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101.
Purification and characterization of an activator protein for methanol dehydrogenase from thermotolerant Bacillus spp 总被引:2,自引:0,他引:2
N Arfman J Van Beeumen G E De Vries W Harder L Dijkhuizen 《The Journal of biological chemistry》1991,266(6):3955-3960
All thermotolerant methanol-utilizing Bacillus spp. investigated by us possess a NAD-dependent methanol dehydrogenase (MDH) activity which is stimulated by a protein present in the soluble fraction of Bacillus sp. C1 cells. This activator protein was purified to homogeneity from Bacillus sp. C1 cells grown at a low dilution rate in a methanol-limited chemostat culture. The native activator protein (Mr = 50,000) is a dimer of Mr = 27,000 subunits. The N-terminal amino acid sequence revealed no significant similarity with any published sequences. Stimulation of MDH activity by the activator protein required the presence of Mg2+ ions. Plots of specific MDH activity versus activator protein concentration revealed Michaelis-Menten type kinetics. In the presence of activator protein, MDH displayed biphasic kinetics (v versus substrate concentration) toward C1-C4 primary alcohols and NAD. The data suggest that in the presence of activator protein plus Mg2+ ions, MDH possesses a high affinity active site for alcohols and NAD, in addition to an activator- and Mg2(+)-independent low affinity active site. The activation mechanism remains to be elucidated. 相似文献
102.
J. Harder 《Archives of microbiology》1997,168(3):199-204
A bacterium, strain 22Lin, was isolated on cyclohexane-1,2-diol as sole electron donor and carbon source and nitrate as electron
acceptor. Cells are motile rods and are facultatively anaerobic. A phylogenetic comparison based on the total 16S rRNA gene
sequence allowed the assignment of the isolate to the genus Azoarcus. Cyclohexanol, cyclohexanone, cyclohexane-1,3-diol, and cyclohexane-1,3-dione, which are oxidized by a different denitrifying
strain, did not support denitrifying growth of isolate 22Lin. On the contrary, cyclohexanol (I50 = 37 μM) and cyclohexanone (I50 = 28 μM) inhibited growth on cyclohexane-1,2-diol, but not on acetate. NAD was reduced by crude extracts of strain 22Lin
in the presence of cyclohexane-1,2-dione, but not in the presence of cyclohexanone or cyclohexane-1,3-dione. The formation
of 6-oxohexanoate from cyclohexane-1,2-dione and of adipate during NAD reduction suggests that strain 22Lin possesses a carbon–carbon
hydrolase that transforms cyclohexane-1,2-dione into 6-oxohexanoate. This pathway was once observed in an aerobic pseudomonad
that was lost and could not be reisolated. Here, the application of strictly anoxic enrichment conditions enabled the reisolation
of another strain (22Lin) that uses this pathway.
Received: 3 February 1997 / Accepted: 12 May 1997 相似文献
103.
Yanming Zhang Peter Matthiesen Reiner Siebert Svetlana Harder Michael Theile Siegfried Scherneck B. Schlegelberger 《Human genetics》1998,103(6):727-729
Dual-color fluorescence in situ hybridization was performed to detect the frequency and extent of 6q deletions in ten breast
carcinoma cell lines. In five cell lines, the 6q deletions involved large regions extending from 6q12–q16 to 6q27, and in
one the deletion extended from the region distal to YAC 751G10 at 6q25.1 to 6q27. In two cell lines, 6q deletions occurred
only in cells with polysomy 6, indicating that such deletions might be secondary chromosomal aberrations and reflect late
genetic changes in breast carcinomas. In addition, an overrepresentation of 6q21–q22.2 was detected in one cell line.
Received: 17 July 1998 / Accepted: 28 September 1998 相似文献
104.
105.
