogenase activity. C. acidiurici could be grown in a mineral medium. Both xanthine dehydrogenase and formate dehydrogenase exhibited the highest level of activity if selenite and tungstate were present in that medium. In C. cylindrosporum the basal activity level of xanthine dehydrogenase was about 0.95 μmol/min x mg of protein. The addition of 10-7 M selenite to the growth medium increased the activity level about 3-fold, but the highest level (3.7 U/mg) was reached if 10-7 M molybdate was also added. The presence of tungstate resulted in a decreased enzyme activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425064
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  • 2
    Electronic Resource
    Electronic Resource
    Comparative studies on physiology and taxonomy of obligately purinolytic clostridia (1984)
    Springer
    Archives of microbiology 138 (1984), S. 345-353 
    Details
    ISSN: 1432-072X
    Keywords: Clostridium acidiurici ; Clostridium cylindrosporum ; Clostridium purinolyticum ; Purine metabolism ; Selenite ; Antibiogram ; DNA homology ; Taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Eleven strains of obligately purinolytic clostridia have been studied with respect to their assignment to the three type strains of Clostridium acidiurici, C. cylindrosporum, and C. purinolyticum. DNA/DNA-hybridization proved to be the method of choice for differentiation whereas phenotypic characteristics such as spore morphology, substrate spectra, nutritional requirements, product formation, and sensitivity against various antibiotics did not allow unequivocal identification. All strains depended on selenite for growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00410902
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  • 3
    Electronic Resource
    Electronic Resource
    Accumulation and incorporation of 185W-tungsten into proteins of Clostridium acidiurici and Clostridium cylindrosporum (1987)
    Springer
    Archives of microbiology 147 (1987), S. 295-299 
    Details
    ISSN: 1432-072X
    Keywords: Clostridium acidiurici ; Clostridium cylindrosporum ; Tungsten uptake ; Molybdate antagonism ; Formate dehydrogenase ; Tungsten-binding-storage protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Uptake of tungstate by growing cells was unaffected by the presence of molybdate in Clostridium cylindrosporum, whereas in C. acidiurici the accumulation was decreased by molybdate at 10-6 mol/l tungstate and higher concentrations. The labelling pattern of soluble proteins by 185W-tungsten indicated after gel chromatography the presence of three different tungstoproteins in both bacteria. Formate dehydrogenase activity always eluted at a maximum of tungsten labelling. The incorporation of tungsten into formate dehydrogenase containing fractions and a possible tungsten-binding-storage protein was independent of the presence of excess molydate pointing to a genuine role for tungstate in these bacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00463491
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  • 4
    Electronic Resource
    Electronic Resource
    The pyridine-nucleotide cycle in tobacco (1986)
    Springer
    Planta 167 (1986), S. 226-232 
    Details
    ISSN: 1432-2048
    Keywords: NAD pyrophosphatase ; Nicotinamidase ; Nicotiana (pyridine-nucleotide cycle) ; Nicotine biosynthesis ; Pyridine nucleotide cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In order to elucidate the NAD-recycling pathway the following enzyme activities have been characterized in different tobacco tissues and in tomato root: NAD pyrophosphatase, nicotinamide mononucleotide (NMN)/nicotinic acid mononucleotide (NaMN) glycohydrolases, nicotinamidase and nicotinic acid phosphoribosyltransferase. The investigations were performed with protein extracts purified by gel filtration and enzymatic activities were determined by high-performance liquid chromatography methods. The kinetic parameters of the different enzymes from tobacco root and their specificity are reported. The data are in favor of the so-called pyridine-nucleotide cycle VI (NAD→NMN→nicotinamide→nicotinic acid→NaMN→nicotinic acid adenine dinucleotide→NAD). In the nicotine-producing tobacco root a further direct route leading from NaMN to nicotinic acid is proposed. These data are reconciled with the assumption that it is nicotinic acid which is provided by the pyridine-nucleotide cycle for the synthesis of nicotine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00391419
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  • 5
    Electronic Resource
    Electronic Resource
    Regulation in tobacco callus of enzyme activities of the nicotine pathway (1986)
    Springer
    Planta 168 (1986), S. 402-407 
    Details
    ISSN: 1432-2048
    Keywords: Methylputrescine oxidase ; Nicotiana ; Nicotine biosynthesis ; Ornithine decarboxylase ; Putrescine methyltransferase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nicotine synthesis was stimulated by reduction of the medium auxin concentration (induction medium) in callus tissue originating from Nicotiana tabacum cv. Samsun. The enzyme activities of the route ornithine to methylpyrroline, which are those of ornithine decarboxylase, putrescine methyltransferase and methylputrescine oxidase, were determined during callus growth in the induction medium and as a control under non-nicotine-stimulating conditions (growth medium). The enzymes were assayed by high-performance liquid chromatography. Whereas the activities of ornithine decarboxylase were very similar under nicotine-stimulating and non-stimulating conditions, those of putrescine methyltransferase and methyl-putrescine oxidase increased strongly in the induction medium. In addition, the pools of putrescine and methylputrescine were determined throughout the callus growth cycle. Both sets of data strongly confirm the supposition that putrescine methyl-transferase is the enzyme under stringent control for nicotine biosynthesis, whereas the subsequent methylputrescine oxidase is co-regulated, although less stringently.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392368
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  • 6
    Electronic Resource
    Electronic Resource
    Regulation in tobacco callus of enzyme activities of the nicotine pathway (1986)
    Springer
    Planta 168 (1986), S. 408-413 
    Details
    ISSN: 1432-2048
    Keywords: Callus culture (nicotine pathway) ; Nicotiana (nicotine pathway) ; Nicotine biosynthesis ; Pyridine nucleotide cycle ; Pyridine nucleotide glycohydrolase ; Quinolinic acid phosphoribosyltransferase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In tobacco callus, the induction of nicotine synthesis, which stimulates enzyme activities of the ornithine-methylpyrroline route (see the preceding paper), also leads to marked changes in the enzyme activities of the pyridine-nucleotide cycle. This cycle provides the metabolite (probably nicotinic acid) for condensation with methylpyrroline to produce nicotine. The activities of eight enzymes of the pyridine-nucleotide cycle and of quinolinic-acid phosphoribosyltransferase, the anaplerotic enzyme, were determined by high-performance liquid chromatography assays. The distinct changes of their activities upon induction of nicotine synthesis lead to the following conclusions: i) nicotinic acid is the relevant metabolite which is provided by the pyridine-nucleotide cycle and consumed for nicotine synthesis. ii) The enhancement of the nicotinic-acid pool arises in two ways, by synthesis of NAD and degradation via nicotinamide mononucleotide and by a direct route from nicotinic-acid mononucleotide (NaMN) which is degraded by a glycohydrolase with a rather high K m value. Such a K m value prevents the complete depletion of the NaMN pool.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392369
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