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  • 1
    Electronic Resource
    Electronic Resource
    Kinetics and biotransformation of benzo(a)pyrene inChironomus riparius (1982)
    Springer
    Archives of environmental contamination and toxicology 11 (1982), S. 25-31 
    Details
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Uptake and depuration kinetics for benzo(a)pyrene (B(a)P) were determined for the midgeChironomus riparius (Diptera) with one and two compartment models. Nonfeeding animals were exposed to nominal 1.0μg·L−1 14CB(a)P for eight hr. Depuration over eight hr was determined in animals with and without substrate. The uptake rate constant was 214+-20 hr−1 (X+-SE, n=3), while elimination rate constants for the first four hr were 0.22 hr−1 (with substrate) and 0.06 hr−1 (without substrate). Biphasic depuration was observed with an initial rapid phase that lasted several hr. Approximately 10% of accumulated14C was associated with exoskeleton. As much as 50% of the accumulated B(a)P was transformed into polar compounds after one hr. Based on steady state14C concentration, an apparent bioconcentration factor of 650 was determined. The bioconcentration value based on B(a)P analysis was 200.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01055182
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  • 2
    Electronic Resource
    Electronic Resource
    Purification and characterization of the NADH:ferredoxinBPH oxidoreductase component of biphenyl 2,3-dioxygenase from Pseudomonas sp. strain LB400 (1998)
    Springer
    Archives of microbiology 170 (1998), S. 106-112 
    Details
    ISSN: 1432-072X
    Keywords: Key words Oxidoreductase ; Flavoprotein ; Dioxygenase ; Biphenyl ; Polychlorinated biphenyl ; Electron transport ; Pseudomonas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract NADH:ferredoxinBPH oxidoreductase (reductaseBPH) of biphenyl 2,3-dioxygenase was purified over 47-fold to homogeneity with a yield of 41% from cell extract of Pseudomonas sp. strain LB400. ReductaseBPH transfers reducing equivalents from NADH to the catalytic oxygenase component (ISPBPH) via a ferredoxin (ferredoxinBPH) during the oxidation of biphenyl to cis-biphenyl 2,3-dihydrodiol. ReductaseBPH was a monomer with a molecular weight of 43,600 as determined by electrophoresis under denaturing conditions. Gel filtration column chromatography gave a molecular weight of 41,500 for native reductaseBPH. The absorbance spectrum of the protein in its oxidized state had maxima at 271 nm, 376 nm and 448 nm with shoulders at 422 nm and 476 nm. The peak around 448 nm was partially bleached upon reduction with NADH under anoxic conditions. ReductaseBPH contained 0.89 mol FAD/mol protein. ReductaseBPH was required for oxidation of biphenyl to cis-biphenyl 2,3-dihydrodiol by ISPBPH and ferredoxinBPH. Potassium ferricyanide, 2,6-dichlorophenolindophenol (DCPIP), nitrobluetetrazolium and cytochrome c served as artificial electron acceptors. Reduction of cytochrome c was dependent upon the presence of ferredoxinBPH. The fastest rate of DCPIP reduction occurred at pH 7.2 and 32° C. The apparent K m for NADH and NADPH in the DCPIP assay were 58 μM and 156 μM, respectively. V max was 3,120 U mg–1 for NADH and 1,140 U mg–1 for NADPH. NADH is most likely the physiological electron donor for oxidation of biphenyl and polychlorinated biphenyls.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050621
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  • 3
    Electronic Resource
    Electronic Resource
    Purification and properties of ferredoxinBPH, a component of biphenyl 2,3-dioxygenase of Pseudomonas sp strain LB400 (1997)
    Springer
    Journal of industrial microbiology and biotechnology 19 (1997), S. 355-359 
    Details
    ISSN: 1476-5535
    Keywords: Keywords: ferredoxin; dioxygenase; biphenyl; polychlorinated biphenyl; electron transport; Rieske iron-sulfur protein; Pseudomonas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The ferredoxin component (ferredoxinBPH) of biphenyl 2,3-dioxygenase was purified to homogeneity from crude cell extract of Pseudomonas sp strain LB400 using ion exchange, hydrophobic interaction and gel filtration column chromatography. The protein was a monomer with a molecular weight of 15000 and contained 2 gram-atoms each of iron and acid-labile sulfur. Ultraviolet-visible absorbance spectroscopy showed peaks at 325 nm and 460 nm with a broad shoulder around 575 nm. The spectrum was partially bleached in the visible region upon reduction by reductaseBPH with NADPH as the source of electrons. Electron paramagnetic resonance spectrometry showed no signals for the oxidized protein. Upon reduction with sodium dithionite, signals with gx = 1.82, gy = 1.92 and gz = 2.02 were detected. These results indicate that the protein contains a Rieske-type (2Fe-2S) iron-sulfur center. FerredoxinBPH was required for the oxidation of biphenyl by the terminal oxygenase component of the enzyme and is probably involved in the transfer of reducing equivalents from reductaseBPH to the terminal oxygenase during catalysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/sj.jim.2900429
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