Prof. Dr. Richard Harder 《Planta》1953,42(1-2):19-29
Zusammenfassung Den Pflanzen wurde ein Blühimpuls durch verschieden lange Behandlung mit 9stündigem Kurztag (während 2, 8 und 16 Tagen) gegeben und die Entwicklung der Infloreszenzen im anschließenden 12-, 18- und 24stündigen Tag beobachtet. Sie war je nach der Tageslänge sehr verschieden. Die Belichtungsdauer während der Entwicklung der Blüten übt also einen starken Einfluß auf das Blühergebnis aus. Zwischen 18- und 24stündigem Langtag war aber kein statistisch zu sichernder Einfluß feststellbar; beide wirkten gleich stark verzögernd gegenüber 12stündigem Tag, wobei die für das Blühen sehr viel günstigere Wirkung des 12-Std-Tages aber daher kommt, daß er fürKalanchoë Bloßfeldiana noch blühfördernde Kurztagswirkung hat.Mit 6 Textabbildungen.
Wilhelm Ruhland zum 75. Geburtstag. 相似文献
106.
Zusammenfassung Der Kurztag wurde fürKalanchoë Bloßfeldiana auf 2 Stunden bis hinab zu 1 Sek. abgekürzt. Bei Anwendung von natürlichem Tageslicht oder elektrischem Licht von 60–80 000 Lux bei Zimmertemperatur kamen die Pflanzen bei allen diesen Tageslängen zum Blühen.Man kann die Pflanzen also täglich 23 Stunden, 59 Min. und 59 Sek. im Dunkeln halten und braucht sie nur 1 Sek. zu belichten, um die Blütenbildung herbeizuführen.Alle Blütenstände waren völlig normal ausgebildet, unverlaubt und relativ reichblütig.Mit abnehmender Belichtungszeit ging die Blütenzahl zurück, und der Zeitpunkt des ersten Sichtbarwerdens der Infloreszenzen sowie des Aufblühens der Knospen wurde hinausgeschoben. Von 20 Min. abwärts trat diese Abnahme des Blühimpulses aber nicht mehr klar ein, so daß bei den längeren Belichtungszeiten wohl auch die Menge der Assimilate — die bei den sehr kurzen Zeiten überall wohl als gleich unbedeutend angesehen werden darf—mit eine Rolle spielte.Mit 3 Textabbildungen. 相似文献
107.
108.
109.
R Greinert C Thieke E Detzler O Boguhn D Frankenberg D Harder 《Radiation research》1999,152(4):412-420
Premature chromosome condensation (PCC) experiments using human lymphocytes with centromere staining have shown that after exposure to 3.45 MeV alpha-particle radiation, the full number of dicentric chromosomes appears when the cell fusion protocol is applied immediately after irradiation. In this case, the time available for repair and misrepair of DNA damage is only about 30 min. The number of dicentrics does not change with a further increase in the time available for chromatin rearrangement. This fast response confirms the expectation based on our previous experiments using PCC with 150 kV X rays in which the alpha component of the yield of dicentrics was found to appear when the cell fusion protocol was applied immediately after irradiation, whereas the beta component was delayed by several hours. The time constant for rejoining of the excess acentric chromosome fragments is found to be donor-specific and not to differ for alpha particles and X rays, but alpha-particle radiation leaves a larger fraction of the excess acentric fragments unrejoined. The RBEs of the 3.45 MeV alpha-particle radiation compared to 150 kV X rays, evaluated for the alpha component for the yield of dicentrics and for the yield of unrepaired acentric fragments, have almost equal values of about 4. This is consistent with data in the literature on chromosome aberrations observed in metaphase that show the equality of the RBE values for production of dicentrics and acentric fragments. Our experimental results concerning the fast kinetics of the alpha component of the yield of exchange-type chromosome aberrations are not consistent with Lea's pairwise lesion interaction model, and they support the proposed alternative mechanism of lesion-nonlesion interaction between chromatin regions carrying clustered DNA damage and intact chromatin regions. 相似文献
110.